diff --git a/app/assets/javascripts/workers/aether_worker.js b/app/assets/javascripts/workers/aether_worker.js
index a75469a29..a1d8e3038 100644
--- a/app/assets/javascripts/workers/aether_worker.js
+++ b/app/assets/javascripts/workers/aether_worker.js
@@ -2,7 +2,7 @@ var window = self;
 var Global = self;
 
 importScripts("/javascripts/lodash.js", "/javascripts/aether.js");
-console.log("Aether Tome worker has finished importing scripts.");
+//console.log("Aether Tome worker has finished importing scripts.");
 var aethers = {};
 
 var createAether = function (spellKey, options) 
diff --git a/app/assets/javascripts/workers/worker_world.js b/app/assets/javascripts/workers/worker_world.js
index dd1142eff..c7a6ee560 100644
--- a/app/assets/javascripts/workers/worker_world.js
+++ b/app/assets/javascripts/workers/worker_world.js
@@ -300,7 +300,7 @@ self.setupDebugWorldToRunUntilFrame = function (args) {
         }
         Math.random = self.debugWorld.rand.randf;  // so user code is predictable
         Aether.replaceBuiltin("Math", Math);
-        replacedLoDash = _.runInContext(self);
+        var replacedLoDash = _.runInContext(self);
         for(var key in replacedLoDash)
           _[key] = replacedLoDash[key];
     }
@@ -346,6 +346,7 @@ self.runWorld = function runWorld(args) {
       self.world.loadFromLevel(args.level, true);
     self.world.preloading = args.preload;
     self.world.headless = args.headless;
+    self.world.realTime = args.realTime;
     self.goalManager = new GoalManager(self.world);
     self.goalManager.setGoals(args.goals);
     self.goalManager.setCode(args.userCodeMap);
@@ -358,17 +359,27 @@ self.runWorld = function runWorld(args) {
   }
   Math.random = self.world.rand.randf;  // so user code is predictable
   Aether.replaceBuiltin("Math", Math);
-  replacedLoDash = _.runInContext(self);
+  var replacedLoDash = _.runInContext(self);
   for(var key in replacedLoDash)
     _[key] = replacedLoDash[key];
   self.postMessage({type: 'start-load-frames'});
   self.world.loadFrames(self.onWorldLoaded, self.onWorldError, self.onWorldLoadProgress);
 };
 
+self.serializeFramesSoFar = function serializeFramesSoFar() {
+  if(!self.world) return;  // We probably got this message late, after delivering the world.
+  if(self.world.framesSerializedSoFar == self.world.frames.length) return;
+  self.onWorldLoaded();
+  self.world.framesSerializedSoFar = self.world.frames.length;
+};
+
 self.onWorldLoaded = function onWorldLoaded() {
-  self.goalManager.worldGenerationEnded();
+  if(self.world.framesSerializedSoFar == self.world.frames.length) return;
+  if(self.world.ended)
+    self.goalManager.worldGenerationEnded();
   var goalStates = self.goalManager.getGoalStates();
-  self.postMessage({type: 'end-load-frames', goalStates: goalStates});
+  if(self.world.ended)
+    self.postMessage({type: 'end-load-frames', goalStates: goalStates});
   var t1 = new Date();
   var diff = t1 - self.t0;
   if (self.world.headless)
@@ -381,10 +392,12 @@ self.onWorldLoaded = function onWorldLoaded() {
   catch(error) {
     console.log("World serialization error:", error.toString() + "\n" + error.stack || error.stackTrace);
   }
+
   var t2 = new Date();
   //console.log("About to transfer", serialized.serializedWorld.trackedPropertiesPerThangValues, serialized.transferableObjects);
+  var messageType = self.world.ended ? 'new-world' : 'some-frames-serialized';
   try {
-    var message = {type: 'new-world', serialized: serialized.serializedWorld, goalStates: goalStates};
+    var message = {type: messageType, serialized: serialized.serializedWorld, goalStates: goalStates, startFrame: serialized.startFrame, endFrame: serialized.endFrame};
     if(transferableSupported)
       self.postMessage(message, serialized.transferableObjects);
     else
@@ -393,11 +406,14 @@ self.onWorldLoaded = function onWorldLoaded() {
   catch(error) {
     console.log("World delivery error:", error.toString() + "\n" + error.stack || error.stackTrace);
   }
-  var t3 = new Date();
-  console.log("And it was so: (" + (diff / self.world.totalFrames).toFixed(3) + "ms per frame,", self.world.totalFrames, "frames)\nSimulation   :", diff + "ms \nSerialization:", (t2 - t1) + "ms\nDelivery     :", (t3 - t2) + "ms");
-  self.world.goalManager.destroy();
-  self.world.destroy();
-  self.world = null;
+
+  if(self.world.ended) {
+    var t3 = new Date();
+    console.log("And it was so: (" + (diff / self.world.totalFrames).toFixed(3) + "ms per frame,", self.world.totalFrames, "frames)\nSimulation   :", diff + "ms \nSerialization:", (t2 - t1) + "ms\nDelivery     :", (t3 - t2) + "ms");
+    self.world.goalManager.destroy();
+    self.world.destroy();
+    self.world = null;
+  }
 };
 
 self.onWorldError = function onWorldError(error) {
@@ -443,6 +459,11 @@ self.finalizePreload = function finalizePreload() {
   self.world.finalizePreload(self.onWorldLoaded);
 };
 
+self.addFlagEvent = function addFlagEvent(flagEvent) {
+  if(!self.world) return;
+  self.world.addFlagEvent(flagEvent);
+};
+
 self.addEventListener('message', function(event) {
   self[event.data.func](event.data.args);
 });
diff --git a/app/lib/Angel.coffee b/app/lib/Angel.coffee
index 3b5f59a75..59547ca16 100644
--- a/app/lib/Angel.coffee
+++ b/app/lib/Angel.coffee
@@ -12,6 +12,9 @@ module.exports = class Angel extends CocoClass
   infiniteLoopTimeoutDuration: 7500  # wait this long for a response when checking
   abortTimeoutDuration: 500  # give in-process or dying workers this long to give up
 
+  subscriptions:
+    'level:flag-updated': 'onFlagEvent'
+
   constructor: (@shared) ->
     super()
     @say 'Got my wings.'
@@ -64,14 +67,6 @@ module.exports = class Angel extends CocoClass
         clearTimeout @condemnTimeout
         @beholdGoalStates event.data.goalStates  # Work ends here if we're headless.
 
-      # We pay attention to certain progress indicators as the world loads.
-      when 'world-load-progress-changed'
-        Backbone.Mediator.publish 'god:world-load-progress-changed', event.data
-      when 'console-log'
-        @log event.data.args...
-      when 'user-code-problem'
-        Backbone.Mediator.publish 'god:user-code-problem', problem: event.data.problem
-
       # We have to abort like an infinite loop if we see one of these; they're not really recoverable
       when 'non-user-code-problem'
         Backbone.Mediator.publish 'god:non-user-code-problem', problem: event.data.problem
@@ -80,9 +75,7 @@ module.exports = class Angel extends CocoClass
         else
           @fireWorker()
 
-      # Either the world finished simulating successfully, or we abort the worker.
-      when 'new-world'
-        @beholdWorld event.data.serialized, event.data.goalStates
+      # If it didn't finish simulating successfully, or we abort the worker.
       when 'abort'
         @say 'Aborted.', event.data
         clearTimeout @abortTimeout
@@ -91,6 +84,23 @@ module.exports = class Angel extends CocoClass
         _.remove @shared.busyAngels, @
         @doWork()
 
+      # We pay attention to certain progress indicators as the world loads.
+      when 'console-log'
+        @log event.data.args...
+      when 'user-code-problem'
+        Backbone.Mediator.publish 'god:user-code-problem', problem: event.data.problem
+      when 'world-load-progress-changed'
+        Backbone.Mediator.publish 'god:world-load-progress-changed', event.data
+        unless event.data.progress is 1 or @work.preload or @work.headless or @work.synchronous or @deserializationQueue.length or @shared.firstWorld
+          @worker.postMessage func: 'serializeFramesSoFar'  # Stream it!
+
+      # We have some or all of the frames serialized, so let's send the (partially?) simulated world to the Surface.
+      when 'some-frames-serialized', 'new-world'
+        deserializationArgs = [event.data.serialized, event.data.goalStates, event.data.startFrame, event.data.endFrame, @streamingWorld]
+        @deserializationQueue.push deserializationArgs
+        if @deserializationQueue.length is 1
+          @beholdWorld deserializationArgs...
+
       else
         @log 'Received unsupported message:', event.data
 
@@ -99,27 +109,37 @@ module.exports = class Angel extends CocoClass
     Backbone.Mediator.publish 'god:goals-calculated', goalStates: goalStates
     @finishWork() if @shared.headless
 
-  beholdWorld: (serialized, goalStates) ->
+  beholdWorld: (serialized, goalStates, startFrame, endFrame, streamingWorld) ->
     return if @aborting
     # Toggle BOX2D_ENABLED during deserialization so that if we have box2d in the namespace, the Collides Components still don't try to create bodies for deserialized Thangs upon attachment.
     window.BOX2D_ENABLED = false
-    World.deserialize serialized, @shared.worldClassMap, @shared.lastSerializedWorldFrames, @finishBeholdingWorld(goalStates)
+    World.deserialize serialized, @shared.worldClassMap, @shared.lastSerializedWorldFrames, @finishBeholdingWorld(goalStates), startFrame, endFrame, streamingWorld
     window.BOX2D_ENABLED = true
     @shared.lastSerializedWorldFrames = serialized.frames
 
   finishBeholdingWorld: (goalStates) -> (world) =>
     return if @aborting
-    world.findFirstChangedFrame @shared.world
-    @shared.world = world
-    errorCount = (t for t in @shared.world.thangs when t.errorsOut).length
-    Backbone.Mediator.publish 'god:new-world-created', world: world, firstWorld: @shared.firstWorld, errorCount: errorCount, goalStates: goalStates, team: me.team
-    for scriptNote in @shared.world.scriptNotes
-      Backbone.Mediator.publish scriptNote.channel, scriptNote.event
-    @shared.goalManager?.world = world
-    @finishWork()
+    @streamingWorld = world
+    finished = world.frames.length is world.totalFrames
+    firstChangedFrame = world.findFirstChangedFrame @shared.world
+    eventType = if finished then 'god:new-world-created' else 'god:streaming-world-updated'
+    if finished
+      @shared.world = world
+    Backbone.Mediator.publish eventType, world: world, firstWorld: @shared.firstWorld, goalStates: goalStates, team: me.team, firstChangedFrame: firstChangedFrame
+    if finished
+      for scriptNote in @shared.world.scriptNotes
+        Backbone.Mediator.publish scriptNote.channel, scriptNote.event
+      @shared.goalManager?.world = world
+      @finishWork()
+    else
+      @deserializationQueue.shift()  # Finished with this deserialization.
+      if deserializationArgs = @deserializationQueue[0]  # Start another?
+        @beholdWorld deserializationArgs...
 
   finishWork: ->
+    @streamingWorld = null
     @shared.firstWorld = false
+    @deserializationQueue = []
     @running = false
     _.remove @shared.busyAngels, @
     @doWork()
@@ -127,6 +147,7 @@ module.exports = class Angel extends CocoClass
   finalizePreload: ->
     @say 'Finalize preload.'
     @worker.postMessage func: 'finalizePreload'
+    @work.preload = false
 
   infinitelyLooped: =>
     @say 'On infinitely looped! Aborting?', @aborting
@@ -145,6 +166,7 @@ module.exports = class Angel extends CocoClass
       @say 'Running world...'
       @running = true
       @shared.busyAngels.push @
+      @deserializationQueue = []
       @worker.postMessage func: 'runWorld', args: @work
       clearTimeout @purgatoryTimer
       @say 'Infinite loop timer started at interval of', @infiniteLoopIntervalDuration
@@ -158,6 +180,8 @@ module.exports = class Angel extends CocoClass
     @say 'Aborting...'
     @running = false
     @work = null
+    @streamingWorld = null
+    @deserializationQueue = null
     _.remove @shared.busyAngels, @
     @abortTimeout = _.delay @fireWorker, @abortTimeoutDuration
     @aborting = true
@@ -184,6 +208,10 @@ module.exports = class Angel extends CocoClass
     @worker.addEventListener 'message', @onWorkerMessage
     @worker.creationTime = new Date()
 
+  onFlagEvent: (e) ->
+    return unless @running and @work.realTime
+    @worker.postMessage func: 'addFlagEvent', args: e
+
 
   #### Synchronous code for running worlds on main thread (profiling / IE9) ####
   simulateSync: (work) =>
diff --git a/app/lib/God.coffee b/app/lib/God.coffee
index ffe2ad726..de1f6b685 100644
--- a/app/lib/God.coffee
+++ b/app/lib/God.coffee
@@ -53,9 +53,9 @@ module.exports = class God extends CocoClass
   setWorldClassMap: (worldClassMap) -> @angelsShare.worldClassMap = worldClassMap
 
   onTomeCast: (e) ->
-    @createWorld e.spells, e.preload
+    @createWorld e.spells, e.preload, e.realTime
 
-  createWorld: (spells, preload=false) ->
+  createWorld: (spells, preload=false, realTime=false) ->
     console.log "#{@nick}: Let there be light upon #{@level.name}! (preload: #{preload})"
     userCodeMap = @getUserCodeMap spells
 
@@ -84,12 +84,14 @@ module.exports = class God extends CocoClass
       headless: @angelsShare.headless
       preload: preload
       synchronous: not Worker?  # Profiling world simulation is easier on main thread, or we are IE9.
+      realTime: realTime
     angel.workIfIdle() for angel in @angelsShare.angels
 
   getUserCodeMap: (spells) ->
     userCodeMap = {}
     for spellKey, spell of spells
       for thangID, spellThang of spell.thangs
+        continue if spellThang.thang?.programmableMethods[spell.name].cloneOf
         (userCodeMap[thangID] ?= {})[spell.name] = spellThang.aether.serialize()
     userCodeMap
 
diff --git a/app/lib/LevelBus.coffee b/app/lib/LevelBus.coffee
index 7ea0837c1..d79451500 100644
--- a/app/lib/LevelBus.coffee
+++ b/app/lib/LevelBus.coffee
@@ -196,7 +196,9 @@ module.exports = class LevelBus extends Bus
 
   onNewGoalStates: ({goalStates})->
     state = @session.get 'state'
-    unless utils.kindaEqual state.goalStates, goalStates # Only save when goals really change
+    unless utils.kindaEqual state.goalStates, goalStates  # Only save when goals really change
+      # TODO: this log doesn't capture when null-status goals are being set during world streaming. Where can they be coming from?
+      return console.error("Somehow trying to save null goal states!", goalStates) if _.find(goalStates, (gs) -> not gs.status)
       state.goalStates = goalStates
       @session.set 'state', state
       @changedSessionProperties.state = true
diff --git a/app/lib/LevelLoader.coffee b/app/lib/LevelLoader.coffee
index 48a980831..cc9a6dd12 100644
--- a/app/lib/LevelLoader.coffee
+++ b/app/lib/LevelLoader.coffee
@@ -70,14 +70,18 @@ module.exports = class LevelLoader extends CocoClass
     @listenToOnce @session, 'sync', ->
       @session.url = -> '/db/level.session/' + @id
       @loadDependenciesForSession(@session)
-    
+
     if @opponentSessionID
       opponentSession = new LevelSession().setURL "/db/level_session/#{@opponentSessionID}"
       @opponentSessionResource = @supermodel.loadModel(opponentSession, 'opponent_session')
       @opponentSession = @opponentSessionResource.model
       @listenToOnce @opponentSession, 'sync', @loadDependenciesForSession
-      
+
   loadDependenciesForSession: (session) ->
+    return if @levelID is 'sky-span'  # TODO
+    # TODO: I think this runs afoul of https://github.com/codecombat/codecombat/issues/1108
+    # TODO: this shouldn't happen when it's not a hero level, but we don't have level loaded yet,
+    # and the sessions are being created with default hero config regardless of whether it's a hero level.
     if heroConfig = session.get('heroConfig')
       url = "/db/thang.type/#{heroConfig.thangType}/version?project=name,components,original"
       @worldNecessities.push @maybeLoadURL(url, ThangType, 'thang')
@@ -107,7 +111,8 @@ module.exports = class LevelLoader extends CocoClass
     systemVersions = []
     articleVersions = []
 
-    for thang in @level.get('thangs') or []
+    flagThang = thangType: '53fa25f25bc220000052c2be', id: 'Placeholder Flag', components: []
+    for thang in (@level.get('thangs') or []).concat [flagThang]
       thangIDs.push thang.thangType
       @loadItemThangsEquippedByLevelThang(thang)
       for comp in thang.components or []
diff --git a/app/lib/LinkedInHandler.coffee b/app/lib/LinkedInHandler.coffee
index ed322f2c2..2a6be9a9e 100644
--- a/app/lib/LinkedInHandler.coffee
+++ b/app/lib/LinkedInHandler.coffee
@@ -14,7 +14,7 @@ module.exports = LinkedInHandler = class LinkedInHandler extends CocoClass
   onLinkedInLoaded: (e) ->
     IN.Event.on IN, 'auth', @onLinkedInAuth
 
-  onLinkedInAuth: (e) => console.log 'Authorized with LinkedIn'
+  onLinkedInAuth: (e) => #console.log 'Authorized with LinkedIn'
 
   constructEmployerAgreementObject: (cb) =>
     IN.API.Profile('me')
diff --git a/app/lib/scripts/ScriptManager.coffee b/app/lib/scripts/ScriptManager.coffee
index cea2b14ee..6983ac199 100644
--- a/app/lib/scripts/ScriptManager.coffee
+++ b/app/lib/scripts/ScriptManager.coffee
@@ -269,6 +269,7 @@ module.exports = ScriptManager = class ScriptManager extends CocoClass
     @publishNote(note)
 
   publishNote: (note) ->
+    Backbone.Mediator.publish 'playback:real-time-playback-ended', {}
     Backbone.Mediator.publish(note.channel, note.event)
 
   # ENDING NOTES
diff --git a/app/lib/services/linkedin.coffee b/app/lib/services/linkedin.coffee
index 9a6f0b37f..9134d77bb 100644
--- a/app/lib/services/linkedin.coffee
+++ b/app/lib/services/linkedin.coffee
@@ -1,6 +1,6 @@
 module.exports = initializeLinkedIn = ->
   window.linkedInAsyncInit = ->
-    console.log 'Linkedin async init success!'
+    #console.log 'Linkedin async init success!'
     Backbone.Mediator.publish 'linkedin-loaded'
 
   linkedInSnippet =
diff --git a/app/lib/simulator/Simulator.coffee b/app/lib/simulator/Simulator.coffee
index 184d7c7dc..0e5a6631e 100644
--- a/app/lib/simulator/Simulator.coffee
+++ b/app/lib/simulator/Simulator.coffee
@@ -184,7 +184,7 @@ module.exports = class Simulator extends CocoClass
     try
       @commenceSimulationAndSetupCallback()
     catch err
-      console.error 'There was an error in simulation:', err, "-- trying again in #{@retryDelayInSeconds} seconds"
+      console.error 'There was an error in simulation:', err, err.stack, "-- trying again in #{@retryDelayInSeconds} seconds"
       @simulateAnotherTaskAfterDelay()
 
   assignWorldAndLevelFromLevelLoaderAndDestroyIt: ->
diff --git a/app/lib/surface/CastingScreen.coffee b/app/lib/surface/CastingScreen.coffee
deleted file mode 100644
index 63eea858e..000000000
--- a/app/lib/surface/CastingScreen.coffee
+++ /dev/null
@@ -1,81 +0,0 @@
-CocoClass = require 'lib/CocoClass'
-
-module.exports = class CastingScreen extends CocoClass
-  subscriptions:
-    'tome:cast-spells': 'onCastingBegins'
-    'god:new-world-created': 'onCastingEnds'
-    'god:world-load-progress-changed': 'onWorldLoadProgressChanged'
-
-  constructor: (options) ->
-    super()
-    options ?= {}
-    @camera = options.camera
-    @layer = options.layer
-    console.error @toString(), 'needs a camera.' unless @camera
-    console.error @toString(), 'needs a layer.' unless @layer
-    @build()
-
-  onCastingBegins: (e) -> @show() unless e.preload
-  onCastingEnds: (e) -> @hide()
-
-  toString: -> '<CastingScreen>'
-
-  build: ->
-    @dimLayer = new createjs.Container()
-    @dimLayer.mouseEnabled = @dimLayer.mouseChildren = false
-    @dimLayer.layerIndex = -11
-    @dimLayer.addChild @dimScreen = new createjs.Shape()
-    @dimScreen.graphics.beginFill('rgba(0,0,0,0.5)').rect 0, 0, @camera.canvasWidth, @camera.canvasHeight
-    @dimLayer.alpha = 0
-    @layer.addChild @dimLayer
-    @dimLayer.addChild @makeProgressBar()
-    @dimLayer.addChild @makeCastingText()
-
-  onWorldLoadProgressChanged: (e) ->
-    if new Date().getTime() - @t0 > 500
-      createjs.Tween.removeTweens @progressBar
-      createjs.Tween.get(@progressBar).to({scaleX: e.progress}, 200)
-
-  makeProgressBar: ->
-    BAR_PIXEL_HEIGHT = 3
-    BAR_PCT_WIDTH = .75
-    pixelWidth = parseInt(@camera.canvasWidth * BAR_PCT_WIDTH)
-    pixelMargin = (@camera.canvasWidth - (@camera.canvasWidth * BAR_PCT_WIDTH)) / 2
-    barY = 3 * (@camera.canvasHeight / 5)
-
-    g = new createjs.Graphics()
-    g.beginFill(createjs.Graphics.getRGB(255, 255, 255))
-    g.drawRoundRect(0, 0, pixelWidth, BAR_PIXEL_HEIGHT, 3)
-    @progressBar = new createjs.Shape(g)
-    @progressBar.x = pixelMargin
-    @progressBar.y = barY
-    @progressBar.scaleX = 0
-    @dimLayer.addChild(@progressBar)
-
-  makeCastingText: ->
-    size = @camera.canvasHeight / 15
-    text = new createjs.Text('Casting', "#{size}px cursive", '#aaaaaa')
-    text.regX = text.getMeasuredWidth() / 2
-    text.regY = text.getMeasuredHeight() / 2
-    text.x = @camera.canvasWidth / 2
-    text.y = @camera.canvasHeight / 2
-    @text = text
-    return text
-
-  show: ->
-    return if @showing
-    @showing = true
-    @t0 = new Date().getTime()
-
-    @progressBar.scaleX = 0
-    @dimLayer.alpha = 0
-    createjs.Tween.removeTweens @dimLayer
-    createjs.Tween.get(@dimLayer).to({alpha: 1}, 500)
-
-  hide: ->
-    return unless @showing
-    @showing = false
-
-    createjs.Tween.removeTweens @progressBar
-    createjs.Tween.removeTweens @dimLayer
-    createjs.Tween.get(@dimLayer).to({alpha: 0}, 500)
diff --git a/app/lib/surface/CocoSprite.coffee b/app/lib/surface/CocoSprite.coffee
index 7f4db7220..a3dbc4130 100644
--- a/app/lib/surface/CocoSprite.coffee
+++ b/app/lib/surface/CocoSprite.coffee
@@ -320,6 +320,9 @@ module.exports = CocoSprite = class CocoSprite extends CocoClass
     [@imageObject.x, @imageObject.y] = [sup.x, sup.y]
     @lastPos = p1.copy?() or _.clone(p1)
     @hasMoved = true
+    if @thangType.get('name') is 'Flag' and not @notOfThisWorld
+      # Let the pending flags know we're here (but not this call stack, they need to delete themselves, and we may be iterating sprites).
+      _.defer => Backbone.Mediator.publish 'surface:flag-appeared', sprite: @
 
   updateBaseScale: ->
     scale = 1
@@ -519,7 +522,7 @@ module.exports = CocoSprite = class CocoSprite extends CocoClass
     @letterboxOn = e.on
 
   onMouseEvent: (e, ourEventName) ->
-    return if @letterboxOn
+    return if @letterboxOn or not @imageObject
     p = @imageObject
     p = p.parent while p.parent
     newEvent = sprite: @, thang: @thang, originalEvent: e, canvas:p.canvas
diff --git a/app/lib/surface/CoordinateDisplay.coffee b/app/lib/surface/CoordinateDisplay.coffee
index f650e09b1..155f7e7ac 100644
--- a/app/lib/surface/CoordinateDisplay.coffee
+++ b/app/lib/surface/CoordinateDisplay.coffee
@@ -35,10 +35,6 @@ module.exports = class CoordinateDisplay extends createjs.Container
   onMouseOut: (e) -> @mouseInBounds = false
 
   onMouseMove: (e) ->
-    if @mouseInBounds and key.shift
-      $('#surface').addClass('flag-cursor') unless $('#surface').hasClass('flag-cursor')
-    else if @mouseInBounds
-      $('#surface').removeClass('flag-cursor') if $('#surface').hasClass('flag-cursor')
     wop = @camera.screenToWorld x: e.x, y: e.y
     wop.x = Math.round(wop.x)
     wop.y = Math.round(wop.y)
diff --git a/app/lib/surface/FlagSprite.coffee b/app/lib/surface/FlagSprite.coffee
new file mode 100644
index 000000000..0c20b7ebf
--- /dev/null
+++ b/app/lib/surface/FlagSprite.coffee
@@ -0,0 +1,34 @@
+IndieSprite = require 'lib/surface/IndieSprite'
+{me} = require 'lib/auth'
+
+module.exports = class FlagSprite extends IndieSprite
+  subscriptions:
+    'surface:mouse-moved': 'onMouseMoved'
+
+  #shortcuts:
+
+  defaultPos: -> x: 20, y: 20, z: 1
+
+  constructor: (thangType, options) ->
+    super thangType, options
+    @toggleCursor options.isCursor
+
+  makeIndieThang: (thangType, options) ->
+    thang = super thangType, options
+    thang.width = thang.height = thang.depth = 2
+    thang.pos.z = 1
+    thang.isSelectable = false
+    thang.color = options.color
+    thang.team = options.team
+    thang
+
+  onMouseMoved: (e) ->
+    return unless @options.isCursor
+    wop = @options.camera.screenToWorld x: e.x, y: e.y
+    @thang.pos.x = wop.x
+    @thang.pos.y = wop.y
+
+  toggleCursor: (to) ->
+    @options.isCursor = to
+    @thang.alpha = if to then 0.33 else 0.67  # 1.0 is for flags that have been placed
+    @updateAlpha()
diff --git a/app/lib/surface/IndieSprite.coffee b/app/lib/surface/IndieSprite.coffee
index e66b90e16..a297b7508 100644
--- a/app/lib/surface/IndieSprite.coffee
+++ b/app/lib/surface/IndieSprite.coffee
@@ -1,8 +1,5 @@
-{me} = require('lib/auth')
 Thang = require 'lib/world/thang'
-Vector = require 'lib/world/vector'
 CocoSprite = require 'lib/surface/CocoSprite'
-Camera = require './Camera'
 
 module.exports = IndieSprite = class IndieSprite extends CocoSprite
   notOfThisWorld: true
@@ -11,16 +8,16 @@ module.exports = IndieSprite = class IndieSprite extends CocoSprite
     'note-group-ended': 'onNoteGroupEnded'
 
   constructor: (thangType, options) ->
-    options.thang = @makeIndieThang thangType, options.thangID, options.pos
+    options.thang = @makeIndieThang thangType, options
     super thangType, options
     @shadow = @thang
 
-  makeIndieThang: (thangType, thangID, pos) ->
-    @thang = thang = new Thang null, thangType.get('name'), thangID
+  makeIndieThang: (thangType, options) ->
+    @thang = thang = new Thang null, thangType.get('name'), options.thangID
     # Build needed results of what used to be Exists, Physical, Acts, and Selectable Components
     thang.exists = true
     thang.width = thang.height = thang.depth = 4
-    thang.pos = pos ? @defaultPos()
+    thang.pos = options.pos ? @defaultPos()
     thang.pos.z = thang.depth / 2
     thang.shape = 'ellipsoid'
     thang.rotation = 0
diff --git a/app/lib/surface/Label.coffee b/app/lib/surface/Label.coffee
index 959c92c13..30829d372 100644
--- a/app/lib/surface/Label.coffee
+++ b/app/lib/surface/Label.coffee
@@ -37,6 +37,8 @@ module.exports = class Label extends CocoClass
   build: ->
     @layer.removeChild @background if @background
     @layer.removeChild @label if @label
+    @label = null
+    @background = null
     return unless @text  # null or '' should both be skipped
     o = @buildLabelOptions()
     @layer.addChild @label = @buildLabel o
@@ -53,6 +55,17 @@ module.exports = class Label extends CocoClass
     @label.y = @background.y = @sprite.imageObject.y + offset.y
     null
 
+  show: ->
+    return unless @label
+    @layer.addChild @label
+    @layer.addChild @background
+    @layer.updateLayerOrder()
+
+  hide: ->
+    return unless @label
+    @layer.removeChild @background
+    @layer.removeChild @label
+
   buildLabelOptions: ->
     o = {}
     st = {dialogue: 'D', say: 'S', name: 'N'}[@style]
diff --git a/app/lib/surface/SpriteBoss.coffee b/app/lib/surface/SpriteBoss.coffee
index c5fd17c19..319358d58 100644
--- a/app/lib/surface/SpriteBoss.coffee
+++ b/app/lib/surface/SpriteBoss.coffee
@@ -3,6 +3,7 @@ CocoClass = require 'lib/CocoClass'
 Layer = require './Layer'
 IndieSprite = require 'lib/surface/IndieSprite'
 WizardSprite = require 'lib/surface/WizardSprite'
+FlagSprite = require 'lib/surface/FlagSprite'
 CocoSprite = require 'lib/surface/CocoSprite'
 Mark = require './Mark'
 Grid = require 'lib/world/Grid'
@@ -19,8 +20,13 @@ module.exports = class SpriteBoss extends CocoClass
     'level-lock-select': 'onSetLockSelect'
     'level:restarted': 'onLevelRestarted'
     'god:new-world-created': 'onNewWorld'
+    'god:streaming-world-updated': 'onNewWorld'
     'camera:dragged': 'onCameraDragged'
     'sprite:loaded': -> @update(true)
+    'level:flag-color-selected': 'onFlagColorSelected'
+    'level:flag-updated': 'onFlagUpdated'
+    'surface:flag-appeared': 'onFlagAppeared'
+    'surface:remove-selected-flag': 'onRemoveSelectedFlag'
 
   constructor: (@options) ->
     super()
@@ -36,6 +42,7 @@ module.exports = class SpriteBoss extends CocoClass
     @selfWizardSprite = null
     @createLayers()
     @spriteSheetCache = {}
+    @pendingFlags = []
 
   destroy: ->
     @removeSprite sprite for thangID, sprite of @sprites
@@ -112,7 +119,7 @@ module.exports = class SpriteBoss extends CocoClass
     sprite = @createWizardSprite thangID: opponent.id, name: opponent.name, codeLanguage: opponent.codeLanguage
     if not opponent.levelSlug or opponent.levelSlug is 'brawlwood'
       sprite.targetPos = if opponent.team is 'ogres' then {x: 52, y: 52} else {x: 28, y: 28}
-    else if opponent.levelSlug is 'dungeon-arena'
+    else if opponent.levelSlug in ['dungeon-arena', 'sky-span']
       sprite.targetPos = if opponent.team is 'ogres' then {x: 72, y: 39} else {x: 9, y: 39}
     else if opponent.levelSlug is 'criss-cross'
       sprite.targetPos = if opponent.team is 'ogres' then {x: 50, y: 12} else {x: 0, y: 40}
@@ -276,6 +283,7 @@ module.exports = class SpriteBoss extends CocoClass
     return @dragged = 0 if @dragged > 3
     @dragged = 0
     sprite = if e.sprite?.thang?.isSelectable then e.sprite else null
+    return if @flagCursorSprite and sprite?.thangType.get('name') is 'Flag'
     @selectSprite e, sprite
 
   onStageMouseDown: (e) ->
@@ -315,6 +323,45 @@ module.exports = class SpriteBoss extends CocoClass
         instance.addEventListener 'complete', ->
           Backbone.Mediator.publish 'thang-finished-talking', thang: sprite?.thang
 
+  onFlagColorSelected: (e) ->
+    @removeSprite @flagCursorSprite if @flagCursorSprite
+    @flagCursorSprite = null
+    for flagSprite in @spriteArray when flagSprite.thangType.get('name') is 'Flag'
+      flagSprite.imageObject.cursor = if e.color then 'crosshair' else 'pointer'
+    return unless e.color
+    @flagCursorSprite = new FlagSprite @thangTypeFor('Flag'), @createSpriteOptions(thangID: 'Flag Cursor', color: e.color, team: me.team, isCursor: true, pos: e.pos)
+    @addSprite @flagCursorSprite, @flagCursorSprite.thang.id, @spriteLayers['Floating']
+
+  onFlagUpdated: (e) ->
+    return unless e.active
+    pendingFlag = new FlagSprite @thangTypeFor('Flag'), @createSpriteOptions(thangID: 'Pending Flag ' + Math.random(), color: e.color, team: me.team, isCursor: false, pos: e.pos)
+    @addSprite pendingFlag, pendingFlag.thang.id, @spriteLayers['Floating']
+    @pendingFlags.push pendingFlag
+
+  onFlagAppeared: (e) ->
+    # Remove the pending flag that matches this one's color/team/position, and any color/team matches placed earlier.
+    t1 = e.sprite.thang
+    pending = (@pendingFlags ? []).slice()
+    foundExactMatch = false
+    for i in [pending.length - 1 .. 0] by -1
+      pendingFlag = pending[i]
+      t2 = pendingFlag.thang
+      matchedType = t1.color is t2.color and t1.team is t2.team
+      matched = matchedType and (foundExactMatch or Math.abs(t1.pos.x - t2.pos.x) < 0.00001 and Math.abs(t1.pos.y - t2.pos.y) < 0.00001)
+      if matched
+        foundExactMatch = true
+        @pendingFlags.splice(i, 1)
+        @removeSprite pendingFlag
+    e.sprite.imageObject.cursor = if @flagCursorSprite then 'crosshair' else 'pointer'
+    null
+
+  onRemoveSelectedFlag: (e) ->
+    # Remove the selected sprite if it's a flag, or any flag of the given color if a color is given.
+    flagSprite = _.find [@selectedSprite].concat(@spriteArray), (sprite) ->
+      sprite and sprite.thangType.get('name') is 'Flag' and sprite.thang.team is me.team and (sprite.thang.color is e.color or not e.color) and not sprite.notOfThisWorld
+    return unless flagSprite
+    Backbone.Mediator.publish 'surface:remove-flag', color: flagSprite.thang.color
+
   # Marks
 
   updateSelection: ->
diff --git a/app/lib/surface/Surface.coffee b/app/lib/surface/Surface.coffee
index bd6cf7df1..92715bd5a 100644
--- a/app/lib/surface/Surface.coffee
+++ b/app/lib/surface/Surface.coffee
@@ -8,7 +8,6 @@ CameraBorder = require './CameraBorder'
 Layer = require './Layer'
 Letterbox = require './Letterbox'
 Dimmer = require './Dimmer'
-CastingScreen = require './CastingScreen'
 PlaybackOverScreen = require './PlaybackOverScreen'
 DebugDisplay = require './DebugDisplay'
 CoordinateDisplay = require './CoordinateDisplay'
@@ -63,10 +62,15 @@ module.exports = Surface = class Surface extends CocoClass
     'level-set-surface-camera': 'onSetCamera'
     'level:restarted': 'onLevelRestarted'
     'god:new-world-created': 'onNewWorld'
+    'god:streaming-world-updated': 'onNewWorld'
     'tome:cast-spells': 'onCastSpells'
     'level-set-letterbox': 'onSetLetterbox'
     'application:idle-changed': 'onIdleChanged'
     'camera:zoom-updated': 'onZoomUpdated'
+    'playback:real-time-playback-started': 'onRealTimePlaybackStarted'
+    'playback:real-time-playback-ended': 'onRealTimePlaybackEnded'
+    'level:flag-color-selected': 'onFlagColorSelected'
+    #'god:world-load-progress-changed': -> console.log 'it is actually', @world.age
 
   shortcuts:
     'ctrl+\\, ⌘+\\': 'onToggleDebug'
@@ -82,7 +86,7 @@ module.exports = Surface = class Surface extends CocoClass
     @options = _.extend(@options, givenOptions) if givenOptions
     @initEasel()
     @initAudio()
-    @onResize = _.debounce @onResize, 500
+    @onResize = _.debounce @onResize, 250
     $(window).on 'resize', @onResize
     if @world.ended
       _.defer => @setWorld @world
@@ -96,7 +100,6 @@ module.exports = Surface = class Surface extends CocoClass
     @spriteBoss.destroy()
     @chooser?.destroy()
     @dimmer?.destroy()
-    @castingScreen?.destroy()
     @playbackOverScreen?.destroy()
     @stage.clear()
     @musicPlayer?.destroy()
@@ -115,14 +118,14 @@ module.exports = Surface = class Surface extends CocoClass
 
   setWorld: (@world) ->
     @worldLoaded = true
-    lastFrame = Math.min(@getCurrentFrame(), @world.totalFrames - 1)
+    lastFrame = Math.min(@getCurrentFrame(), @world.frames.length - 1)
     @world.getFrame(lastFrame).restoreState() unless @options.choosing
     @spriteBoss.world = @world
 
     @showLevel()
     @updateState true if @loaded
     # TODO: synchronize both ways of choosing whether to show coords (@world via UI System or @options via World Select modal)
-    if @world.showCoordinates and @options.coords
+    if @world.showCoordinates and @options.coords and not @coordinateDisplay
       @coordinateDisplay = new CoordinateDisplay camera: @camera
       @surfaceTextLayer.addChild @coordinateDisplay
     @onFrameChanged()
@@ -190,19 +193,19 @@ module.exports = Surface = class Surface extends CocoClass
   setProgress: (progress, scrubDuration=500) ->
     progress = Math.max(Math.min(progress, 1), 0.0)
 
+    @fastForwardingToFrame = null
     @scrubbing = true
     onTweenEnd = =>
       @scrubbingTo = null
       @scrubbing = false
       @scrubbingPlaybackSpeed = null
-      @fastForwarding = false
 
     if @scrubbingTo?
       # cut to the chase for existing tween
       createjs.Tween.removeTweens(@)
       @currentFrame = @scrubbingTo
 
-    @scrubbingTo = Math.min(Math.round(progress * @world.totalFrames), @world.totalFrames)
+    @scrubbingTo = Math.min(Math.round(progress * @world.frames.length), @world.frames.length)
     @scrubbingPlaybackSpeed = Math.sqrt(Math.abs(@scrubbingTo - @currentFrame) * @world.dt / (scrubDuration or 0.5))
     if scrubDuration
       t = createjs.Tween
@@ -244,7 +247,7 @@ module.exports = Surface = class Surface extends CocoClass
   getCurrentFrame: ->
     return Math.max(0, Math.min(Math.floor(@currentFrame), @world.frames.length - 1))
 
-  getProgress: -> @currentFrame / @world.totalFrames
+  getProgress: -> @currentFrame / @world.frames.length
 
   onLevelRestarted: (e) ->
     @setProgress 0, 0
@@ -286,26 +289,26 @@ module.exports = Surface = class Surface extends CocoClass
     @setPlayingCalled = true
     if @playing and @currentFrame >= (@world.totalFrames - 5)
       @currentFrame = 0
-    if @fastForwarding and not @playing
-      @setProgress @currentFrame / @world.totalFrames
+    if @fastForwardingToFrame and not @playing
+      @fastForwardingToFrame = null
 
   onSetTime: (e) ->
     toFrame = @currentFrame
     if e.time?
-      @worldLifespan = @world.totalFrames / @world.frameRate
+      @worldLifespan = @world.frames.length / @world.frameRate
       e.ratio = e.time / @worldLifespan
     if e.ratio?
-      toFrame = @world.totalFrames * e.ratio
+      toFrame = @world.frames.length * e.ratio
     if e.frameOffset
       toFrame += e.frameOffset
     if e.ratioOffset
-      toFrame += @world.totalFrames * e.ratioOffset
+      toFrame += @world.frames.length * e.ratioOffset
     unless _.isNumber(toFrame) and not _.isNaN(toFrame)
       return console.error('set-time event', e, 'produced invalid target frame', toFrame)
-    @setProgress(toFrame / @world.totalFrames, e.scrubDuration)
+    @setProgress(toFrame / @world.frames.length, e.scrubDuration)
 
   onFrameChanged: (force) ->
-    @currentFrame = Math.min(@currentFrame, @world.totalFrames)
+    @currentFrame = Math.min(@currentFrame, @world.frames.length)
     @debugDisplay?.updateFrame @currentFrame
     return if @currentFrame is @lastFrame and not force
     progress = @getProgress()
@@ -317,7 +320,7 @@ module.exports = Surface = class Surface extends CocoClass
       world: @world
     )
 
-    if @lastFrame < @world.totalFrames and @currentFrame >= @world.totalFrames - 1
+    if @lastFrame < @world.frames.length and @currentFrame >= @world.totalFrames - 1
       @ended = true
       @setPaused true
       Backbone.Mediator.publish 'surface:playback-ended'
@@ -353,48 +356,34 @@ module.exports = Surface = class Surface extends CocoClass
     return if e.preload
     @setPaused false if @ended
     @casting = true
-    @wasPlayingWhenCastingBegan = @playing
-    Backbone.Mediator.publish 'level-set-playing', {playing: false}
-    @setPlayingCalled = false # don't overwrite playing settings if they changed by, say, scripts
-
-    if @coordinateDisplay?
-      @surfaceTextLayer.removeChild @coordinateDisplay
-      @coordinateDisplay.destroy()
-
-    createjs.Tween.removeTweens(@surfaceLayer)
-    createjs.Tween.get(@surfaceLayer).to({alpha: 0.9}, 1000, createjs.Ease.getPowOut(4.0))
+    @setPlayingCalled = false  # Don't overwrite playing settings if they changed by, say, scripts.
+    @frameBeforeCast = @currentFrame
+    @setProgress 0
 
   onNewWorld: (event) ->
     return unless event.world.name is @world.name
     @casting = false
-    if @ended and not @wasPlayingWhenCastingBegan
-      @setPaused true
-    else
-      @spriteBoss.play()
+    @spriteBoss.play()
 
     # This has a tendency to break scripts that are waiting for playback to change when the level is loaded
     # so only run it after the first world is created.
-    Backbone.Mediator.publish 'level-set-playing', {playing: @wasPlayingWhenCastingBegan} unless event.firstWorld or @setPlayingCalled
+    Backbone.Mediator.publish 'level-set-playing', {playing: true} unless event.firstWorld or @setPlayingCalled
 
-    fastForwardTo = null
-    if @playing
-      fastForwardTo = Math.min event.world.firstChangedFrame, @currentFrame
-      @currentFrame = 0
-
-    createjs.Tween.removeTweens(@surfaceLayer)
-    f = =>
-      @setWorld event.world
-      @onFrameChanged(true)
-      if fastForwardTo and @playing
-        fastForwardToRatio = fastForwardTo / @world.totalFrames
-        fastForwardToTime = fastForwardTo * @world.dt
-        fastForwardSpeed = Math.max 4, fastForwardToTime / 3
-        @setProgress fastForwardToRatio, 1000 * fastForwardToTime / fastForwardSpeed
-        @fastForwarding = true
-    createjs.Tween.get(@surfaceLayer)
-      .to({alpha: 0.0}, 50)
-      .call(f)
-      .to({alpha: 1.0}, 2000, createjs.Ease.getPowOut(2.0))
+    @setWorld event.world
+    @onFrameChanged(true)
+    fastForwardBuffer = 2
+    if @playing and not @realTime and (ffToFrame = Math.min(event.firstChangedFrame, @frameBeforeCast, @world.frames.length)) and ffToFrame > @currentFrame + fastForwardBuffer * @world.frameRate
+      @fastForwardingToFrame = ffToFrame
+      @fastForwardingSpeed = Math.max 4, 4 * 90 / (@world.maxTotalFrames * @world.dt)
+    else if @realTime
+      lag = (@world.frames.length - 1) * @world.dt - @world.age
+      intendedLag = @world.realTimeBufferMax + @world.dt
+      if lag > intendedLag * 1.2
+        @fastForwardingToFrame = @world.frames.length - @world.realTimeBufferMax * @world.frameRate
+        @fastForwardingSpeed = lag / intendedLag
+      else
+        @fastForwardingToFrame = @fastForwardingSpeed = null
+      #console.log "on new world, lag", lag, "intended lag", intendedLag, "fastForwardingToFrame", @fastForwardingToFrame, "speed", @fastForwardingSpeed, "cause we are at", @world.age, "of", @world.frames.length * @world.dt
 
   # initialization
 
@@ -413,7 +402,6 @@ module.exports = Surface = class Surface extends CocoClass
     @surfaceLayer.addChild @cameraBorder = new CameraBorder bounds: @camera.bounds
     @screenLayer.addChild new Letterbox canvasWidth: canvasWidth, canvasHeight: canvasHeight
     @spriteBoss = new SpriteBoss camera: @camera, surfaceLayer: @surfaceLayer, surfaceTextLayer: @surfaceTextLayer, world: @world, thangTypes: @options.thangTypes, choosing: @options.choosing, navigateToSelection: @options.navigateToSelection, showInvisible: @options.showInvisible
-    @castingScreen ?= new CastingScreen camera: @camera, layer: @screenLayer
     @playbackOverScreen ?= new PlaybackOverScreen camera: @camera, layer: @screenLayer
     @stage.enableMouseOver(10)
     @stage.addEventListener 'stagemousemove', @onMouseMove
@@ -428,8 +416,17 @@ module.exports = Surface = class Surface extends CocoClass
   onResize: (e) =>
     oldWidth = parseInt @canvas.attr('width'), 10
     oldHeight = parseInt @canvas.attr('height'), 10
-    newWidth = @canvas.width()
-    newHeight = @canvas.height()
+    aspectRatio = oldWidth / oldHeight
+    pageWidth = $('#page-container').width() - 17  # 17px nano scroll bar
+    if @realTime
+      pageHeight = $('#page-container').height() - $('#control-bar-view').outerHeight() - $('#playback-view').outerHeight()
+      newWidth = Math.min pageWidth, pageHeight * aspectRatio
+      newHeight = newWidth / aspectRatio
+    else
+      newWidth = 0.55 * pageWidth
+      newHeight = newWidth / aspectRatio
+    @canvas.width newWidth
+    @canvas.height newHeight
     return unless newWidth > 0 and newHeight > 0
     #if InstallTrigger?  # Firefox rendering performance goes down as canvas size goes up
     #  newWidth = Math.min 924, newWidth
@@ -540,7 +537,9 @@ module.exports = Surface = class Surface extends CocoClass
   onMouseDown: (e) =>
     return if @disabled
     onBackground = not @stage.hitTest e.stageX, e.stageY
-    Backbone.Mediator.publish 'surface:stage-mouse-down', onBackground: onBackground, x: e.stageX, y: e.stageY, originalEvent: e
+    worldPos = @camera.screenToWorld x: e.stageX, y: e.stageY
+    event = onBackground: onBackground, x: e.stageX, y: e.stageY, originalEvent: e, worldPos: worldPos
+    Backbone.Mediator.publish 'surface:stage-mouse-down', event
 
   onMouseUp: (e) =>
     return if @disabled
@@ -569,14 +568,19 @@ module.exports = Surface = class Surface extends CocoClass
     # seems to be a bug where only one object can register with the Ticker...
     oldFrame = @currentFrame
     oldWorldFrame = Math.floor oldFrame
-    lastFrame = @world.totalFrames - 1
+    lastFrame = @world.frames.length - 1
     while true
       Dropper.tick()
       @trailmaster.tick() if @trailmaster
       # Skip some frame updates unless we're playing and not at end (or we haven't drawn much yet)
       frameAdvanced = (@playing and @currentFrame < lastFrame) or @totalFramesDrawn < 2
       if frameAdvanced and @playing
-        @currentFrame += @world.frameRate / @options.frameRate
+        advanceBy = @world.frameRate / @options.frameRate
+        if @fastForwardingToFrame and @currentFrame < @fastForwardingToFrame - advanceBy
+          advanceBy = Math.min(@currentFrame + advanceBy * @fastForwardingSpeed, @fastForwardingToFrame) - @currentFrame
+        else if @fastForwardingToFrame
+          @fastForwardingToFrame = @fastForwardingSpeed = null
+        @currentFrame += advanceBy
         @currentFrame = Math.min @currentFrame, lastFrame
       newWorldFrame = Math.floor @currentFrame
       worldFrameAdvanced = newWorldFrame isnt oldWorldFrame
@@ -603,8 +607,8 @@ module.exports = Surface = class Surface extends CocoClass
   restoreWorldState: ->
     frame = @world.getFrame(@getCurrentFrame())
     frame.restoreState()
-    current = Math.max(0, Math.min(@currentFrame, @world.totalFrames - 1))
-    if current - Math.floor(current) > 0.01
+    current = Math.max(0, Math.min(@currentFrame, @world.frames.length - 1))
+    if current - Math.floor(current) > 0.01 and Math.ceil(current) < @world.frames.length - 1
       next = Math.ceil current
       ratio = current % 1
       @world.frames[next].restorePartialState ratio if next > 1
@@ -614,13 +618,29 @@ module.exports = Surface = class Surface extends CocoClass
   updateState: (frameChanged) ->
     # world state must have been restored in @restoreWorldState
     @camera.updateZoom()
-    @spriteBoss.update frameChanged unless @casting
+    @spriteBoss.update frameChanged
     @dimmer?.setSprites @spriteBoss.sprites
 
   drawCurrentFrame: (e) ->
     ++@totalFramesDrawn
     @stage.update e
 
+  # Real-time playback
+  onRealTimePlaybackStarted: (e) ->
+    @realTime = true
+    @onResize()
+    @spriteBoss.selfWizardSprite?.toggle false
+
+  onRealTimePlaybackEnded: (e) ->
+    @realTime = false
+    @onResize()
+    @spriteBoss.selfWizardSprite?.toggle true
+    @canvas.removeClass 'flag-color-selected'
+
+  onFlagColorSelected: (e) ->
+    @canvas.toggleClass 'flag-color-selected', Boolean(e.color)
+    e.pos = @camera.screenToWorld @mouseScreenPos if @mouseScreenPos
+
   # paths - TODO: move to SpriteBoss? but only update on frame drawing instead of on every frame update?
 
   updatePaths: ->
diff --git a/app/lib/surface/WizardSprite.coffee b/app/lib/surface/WizardSprite.coffee
index 5d929147c..fc59f010d 100644
--- a/app/lib/surface/WizardSprite.coffee
+++ b/app/lib/surface/WizardSprite.coffee
@@ -1,5 +1,4 @@
 IndieSprite = require 'lib/surface/IndieSprite'
-Camera = require './Camera'
 {me} = require 'lib/auth'
 
 module.exports = class WizardSprite extends IndieSprite
@@ -35,12 +34,11 @@ module.exports = class WizardSprite extends IndieSprite
     @targetPos = @thang.pos
     if @isSelf
       @setNameLabel me.displayName()
-      @setColorHue me.get('wizardColor1')
     else if options.name
       @setNameLabel options.name
 
-  makeIndieThang: (thangType, thangID, pos) ->
-    thang = super thangType, thangID, pos
+  makeIndieThang: (thangType, options) ->
+    thang = super thangType, options
     thang.isSelectable = false
     thang.bobHeight = 0.75
     thang.bobTime = 2
@@ -59,6 +57,11 @@ module.exports = class WizardSprite extends IndieSprite
       name += " (#{@options.codeLanguage})"  # TODO: move on second line, capitalize properly
     super name
 
+  toggle: (to) ->
+    @imageObject?.visible = to
+    label[if to then 'show' else 'hide']() for name, label of @labels
+    mark.mark?.visible = to for name, mark of @marks
+
   onPlayerStatesChanged: (e) ->
     for playerID, state of e.states
       continue unless playerID is @thang.id
@@ -66,7 +69,6 @@ module.exports = class WizardSprite extends IndieSprite
       continue if playerID is me.id  # ignore changes for self wizard sprite
       @setNameLabel state.name
       continue unless state.wizard?
-      @setColorHue state.wizard.wizardColor1
       if targetID = state.wizard.targetSprite
         return console.warn 'Wizard Sprite couldn\'t find target sprite', targetID unless targetID of @options.sprites
         @setTarget @options.sprites[targetID]
@@ -91,17 +93,13 @@ module.exports = class WizardSprite extends IndieSprite
     @imageObject.scaleX = @imageObject.scaleY = @imageObject.alpha = 0
     createjs.Tween.get(@imageObject)
       .to({scaleX: 1, scaleY: 1, alpha: 1}, 1000, createjs.Ease.getPowInOut(2.2))
+    @labels.name?.show()
 
   animateOut: (callback) ->
     tween = createjs.Tween.get(@imageObject)
       .to({scaleX: 0, scaleY: 0, alpha: 0}, 1000, createjs.Ease.getPowInOut(2.2))
     tween.call(callback) if callback
-
-  setColorHue: (newColorHue) ->
-    # TODO: is this needed any more?
-    return if @colorHue is newColorHue
-    @colorHue = newColorHue
-    #@updateColorFilters()
+    @labels.name?.hide()
 
   setEditing: (@editing) ->
     if @editing
diff --git a/app/lib/world/thang.coffee b/app/lib/world/thang.coffee
index 64eb698c6..da69fdf0e 100644
--- a/app/lib/world/thang.coffee
+++ b/app/lib/world/thang.coffee
@@ -85,7 +85,7 @@ module.exports = class Thang
           throw new Error "Two types were specified for trackable property #{prop}: #{oldType} and #{type}."
 
   keepTrackedProperty: (prop) ->
-    # Hmm; can we do this faster?
+    # Wish we could do this faster, but I can't think of how.
     propIndex = @trackedPropertiesKeys.indexOf prop
     if propIndex isnt -1
       @trackedPropertiesUsed[propIndex] = true
@@ -147,6 +147,8 @@ module.exports = class Thang
     for trackedFinalProperty in @trackedFinalProperties ? []
       # TODO: take some (but not all) of serialize logic from ThangState to handle other types
       o.finalState[trackedFinalProperty] = @[trackedFinalProperty]
+    # Since we might keep tracked properties later during streaming, we need to know which we think are unused.
+    o.unusedTrackedPropertyKeys = (@trackedPropertiesKeys[propIndex] for used, propIndex in @trackedPropertiesUsed when not used)
     o
 
   @deserialize: (o, world, classMap) ->
@@ -154,6 +156,8 @@ module.exports = class Thang
     for [componentClassName, componentConfig] in o.components
       componentClass = classMap[componentClassName]
       t.addComponents [componentClass, componentConfig]
+    t.unusedTrackedPropertyKeys = o.unusedTrackedPropertyKeys
+    t.unusedTrackedPropertyValues = (t[prop] for prop in o.unusedTrackedPropertyKeys)
     for prop, val of o.finalState
       # TODO: take some (but not all) of deserialize logic from ThangState to handle other types
       t[prop] = val
@@ -164,7 +168,16 @@ module.exports = class Thang
 
   getSpriteOptions: ->
     colorConfigs = @world?.getTeamColors() or {}
-    options = {}
-    if @team and colorConfigs[@team]
-      options.colorConfig = {team: colorConfigs[@team]}
+    options = {colorConfig: {}}
+    if @team and teamColor = colorConfigs[@team]
+      options.colorConfig.team = teamColor
+    if @color and color = @grabColorConfig @color
+      options.colorConfig.color = color
     options
+
+  grabColorConfig: (color) ->
+    {
+      green: {hue: 0.33, saturation: 0.5, lightness: 0.5}
+      black: {hue: 0, saturation: 0, lightness: 0.25}
+      violet: {hue: 0.83, saturation: 0.5, lightness: 0.5}
+    }[color]
diff --git a/app/lib/world/thang_state.coffee b/app/lib/world/thang_state.coffee
index 611194cc3..117de1a97 100644
--- a/app/lib/world/thang_state.coffee
+++ b/app/lib/world/thang_state.coffee
@@ -64,7 +64,10 @@ module.exports = class ThangState
     # Get the property, whether we have it stored in @props or in @trackedPropertyValues. Optimize it.
     # Figured based on http://jsperf.com/object-vs-array-vs-native-linked-list/13 that it should be faster with small arrays to do the indexOf reads (each up to 24x faster) than to do a single object read, and then we don't have to maintain an extra @props object; just keep array
     propIndex = @trackedPropertyKeys.indexOf prop
-    return null if propIndex is -1
+    if propIndex is -1
+      initialPropIndex = @thang.unusedTrackedPropertyKeys.indexOf prop
+      return null if initialPropIndex is -1
+      return @thang.unusedTrackedPropertyValues[initialPropIndex]
     value = @props[propIndex]
     return value if value isnt undefined or @hasRestored
     return @props[propIndex] = @getStoredProp propIndex
@@ -73,22 +76,28 @@ module.exports = class ThangState
     # Restore trackedProperties' values to @thang, retrieving them from @trackedPropertyValues if needed. Optimize it.
     return @ if @thang._state is @ and not @thang.partialState
     unless @hasRestored  # Restoring in a deserialized World for first time
+      for prop, propIndex in @thang.unusedTrackedPropertyKeys when @trackedPropertyKeys.indexOf(prop) is -1
+        @thang[prop] = @thang.unusedTrackedPropertyValues[propIndex]
       props = []
       for prop, propIndex in @trackedPropertyKeys
         type = @trackedPropertyTypes[propIndex]
         storage = @trackedPropertyValues[propIndex]
-        props.push(@thang[prop] = @getStoredProp propIndex, type, storage)
+        props.push @thang[prop] = @getStoredProp propIndex, type, storage
         #console.log @frameIndex, @thang.id, prop, propIndex, type, storage, 'got', @thang[prop]
       @props = props
       @trackedPropertyTypes = @trackedPropertyValues = @specialKeysToValues = null  # leave @trackedPropertyKeys for indexing
       @hasRestored = true
     else  # Restoring later times
+      for prop, propIndex in @thang.unusedTrackedPropertyKeys when @trackedPropertyKeys.indexOf(prop) is -1
+        @thang[prop] = @thang.unusedTrackedPropertyValues[propIndex]
       for prop, propIndex in @trackedPropertyKeys
         @thang[prop] = @props[propIndex]
     @thang.partialState = false
     @
 
   restorePartial: (ratio) ->
+    # Don't think we need to worry about unusedTrackedPropertyValues here.
+    # If it's not tracked yet, it'll very rarely partially change between frames; we can afford to miss the first one.
     inverse = 1 - ratio
     for prop, propIndex in @trackedPropertyKeys when prop is 'pos' or prop is 'rotation'
       if @hasRestored
diff --git a/app/lib/world/world.coffee b/app/lib/world/world.coffee
index de540b991..e76ab2707 100644
--- a/app/lib/world/world.coffee
+++ b/app/lib/world/world.coffee
@@ -10,8 +10,11 @@ WorldScriptNote = require './world_script_note'
 {now, consolidateThangs, typedArraySupport} = require './world_utils'
 Component = require 'lib/world/component'
 System = require 'lib/world/system'
-PROGRESS_UPDATE_INTERVAL = 200
-DESERIALIZATION_INTERVAL = 20
+PROGRESS_UPDATE_INTERVAL = 100
+DESERIALIZATION_INTERVAL = 10
+REAL_TIME_BUFFER_MIN = 2 * PROGRESS_UPDATE_INTERVAL
+REAL_TIME_BUFFER_MAX = 3 * PROGRESS_UPDATE_INTERVAL
+REAL_TIME_BUFFERED_WAIT_INTERVAL = 0.5 * PROGRESS_UPDATE_INTERVAL
 ITEM_ORIGINAL = '53e12043b82921000051cdf9'
 
 module.exports = class World
@@ -21,7 +24,9 @@ module.exports = class World
   preloading: false  # Whether we are just preloading a world in case we soon cast it
   debugging: false  # Whether we are just rerunning to debug a world we've already cast
   headless: false  # Whether we are just simulating for goal states instead of all serialized results
+  framesSerializedSoFar: 0
   apiProperties: ['age', 'dt']
+  realTimeBufferMax: REAL_TIME_BUFFER_MAX / 1000
   constructor: (@userCodeMap, classMap) ->
     # classMap is needed for deserializing Worlds, Thangs, and other classes
     @classMap = classMap ? {Vector: Vector, Rectangle: Rectangle, Thang: Thang, Ellipse: Ellipse, LineSegment: LineSegment}
@@ -33,6 +38,7 @@ module.exports = class World
     @systems = []
     @systemMap = {}
     @scriptNotes = []
+    @flagHistory = []
     @rand = new Rand 0  # Existence System may change this seed
     @frames = [new WorldFrame(@, 0)]
 
@@ -65,10 +71,11 @@ module.exports = class World
         @thangs[i] = thang
     @thangMap[thang.id] = thang
 
-  thangDialogueSounds: ->
-    if @frames.length < @totalFrames then throw new Error('World should be over before grabbing dialogue')
+  thangDialogueSounds: (startFrame=0) ->
+    return [] unless startFrame < @frames.length
     [sounds, seen] = [[], {}]
-    for frame in @frames
+    for frameIndex in [startFrame ... @frames.length]
+      frame = @frames[frameIndex]
       for thangID, state of frame.thangStateMap
         continue unless state.thang.say and sayMessage = state.getStateForProp 'sayMessage'
         soundKey = state.thang.spriteName + ':' + sayMessage
@@ -85,50 +92,30 @@ module.exports = class World
 
   loadFrames: (loadedCallback, errorCallback, loadProgressCallback, skipDeferredLoading, loadUntilFrame) ->
     return if @aborted
-    unless @thangs.length
-      console.log 'Warning: loadFrames called on empty World (no thangs).'
+    console.log 'Warning: loadFrames called on empty World (no thangs).' unless @thangs.length
     t1 = now()
     @t0 ?= t1
-    if loadUntilFrame
-      frameToLoadUntil = loadUntilFrame + 1
-    else
-      frameToLoadUntil = @totalFrames
+    @worldLoadStartTime ?= t1
+    @lastRealTimeUpdate ?= 0
+    continueLaterFn = =>
+      @loadFrames(loadedCallback, errorCallback, loadProgressCallback, skipDeferredLoading, loadUntilFrame) unless @destroyed
+    frameToLoadUntil = if loadUntilFrame then loadUntilFrame + 1 else @totalFrames  # Might stop early if debugging.
     i = @frames.length
-    while i < frameToLoadUntil
-      if @debugging
-        for thang in @thangs when thang.isProgrammable
-          userCode = @userCodeMap[thang.id] ? {}
-          for methodName, aether of userCode
-            framesToLoadFlowBefore = if methodName is 'plan' or methodName is 'makeBid' then 200 else 1  # Adjust if plan() is taking even longer
-            aether._shouldSkipFlow = i < loadUntilFrame - framesToLoadFlowBefore
+    while i < frameToLoadUntil and i < @totalFrames
+      return unless @shouldContinueLoading t1, loadProgressCallback, skipDeferredLoading, continueLaterFn
+      @adjustFlowSettings loadUntilFrame if @debugging
       try
         @getFrame(i)
-        ++i  # increment this after we have succeeded in getting the frame, otherwise we'll have to do that frame again
+        ++i  # Increment this after we have succeeded in getting the frame, otherwise we'll have to do that frame again
       catch error
-        # Not an Aether.errors.UserCodeError; maybe we can't recover
-        @addError error
+        @addError error  # Not an Aether.errors.UserCodeError; maybe we can't recover
       unless @preloading or @debugging
         for error in (@unhandledRuntimeErrors ? [])
           return unless errorCallback error  # errorCallback tells us whether the error is recoverable
         @unhandledRuntimeErrors = []
-      t2 = now()
-      if t2 - t1 > PROGRESS_UPDATE_INTERVAL
-        loadProgressCallback? i / @totalFrames unless @preloading
-        t1 = t2
-        if t2 - @t0 > 1000
-          console.log '  Loaded', i, 'of', @totalFrames, '(+' + (t2 - @t0).toFixed(0) + 'ms)'
-          @t0 = t2
-        continueFn = =>
-          return if @destroyed
-          if loadUntilFrame
-            @loadFrames(loadedCallback,errorCallback,loadProgressCallback, skipDeferredLoading, loadUntilFrame)
-          else
-            @loadFrames(loadedCallback, errorCallback, loadProgressCallback, skipDeferredLoading)
-        if skipDeferredLoading
-          continueFn()
-        else
-          setTimeout(continueFn, 0)
-        return
+    @finishLoadingFrames loadProgressCallback, loadedCallback
+
+  finishLoadingFrames: (loadProgressCallback, loadedCallback) ->
     unless @debugging
       @ended = true
       system.finish @thangs for system in @systems
@@ -136,6 +123,53 @@ module.exports = class World
       loadProgressCallback? 1
       loadedCallback()
 
+  shouldDelayRealTimeSimulation: (t) ->
+    return false unless @realTime
+    timeSinceStart = t - @worldLoadStartTime
+    timeLoaded = @frames.length * @dt * 1000
+    timeBuffered = timeLoaded - timeSinceStart
+    timeBuffered > REAL_TIME_BUFFER_MAX
+
+  shouldUpdateRealTimePlayback: (t) ->
+    return false unless @realTime
+    return false if @frames.length * @dt is @lastRealTimeUpdate
+    timeLoaded = @frames.length * @dt * 1000
+    timeSinceStart = t - @worldLoadStartTime
+    remainingBuffer = @lastRealTimeUpdate * 1000 - timeSinceStart
+    remainingBuffer < REAL_TIME_BUFFER_MIN
+
+  shouldContinueLoading: (t1, loadProgressCallback, skipDeferredLoading, continueLaterFn) ->
+    t2 = now()
+    if @realTime
+      shouldUpdateProgress = @shouldUpdateRealTimePlayback t2
+      shouldDelayRealTimeSimulation = not shouldUpdateProgress and @shouldDelayRealTimeSimulation t2
+    else
+      shouldUpdateProgress = t2 - t1 > PROGRESS_UPDATE_INTERVAL
+      shouldDelayRealTimeSimulation = false
+    return true unless shouldUpdateProgress or shouldDelayRealTimeSimulation
+    # Stop loading frames for now; continue in a moment.
+    if shouldUpdateProgress
+      @lastRealTimeUpdate = @frames.length * @dt if @realTime
+      #console.log 'we think it is now', (t2 - @worldLoadStartTime) / 1000, 'so delivering', @lastRealTimeUpdate
+      loadProgressCallback? @frames.length / @totalFrames unless @preloading
+    t1 = t2
+    if t2 - @t0 > 1000
+      console.log '  Loaded', @frames.length, 'of', @totalFrames, '(+' + (t2 - @t0).toFixed(0) + 'ms)' unless @realTime
+      @t0 = t2
+    if skipDeferredLoading
+      continueLaterFn()
+    else
+      delay = if shouldDelayRealTimeSimulation then REAL_TIME_BUFFERED_WAIT_INTERVAL else 0
+      setTimeout continueLaterFn, delay
+    false
+
+  adjustFlowSettings: (loadUntilFrame) ->
+    for thang in @thangs when thang.isProgrammable
+      userCode = @userCodeMap[thang.id] ? {}
+      for methodName, aether of userCode
+        framesToLoadFlowBefore = if methodName is 'plan' or methodName is 'makeBid' then 200 else 1  # Adjust if plan() is taking even longer
+        aether._shouldSkipFlow = @frames.length < loadUntilFrame - framesToLoadFlowBefore
+
   finalizePreload: (loadedCallback) ->
     @preloading = false
     loadedCallback() if @ended
@@ -143,6 +177,9 @@ module.exports = class World
   abort: ->
     @aborted = true
 
+  addFlagEvent: (flagEvent) ->
+    @flagHistory.push flagEvent
+
   loadFromLevel: (level, willSimulate=true) ->
     @levelComponents = level.levelComponents
     @thangTypes = level.thangTypes
@@ -289,7 +326,9 @@ module.exports = class World
 
   serialize: ->
     # Code hotspot; optimize it
-    if @frames.length < @totalFrames then throw new Error('World Should Be Over Before Serialization')
+    startFrame = @framesSerializedSoFar
+    endFrame = @frames.length
+    #console.log "... world serializing frames from", startFrame, "to", endFrame, "of", @totalFrames
     [transferableObjects, nontransferableObjects] = [0, 0]
     o = {totalFrames: @totalFrames, maxTotalFrames: @maxTotalFrames, frameRate: @frameRate, dt: @dt, victory: @victory, userCodeMap: {}, trackedProperties: {}}
     o.trackedProperties[prop] = @[prop] for prop in @trackedProperties or []
@@ -305,12 +344,14 @@ module.exports = class World
     o.trackedPropertiesPerThangKeys = []
     o.trackedPropertiesPerThangTypes = []
     trackedPropertiesPerThangValues = []  # We won't send these, just the offsets and the storage buffer
-    o.trackedPropertiesPerThangValuesOffsets = []  # Needed to reconstruct ArrayBufferViews on other end, since Firefox has bugs transfering those: https://bugzilla.mozilla.org/show_bug.cgi?id=841904 and https://bugzilla.mozilla.org/show_bug.cgi?id=861925
+    o.trackedPropertiesPerThangValuesOffsets = []  # Needed to reconstruct ArrayBufferViews on other end, since Firefox has bugs transfering those: https://bugzilla.mozilla.org/show_bug.cgi?id=841904 and https://bugzilla.mozilla.org/show_bug.cgi?id=861925  # Actually, as of January 2014, it should be fixed. So we could try to undo the workaround.
     transferableStorageBytesNeeded = 0
-    nFrames = @frames.length
+    nFrames = endFrame - startFrame
+    streaming = nFrames < @totalFrames
     for thang in @thangs
       # Don't serialize empty trackedProperties for stateless Thangs which haven't changed (like obstacles).
-      # Check both, since sometimes people mark stateless Thangs but don't change them, and those should still be tracked, and the inverse doesn't work on the other end (we'll just think it doesn't exist then).
+      # Check both, since sometimes people mark stateless Thangs but then change them, and those should still be tracked, and the inverse doesn't work on the other end (we'll just think it doesn't exist then).
+      # If streaming the world, a thang marked stateless that actually change will get messed up. I think.
       continue if thang.stateless and not _.some(thang.trackedPropertiesUsed, Boolean)
       o.trackedPropertiesThangIDs.push thang.id
       trackedPropertiesIndices = []
@@ -357,8 +398,8 @@ module.exports = class World
 
     t1 = now()
     o.frameHashes = []
-    for frame, frameIndex in @frames
-      o.frameHashes.push frame.serialize(frameIndex, o.trackedPropertiesThangIDs, o.trackedPropertiesPerThangIndices, o.trackedPropertiesPerThangTypes, trackedPropertiesPerThangValues, o.specialValuesToKeys, o.specialKeysToValues)
+    for frameIndex in [startFrame ... endFrame]
+      o.frameHashes.push @frames[frameIndex].serialize(frameIndex - startFrame, o.trackedPropertiesThangIDs, o.trackedPropertiesPerThangIndices, o.trackedPropertiesPerThangTypes, trackedPropertiesPerThangValues, o.specialValuesToKeys, o.specialKeysToValues)
     t2 = now()
 
     unless typedArraySupport
@@ -368,29 +409,35 @@ module.exports = class World
           flattened.push value
       o.storageBuffer = flattened
 
-    #console.log 'Allocating memory:', (t1 - t0).toFixed(0), 'ms; assigning values:', (t2 - t1).toFixed(0), 'ms, so', ((t2 - t1) / @frames.length).toFixed(3), 'ms per frame'
+    #console.log 'Allocating memory:', (t1 - t0).toFixed(0), 'ms; assigning values:', (t2 - t1).toFixed(0), 'ms, so', ((t2 - t1) / nFrames).toFixed(3), 'ms per frame for', nFrames, 'frames'
     #console.log 'Got', transferableObjects, 'transferable objects and', nontransferableObjects, 'nontransferable; stored', transferableStorageBytesNeeded, 'bytes transferably'
 
     o.thangs = (t.serialize() for t in @thangs.concat(@extraneousThangs ? []))
     o.scriptNotes = (sn.serialize() for sn in @scriptNotes)
     if o.scriptNotes.length > 200
       console.log 'Whoa, serializing a lot of WorldScriptNotes here:', o.scriptNotes.length
-    {serializedWorld: o, transferableObjects: [o.storageBuffer]}
+    {serializedWorld: o, transferableObjects: [o.storageBuffer], startFrame: startFrame, endFrame: endFrame}
 
-  @deserialize: (o, classMap, oldSerializedWorldFrames, finishedWorldCallback) ->
+  @deserialize: (o, classMap, oldSerializedWorldFrames, finishedWorldCallback, startFrame, endFrame, streamingWorld) ->
     # Code hotspot; optimize it
     #console.log 'Deserializing', o, 'length', JSON.stringify(o).length
     #console.log JSON.stringify(o)
     #console.log 'Got special keys and values:', o.specialValuesToKeys, o.specialKeysToValues
     perf = {}
     perf.t0 = now()
-    w = new World o.userCodeMap, classMap
+    nFrames = endFrame - startFrame
+    w = streamingWorld ? new World o.userCodeMap, classMap
     [w.totalFrames, w.maxTotalFrames, w.frameRate, w.dt, w.scriptNotes, w.victory] = [o.totalFrames, o.maxTotalFrames, o.frameRate, o.dt, o.scriptNotes ? [], o.victory]
     w[prop] = val for prop, val of o.trackedProperties
 
     perf.t1 = now()
-    w.thangs = (Thang.deserialize(thang, w, classMap) for thang in o.thangs)
-    w.setThang thang for thang in w.thangs
+    if w.thangs.length
+      for thangConfig in o.thangs when not w.thangMap[thangConfig.id]
+        w.thangs.push thang = Thang.deserialize(thangConfig, w, classMap)
+        w.setThang thang
+    else
+      w.thangs = (Thang.deserialize(thang, w, classMap) for thang in o.thangs)
+      w.setThang thang for thang in w.thangs
     w.scriptNotes = (WorldScriptNote.deserialize(sn, w, classMap) for sn in o.scriptNotes)
     perf.t2 = now()
 
@@ -400,7 +447,7 @@ module.exports = class World
       o.trackedPropertiesPerThangValues.push (trackedPropertiesValues = [])
       trackedPropertiesValuesOffsets = o.trackedPropertiesPerThangValuesOffsets[thangIndex]
       for type, propIndex in trackedPropertyTypes
-        storage = ThangState.createArrayForType(type, o.totalFrames, o.storageBuffer, trackedPropertiesValuesOffsets[propIndex])[0]
+        storage = ThangState.createArrayForType(type, nFrames, o.storageBuffer, trackedPropertiesValuesOffsets[propIndex])[0]
         unless typedArraySupport
           # This could be more efficient
           i = trackedPropertiesValuesOffsets[propIndex]
@@ -409,45 +456,52 @@ module.exports = class World
     perf.t3 = now()
 
     perf.batches = 0
-    w.frames = []
-    _.delay @deserializeSomeFrames, 1, o, w, finishedWorldCallback, perf
+    perf.framesCPUTime = 0
+    w.frames = [] unless streamingWorld
+    clearTimeout @deserializationTimeout if @deserializationTimeout
+    @deserializationTimeout = _.delay @deserializeSomeFrames, 1, o, w, finishedWorldCallback, perf, startFrame, endFrame
 
   # Spread deserialization out across multiple calls so the interface stays responsive
-  @deserializeSomeFrames: (o, w, finishedWorldCallback, perf) =>
+  @deserializeSomeFrames: (o, w, finishedWorldCallback, perf, startFrame, endFrame) =>
     ++perf.batches
     startTime = now()
-    for frameIndex in [w.frames.length ... o.totalFrames]
-      w.frames.push WorldFrame.deserialize(w, frameIndex, o.trackedPropertiesThangIDs, o.trackedPropertiesThangs, o.trackedPropertiesPerThangKeys, o.trackedPropertiesPerThangTypes, o.trackedPropertiesPerThangValues, o.specialKeysToValues, o.frameHashes[frameIndex])
-      if (now() - startTime) > DESERIALIZATION_INTERVAL
-        _.delay @deserializeSomeFrames, 1, o, w, finishedWorldCallback, perf
+    for frameIndex in [w.frames.length ... endFrame]
+      w.frames.push WorldFrame.deserialize(w, frameIndex - startFrame, o.trackedPropertiesThangIDs, o.trackedPropertiesThangs, o.trackedPropertiesPerThangKeys, o.trackedPropertiesPerThangTypes, o.trackedPropertiesPerThangValues, o.specialKeysToValues, o.frameHashes[frameIndex - startFrame], w.dt * frameIndex)
+      elapsed = now() - startTime
+      if elapsed > DESERIALIZATION_INTERVAL and frameIndex < endFrame - 1
+        #console.log "  Deserialization not finished, let's do it again soon. Have:", w.frames.length, ", wanted from", startFrame, "to", endFrame
+        perf.framesCPUTime += elapsed
+        @deserializationTimeout = _.delay @deserializeSomeFrames, 1, o, w, finishedWorldCallback, perf, startFrame, endFrame
         return
-    @finishDeserializing w, finishedWorldCallback, perf
+    @deserializationTimeout = null
+    perf.framesCPUTime += elapsed
+    @finishDeserializing w, finishedWorldCallback, perf, startFrame, endFrame
 
-  @finishDeserializing: (w, finishedWorldCallback, perf) ->
+  @finishDeserializing: (w, finishedWorldCallback, perf, startFrame, endFrame) ->
     perf.t4 = now()
     w.ended = true
-    w.getFrame(w.totalFrames - 1).restoreState()
-    perf.t5 = now()
-    console.log 'Deserialization:', (perf.t5 - perf.t0).toFixed(0) + 'ms (' + ((perf.t5 - perf.t0) / w.frames.length).toFixed(3) + 'ms per frame).', perf.batches, 'batches.'
+    nFrames = endFrame - startFrame
+    totalCPUTime = perf.t3 - perf.t0 + perf.framesCPUTime
+    #console.log 'Deserialization:', totalCPUTime.toFixed(0) + 'ms (' + (totalCPUTime / nFrames).toFixed(3) + 'ms per frame).', perf.batches, 'batches. Did', startFrame, 'to', endFrame, 'in', (perf.t4 - perf.t0).toFixed(0) + 'ms wall clock time.'
     if false
       console.log '  Deserializing--constructing new World:', (perf.t1 - perf.t0).toFixed(2) + 'ms'
       console.log '  Deserializing--Thangs and ScriptNotes:', (perf.t2 - perf.t1).toFixed(2) + 'ms'
       console.log '  Deserializing--reallocating memory:', (perf.t3 - perf.t2).toFixed(2) + 'ms'
-      console.log '  Deserializing--WorldFrames:', (perf.t4 - perf.t3).toFixed(2) + 'ms'
-      console.log '  Deserializing--restoring last WorldFrame:', (perf.t5 - perf.t4).toFixed(2) + 'ms'
+      console.log '  Deserializing--WorldFrames:', (perf.t4 - perf.t3).toFixed(2) + 'ms wall clock time,', (perf.framesCPUTime).toFixed(2) + 'ms CPU time'
     finishedWorldCallback w
 
   findFirstChangedFrame: (oldWorld) ->
-    return @firstChangedFrame = 0 unless oldWorld
+    return 0 unless oldWorld
     for newFrame, i in @frames
       oldFrame = oldWorld.frames[i]
-      break unless oldFrame and newFrame.hash is oldFrame.hash
-    @firstChangedFrame = i
-    if @frames[i]
-      console.log 'First changed frame is', @firstChangedFrame, 'with hash', @frames[i].hash, 'compared to', oldWorld.frames[i]?.hash
-    else
-      console.log 'No frames were changed out of all', @frames.length
-    @firstChangedFrame
+      break unless oldFrame and ((newFrame.hash is oldFrame.hash) or not newFrame.hash? or not oldFrame.hash?)  # undefined gets in there when streaming at the last frame of each batch for some reason
+    firstChangedFrame = i
+    if @frames.length is @totalFrames
+      if @frames[i]
+        console.log 'First changed frame is', firstChangedFrame, 'with hash', @frames[i].hash, 'compared to', oldWorld.frames[i]?.hash
+      else
+        console.log 'No frames were changed out of all', @frames.length
+    firstChangedFrame
 
   pointsForThang: (thangID, frameStart=0, frameEnd=null, camera=null, resolution=4) ->
     # Optimized
diff --git a/app/lib/world/world_frame.coffee b/app/lib/world/world_frame.coffee
index 2ab99f153..d1386b718 100644
--- a/app/lib/world/world_frame.coffee
+++ b/app/lib/world/world_frame.coffee
@@ -60,9 +60,9 @@ module.exports = class WorldFrame
         thangState.serialize(frameIndex, trackedPropertiesPerThangIndices[thangIndex], trackedPropertiesPerThangTypes[thangIndex], trackedPropertiesPerThangValues[thangIndex], specialValuesToKeys, specialKeysToValues)
     @hash
 
-  @deserialize: (world, frameIndex, trackedPropertiesThangIDs, trackedPropertiesThangs, trackedPropertiesPerThangKeys, trackedPropertiesPerThangTypes, trackedPropertiesPerThangValues, specialKeysToValues, hash) ->
+  @deserialize: (world, frameIndex, trackedPropertiesThangIDs, trackedPropertiesThangs, trackedPropertiesPerThangKeys, trackedPropertiesPerThangTypes, trackedPropertiesPerThangValues, specialKeysToValues, hash, age) ->
     # Optimize
-    wf = new WorldFrame null, world.dt * frameIndex
+    wf = new WorldFrame null, age
     wf.world = world
     wf.hash = hash
     for thangID, thangIndex in trackedPropertiesThangIDs
diff --git a/app/locale/en.coffee b/app/locale/en.coffee
index e649a439b..27c340771 100644
--- a/app/locale/en.coffee
+++ b/app/locale/en.coffee
@@ -498,7 +498,9 @@
     space: "Space"
     enter: "Enter"
     escape: "Escape"
+    shift: "Shift"
     cast_spell: "Cast current spell."
+    run_real_time: "Run in real time."
     continue_script: "Continue past current script."
     skip_scripts: "Skip past all skippable scripts."
     toggle_playback: "Toggle play/pause."
diff --git a/app/locale/pt-PT.coffee b/app/locale/pt-PT.coffee
index 23c7c559a..59bdd8825 100644
--- a/app/locale/pt-PT.coffee
+++ b/app/locale/pt-PT.coffee
@@ -874,7 +874,7 @@ module.exports = nativeDescription: "Português (Portugal)", englishDescription:
     tournament_ended: "O Torneio acabou"
     tournament_rules: "Regras do Torneio"
     tournament_blurb: "Escreva código, recolha ouro, construa exércitos, esmague inimigos, ganhe prémios e melhore a sua carreira no nosso torneio $40,000 Greed! Confira os detalhes"
-#    tournament_blurb_criss_cross: "Win bids, construct paths, outwit opponents, grab gems, and upgrade your career in our Criss-Cross tournament! Check out the details"
+    tournament_blurb_criss_cross: "Ganhe ofertas, construa caminhos, supere os adversários, apanhe gemas e melhore a sua carreira no nosso torneio Criss-Cross! Confira os detalhes"
     tournament_blurb_blog: "no nosso blog"
     rules: "Regras"
     winners: "Vencedores"
@@ -945,7 +945,7 @@ module.exports = nativeDescription: "Português (Portugal)", englishDescription:
     candidate_sessions: "Sessões de Candidatos"
     user_remark: "Observação do Utilizador"
     versions: "Versões"
-#    items: "Items"
+    items: "Itens"
 
   delta:
     added: "Adicionados/as"
diff --git a/app/locale/zh-HANS.coffee b/app/locale/zh-HANS.coffee
index c9d1172c6..9aa3cb865 100644
--- a/app/locale/zh-HANS.coffee
+++ b/app/locale/zh-HANS.coffee
@@ -26,14 +26,14 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     minutes: "分钟"
     hour: "小时"
     hours: "小时"
-#    day: "day"
-#    days: "days"
-#    week: "week"
-#    weeks: "weeks"
-#    month: "month"
-#    months: "months"
-#    year: "year"
-#    years: "years"
+    day: "日"
+    days: "日"
+    week: "星期"
+    weeks: "星期"
+    month: "月"
+    months: "月"
+    year: "年"
+    years: "年"
 
   modal:
     close: "关闭"
@@ -49,9 +49,9 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     blog: "博客"
     forum: "论坛"
     account: "账号"
-#    profile: "Profile"
-#    stats: "Stats"
-#    code: "Code"
+    profile: "资料"
+    stats: "成就"
+    code: "代码"
     admin: "管理"
     home: "首页"
     contribute: "贡献"
@@ -90,7 +90,7 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     sign_up: "注册"
     log_in: "登录"
     social_signup: "或者，你可以通过Facebook或G+注册："
-#    required: "You need to log in before you can go that way."
+    required: "在做这件事情之前你必须先注册。"
 
   home:
     slogan: "通过游戏学习编程"
@@ -98,17 +98,17 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     no_mobile: "CodeCombat 不是针对手机设备设计的，所以可能无法达到最好的体验！"
     play: "开始游戏"
     old_browser: "噢, 你的浏览器太老了, 不能运行CodeCombat. 抱歉!"
-    old_browser_suffix: "尽管你可以多试几次, 但也许不会管用."
+    old_browser_suffix: "你可以继续重试下去，但八成不起作用，更新浏览器吧亲～"
     campaign: "战役模式"
     for_beginners: "适合初学者"
     multiplayer: "多人游戏"
     for_developers: "适合开发者"
-#    javascript_blurb: "The language of the web. Great for writing websites, web apps, HTML5 games, and servers."
-#    python_blurb: "Simple yet powerful, Python is a great general purpose programming language."
-#    coffeescript_blurb: "Nicer JavaScript syntax."
-#    clojure_blurb: "A modern Lisp."
-#    lua_blurb: "Game scripting language."
-#    io_blurb: "Simple but obscure."
+    javascript_blurb: "为web开发而生的语言。 非常适合制作网站, 网站apps, HTML5游戏或开发服务器。"
+    python_blurb: "简单而强大, Python是一个伟大的通用编程语言。"
+    coffeescript_blurb: "一种更好的JavaScript语法."
+    clojure_blurb: "一种现代的列表处理语言。"
+    lua_blurb: "一种游戏脚本语言。"
+    io_blurb: "简单而晦涩。"
 
   play:
     choose_your_level: "选择关卡"
@@ -158,7 +158,7 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     trim: "条纹"
     cloud: "云"
     team: "队伍"
-    spell: "魔法球"
+    spell: "法球"
     boots: "鞋子"
     hue: "颜色"
     saturation: "饱和度"
@@ -178,17 +178,17 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     wizard_color: "巫师 衣服 颜色"
     new_password: "新密码"
     new_password_verify: "核实"
-    email_subscriptions: "邮箱验证"
-#    email_subscriptions_none: "No Email Subscriptions."
+    email_subscriptions: "邮箱订阅"
+    email_subscriptions_none: "取消订阅"
     email_announcements: "通知"
     email_announcements_description: "接收关于 CodeCombat 的邮件。"
     email_notifications: "通知"
-#    email_notifications_summary: "Controls for personalized, automatic email notifications related to your CodeCombat activity."
+    email_notifications_summary: "私人定制, 自动通知与您有关的 CodeCombat 活动。"
     email_any_notes: "任何通知"
     email_any_notes_description: "取消接收所有活动提醒邮件"
-#    email_news: "News"
+    email_news: "新消息"
     email_recruit_notes: "工作机会"
-#    email_recruit_notes_description: "If you play really well, we may contact you about getting you a (better) job."
+    email_recruit_notes_description: "如果你干的不错, 我们会联系并提供你更好的工作。"
     contributor_emails: "贡献者通知"
     contribute_prefix: "我们在寻找志同道合的人！请到"
     contribute_page: "贡献页面"
@@ -197,17 +197,17 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     error_saving: "保存时出错"
     saved: "更改已保存"
     password_mismatch: "密码不匹配。"
-#    password_repeat: "Please repeat your password."
+    password_repeat: "请重新键入密码。"
     job_profile: "工作经历"
     job_profile_approved: "你填写的工作经历将由CodeCombat认证. 雇主将看到这些信息，除非你将它设置为不启用状态或者连续四周没有更新."
-    job_profile_explanation: "你好! 填写这些信息, 我们将使用它帮你寻找一份软件开发的工作."
-#    sample_profile: "See a sample profile"
+    job_profile_explanation: "你好! 请填写下列信息, 我们将使用它帮你寻找一份软件开发的工作."
+    sample_profile: "查看示例"
     view_profile: "浏览个人信息"
 
   account_profile:
-#    settings: "Settings"
-#    edit_profile: "Edit Profile"
-#    done_editing: "Done Editing"
+    settings: "设置"
+    edit_profile: "编辑资料"
+    done_editing: "完成编辑"
     profile_for_prefix: "关于他的基本资料："
     profile_for_suffix: ""
 #    featured: "Featured"
@@ -215,8 +215,8 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     looking_for: "寻找"
     last_updated: "最后一次更新："
     contact: "联系"
-#    active: "Looking for interview offers now"
-#    inactive: "Not looking for offers right now"
+    active: "正期待面试offer"
+    inactive: "并不期待面试offer"
 #    complete: "complete"
 #    next: "Next"
 #    next_city: "city?"
@@ -485,31 +485,31 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
 
   multiplayer:
     multiplayer_title: "多人游戏设置"
-#    multiplayer_toggle: "Enable multiplayer"
-#    multiplayer_toggle_description: "Allow others to join your game."
+    multiplayer_toggle: "开启多人模式"
+    multiplayer_toggle_description: "允许其他人加入游戏。"
     multiplayer_link_description: "把这个链接告诉小伙伴们，一起玩吧。"
     multiplayer_hint_label: "提示："
     multiplayer_hint: " 点击全选，然后按 Apple-C（苹果电脑）或 Ctrl-C 复制链接。"
     multiplayer_coming_soon: "多人游戏的更多特性！"
-#    multiplayer_sign_in_leaderboard: "Sign in or create an account and get your solution on the leaderboard."
+    multiplayer_sign_in_leaderboard: "注册并登录账号，就可以将你的成就发布到排行榜上。"
 
-#  keyboard_shortcuts:
-#    keyboard_shortcuts: "Keyboard Shortcuts"
-#    space: "Space"
-#    enter: "Enter"
+  keyboard_shortcuts:
+    keyboard_shortcuts: "热键"
+    space: "空格"
+    enter: "回车"
 #    escape: "Escape"
-#    cast_spell: "Cast current spell."
+    cast_spell: "演示当前咒语"
 #    continue_script: "Continue past current script."
 #    skip_scripts: "Skip past all skippable scripts."
-#    toggle_playback: "Toggle play/pause."
+    toggle_playback: "继续/暂停按钮"
 #    scrub_playback: "Scrub back and forward through time."
 #    single_scrub_playback: "Scrub back and forward through time by a single frame."
 #    scrub_execution: "Scrub through current spell execution."
 #    toggle_debug: "Toggle debug display."
 #    toggle_grid: "Toggle grid overlay."
 #    toggle_pathfinding: "Toggle pathfinding overlay."
-#    beautify: "Beautify your code by standardizing its formatting."
-#    move_wizard: "Move your Wizard around the level."
+    beautify: "利用标准编码格式美化你的代码。"
+    move_wizard: "在关卡中移动你的巫师角色。"
 
   admin:
     av_title: "管理员视图"
@@ -521,43 +521,43 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     av_other_debug_base_url: "Base（用于调试 base.jade）"
     u_title: "用户列表"
     lg_title: "最新的游戏"
-#    clas: "CLAs"
+    clas: "贡献者许可协议"
 
   community:
     main_title: "CodeCombat 社区"
-#    introduction: "Check out the ways you can get involved below and decide what sounds the most fun. We look forward to working with you!"
-#    level_editor_prefix: "Use the CodeCombat"
-#    level_editor_suffix: "to create and edit levels. Users have created levels for their classes, friends, hackathons, students, and siblings. If create a new level sounds intimidating you can start by forking one of ours!"
-#    thang_editor_prefix: "We call units within the game 'thangs'. Use the"
-#    thang_editor_suffix: "to modify the CodeCombat source artwork. Allow units to throw projectiles, alter the direction of an animation, change a unit's hit points, or upload your own vector sprites."
-#    article_editor_prefix: "See a mistake in some of our docs? Want to make some instructions for your own creations? Check out the"
-#    article_editor_suffix: "and help CodeCombat players get the most out of their playtime."
-#    find_us: "Find us on these sites"
-#    contribute_to_the_project: "Contribute to the project"
+    introduction: "看看下面这些你可以参与的项目，如果有你喜欢的就加入进来吧。 我们期待着与您一起工作。"
+    level_editor_prefix: "使用"
+    level_editor_suffix: "来创建和编辑关卡。你可以通过这个工具来给你的同学，朋友，兄弟姐妹们设计谜题，或者用于教学或比赛。如果你觉得直接开始建立一个关卡可能非常困难，那么可以先从一个现成（但尚未完成）的关卡开始做起。"
+    thang_editor_prefix: "我们管游戏中的单位叫 '实体'。 利用"
+    thang_editor_suffix: "来改良 CodeCombat 中的原材料。让游戏中的东西可以被捡起来扔出去，改变游戏动画的指向，调整一些东西的生命值，或上传您自制的素材。"
+    article_editor_prefix: "你在游戏中发现了错误了吗？想要自己设计一些指令吗？来看看我们的"
+    article_editor_suffix: "来帮助玩家从游戏中学到更多的知识。"
+    find_us: "通过这些站点联系我们"
+    contribute_to_the_project: "为项目做贡献"
 
   editor:
     main_title: "CodeCombat 编辑器"
-    main_description: "建立你自己的关卡、 战役、单元和教育内容。我们会提供所有你需要的工具！"
-    article_title: "提示编辑器"
-    article_description: "编写提示，让玩家可以使用编程概念来通过各种关卡和战役。"
-    thang_title: "物体编辑器"
-    thang_description: "创建单元，并定义单元的逻辑、图形和音频。目前只支持导入 Flash 导出的矢量图形。"
+    main_description: "建立你自己的关卡、 战役、单元和新手教程。我们会提供所有你需要的工具！"
+    article_title: "指令编辑器"
+    article_description: "编写指令，让玩家可以使用编程概念来通过各种关卡和战役。"
+    thang_title: "实体编辑器"
+    thang_description: "创建单位，并定义单位的逻辑、图形和音频。目前只支持导入 Flash 导出的矢量图形。"
     level_title: "关卡编辑器"
     level_description: "所有用来创造所有难度的关卡的工具，包括脚本、上传音频和构建自定义逻辑。"
-#    achievement_title: "Achievement Editor"
+    achievement_title: "目标编辑器"
     got_questions: "使用CodeCombat编辑器有问题？"
     contact_us: "联系我们！"
     hipchat_prefix: "你也可以在这里找到我们"
-    hipchat_url: "HipChat 房间。"
+    hipchat_url: "HipChat 聊天室。"
     back: "后退"
     revert: "还原"
     revert_models: "还原模式"
-#    pick_a_terrain: "Pick A Terrain"
-#    small: "Small"
-#    grassy: "Grassy"
+    pick_a_terrain: "选择地形"
+    small: "小的"
+    grassy: "草地"
     fork_title: "派生新版本"
     fork_creating: "正在执行派生..."
-#    randomize: "Randomize"
+    randomize: "随机生成"
     more: "更多"
     wiki: "维基"
     live_chat: "在线聊天"
@@ -591,29 +591,29 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     new_article_title: "创建一个新物品"
     new_thang_title: "创建一个新物品类型"
     new_level_title: "创建一个新关卡"
-#    new_article_title_login: "Log In to Create a New Article"
-#    new_thang_title_login: "Log In to Create a New Thang Type"
-#    new_level_title_login: "Log In to Create a New Level"
-#    new_achievement_title: "Create a New Achievement"
-#    new_achievement_title_login: "Log In to Create a New Achievement"
+    new_article_title_login: "登录以创建新指令"
+    new_thang_title_login: "登录以创建新实体"
+    new_level_title_login: "登录以创建新关卡"
+    new_achievement_title: "创建新目标"
+    new_achievement_title_login: "登录以创建新目标"
     article_search_title: "在这里搜索物品"
     thang_search_title: "在这里搜索物品类型"
     level_search_title: "在这里搜索关卡"
-#    achievement_search_title: "Search Achievements"
+    achievement_search_title: "搜索目标"
     read_only_warning2: "提示：你不能保存任何编辑，因为你没有登陆"
-#    no_achievements: "No achievements have been added for this level yet."
+    no_achievements: "这个关卡还没有被赋予任何目标。"
 #    achievement_query_misc: "Key achievement off of miscellanea"
 #    achievement_query_goals: "Key achievement off of level goals"
-#    level_completion: "Level Completion"
+    level_completion: "关卡完成"
 
   article:
     edit_btn_preview: "预览"
     edit_article_title: "编辑提示"
 
   general:
-    and: "和"
+    and: "与"
     name: "名字"
-#    date: "Date"
+    date: "日期"
     body: "正文"
     version: "版本"
     commit_msg: "提交信息"
@@ -657,7 +657,7 @@ module.exports = nativeDescription: "简体中文", englishDescription: "Chinese
     why_paragraph_4: "如果你一定要对游戏上瘾，那就对这个游戏上瘾，然后成为科技时代的法师吧。"
     why_ending: "再说，这游戏还是免费的。"
     why_ending_url: "开始学习法术！"
-#    george_description: "CEO, business guy, web designer, game designer, and champion of beginning programmers everywhere."
+    george_description: "这里到处都是CEO, 商人, 网站设计师, 游戏设计师和编程新星。"
 #    scott_description: "Programmer extraordinaire, software architect, kitchen wizard, and master of finances. Scott is the reasonable one."
 #    nick_description: "Programming wizard, eccentric motivation mage, and upside-down experimenter. Nick can do anything and chooses to build CodeCombat."
 #    jeremy_description: "Customer support mage, usability tester, and community organizer; you've probably already spoken with Jeremy."
diff --git a/app/models/ThangType.coffee b/app/models/ThangType.coffee
index 24e191d29..8a8d990ea 100644
--- a/app/models/ThangType.coffee
+++ b/app/models/ThangType.coffee
@@ -63,6 +63,7 @@ module.exports = class ThangType extends CocoModel
     options = _.clone options
     options.resolutionFactor ?= SPRITE_RESOLUTION_FACTOR
     options.async ?= false
+    options.thang = null  # Don't hold onto any bad Thang references.
     options
 
   buildSpriteSheet: (options) ->
@@ -276,7 +277,7 @@ module.exports = class ThangType extends CocoModel
       @get('components') or [],
       (compRef) -> compRef.original is LevelComponent.ItemID)
     return itemComponentRef?.config?.slots or []
-    
+
   getFrontFacingStats: ->
     stats = []
     for component in @get('components') or []
@@ -317,4 +318,4 @@ module.exports = class ThangType extends CocoModel
         snippets = config.programmableSnippets
         if snippets.length
           stats.push { name: 'Snippets', value: snippets.join(', ') }
-    stats
\ No newline at end of file
+    stats
diff --git a/app/schemas/models/level.coffee b/app/schemas/models/level.coffee
index d2d4e01aa..2fa229ee1 100644
--- a/app/schemas/models/level.coffee
+++ b/app/schemas/models/level.coffee
@@ -110,8 +110,8 @@ NoteGroupSchema = c.object {title: 'Note Group', description: 'A group of notes
     letterbox: {type: 'boolean', title: 'Letterbox', description: 'Turn letterbox mode on or off. Disables surface and playback controls.'}
 
   goals: c.object {title: 'Goals (Old)', description: 'Deprecated. Goals added here have no effect. Add goals in the level settings instead.'},
-    add: c.array {title: 'Add', description: 'Deprecated. Goals added here have no effect. Add goals in the level settings instead.'}, GoalSchema
-    remove: c.array {title: 'Remove', description: 'Deprecated. Goals removed here have no effect. Adjust goals in the level settings instead.'}, GoalSchema
+    add: c.array {title: 'Add', description: 'Deprecated. Goals added here have no effect. Add goals in the level settings instead.'}, {}
+    remove: c.array {title: 'Remove', description: 'Deprecated. Goals removed here have no effect. Adjust goals in the level settings instead.'}, {}
 
   playback: c.object {title: 'Playback', description: 'Control the playback of the level.'},
     playing: {type: 'boolean', title: 'Set Playing', description: 'Set whether playback is playing or paused.'}
diff --git a/app/schemas/subscriptions/play.coffee b/app/schemas/subscriptions/play.coffee
index 4576450de..f9dce2648 100644
--- a/app/schemas/subscriptions/play.coffee
+++ b/app/schemas/subscriptions/play.coffee
@@ -57,6 +57,48 @@ module.exports =
   'level:victory-hidden':
     {} # TODO schema
 
+  'level:flag-color-selected':
+    type: 'object'
+    additionalProperties: false
+    properties:
+      color:
+        oneOf: [
+          {type: 'null'}
+          {type: 'string', enum: ['green', 'black', 'violet'], description: 'The flag color to place next, or omitted/null if deselected.'}
+        ]
+      pos:
+        type: 'object'
+        additionalProperties: false
+        required: ['x', 'y']
+        properties:
+          x: {type: 'number'}
+          y: {type: 'number'}
+
+  'level:flag-updated':
+    type: 'object'
+    additionalProperties: false
+    required: ['player', 'color', 'time', 'active']
+    properties:
+      player:
+        type: 'string'
+      team:
+        type: 'string'
+      color:
+        type: 'string'
+        enum: ['green', 'black', 'violet']
+      time:
+        type: 'number'
+        minimum: 0
+      active:
+        type: 'boolean'
+      pos:
+        type: 'object'
+        additionalProperties: false
+        required: ['x', 'y']
+        properties:
+          x: {type: 'number'}
+          y: {type: 'number'}
+
   'next-game-pressed':
     {} # TODO schema
 
@@ -105,6 +147,14 @@ module.exports =
   'playback:manually-scrubbed':
     {} # TODO schema
 
+  'playback:real-time-playback-started':
+    type: 'object'
+    additionalProperties: false
+
+  'playback:real-time-playback-ended':
+    type: 'object'
+    additionalProperties: false
+
   'change:editor-config':
     {} # TODO schema
 
diff --git a/app/schemas/subscriptions/surface.coffee b/app/schemas/subscriptions/surface.coffee
index 0c7413248..ee3b98458 100644
--- a/app/schemas/subscriptions/surface.coffee
+++ b/app/schemas/subscriptions/surface.coffee
@@ -94,3 +94,15 @@ module.exports =  # /app/lib/surface
 
   'echo-all-wizard-sprites':
     {} # TODO schema
+
+  'surface:flag-appeared':
+    type: 'object'
+    additionalProperties: false
+    required: ['sprite']
+    properties:
+      sprite:
+        type: 'object'
+
+  'surface:remove-selected-flag':
+    type: 'object'
+    additionalProperties: false
diff --git a/app/schemas/subscriptions/tome.coffee b/app/schemas/subscriptions/tome.coffee
index 42af94472..a582156e1 100644
--- a/app/schemas/subscriptions/tome.coffee
+++ b/app/schemas/subscriptions/tome.coffee
@@ -11,10 +11,11 @@ module.exports =
         type: "object"
       preload:
         type: "boolean"
+      realTime:
+        type: "boolean"
     required: []
     additionalProperties: false
 
-  # TODO do we really need both 'cast-spell' and 'cast-spells'?
   "tome:cast-spells":
     title: "Cast Spells"
     $schema: "http://json-schema.org/draft-04/schema#"
@@ -25,6 +26,8 @@ module.exports =
         type: "object"
       preload:
         type: "boolean"
+      realTime:
+        type: "boolean"
     required: []
     additionalProperties: false
 
@@ -33,7 +36,9 @@ module.exports =
     $schema: "http://json-schema.org/draft-04/schema#"
     description: "Published when you wish to manually recast all spells"
     type: "object"
-    properties: {}
+    properties:
+      realTime:
+        type: "boolean"
     required: []
     additionalProperties: false
 
diff --git a/app/schemas/subscriptions/world.coffee b/app/schemas/subscriptions/world.coffee
index 9cb7487f0..0eb748c5e 100644
--- a/app/schemas/subscriptions/world.coffee
+++ b/app/schemas/subscriptions/world.coffee
@@ -11,5 +11,8 @@ module.exports =
   'god:new-world-created':
     {} # TODO schema
 
+  'god:streaming-world-updated':
+    {} # TODO schema
+
   'god:world-load-progress-changed':
     {} # TODO schema
diff --git a/app/styles/base.sass b/app/styles/base.sass
index 332aaa624..a00d037ee 100644
--- a/app/styles/base.sass
+++ b/app/styles/base.sass
@@ -225,10 +225,6 @@ table.table
 .ui-slider-handle
   border: 1px solid black !important
 
-.flag-cursor
-  cursor: crosshair
-
-
 // Fonts
 
 .header-font
diff --git a/app/styles/play/level.sass b/app/styles/play/level.sass
index b0d52ea6f..d2fa31a62 100644
--- a/app/styles/play/level.sass
+++ b/app/styles/play/level.sass
@@ -10,6 +10,34 @@ body.is-playing
   margin: 0 auto
   @include user-select(none)
 
+  &.real-time
+    // Hmm, somehow the #page-container is cutting us off by ~17px on the right, looks a bit off.
+
+    #canvas-wrapper
+      width: 100%
+      canvas#surface
+        margin: 0 auto
+    #control-bar-view
+      width: 100%
+    #playback-view
+      $flags-width: 200px
+      width: 90%
+      width: -webkit-calc(100% - $flags-width)
+      width: calc(100% - $flags-width)
+      left: $flags-width
+    #code-area, #thang-hud, #goals-view
+      display: none
+      visibility: hidden
+    #gold-view
+      right: 1%
+    #control-bar-view .title
+      left: 20%
+      width: 60%
+      text-align: center
+
+    .level-content
+      margin: 0px auto
+
   .level-content
     position: relative
 
@@ -17,13 +45,17 @@ body.is-playing
     width: 55%
     position: relative
     overflow: hidden
+    @include transition(0.5s ease-out)
     
   canvas#surface
     background-color: #333
-    width: 100%
     display: block
     z-index: 1
-    
+    @include transition(0.5s ease-out)
+
+    &.flag-color-selected
+      cursor: crosshair
+
   min-width: 1024px
   position: relative
 
diff --git a/app/styles/play/level/gold.sass b/app/styles/play/level/gold.sass
index c1efa04bb..283f5b7f9 100644
--- a/app/styles/play/level/gold.sass
+++ b/app/styles/play/level/gold.sass
@@ -6,9 +6,8 @@
   position: absolute
   right: 46%
   top: 42px
-  user-select: none
-  -webkit-user-select: none
   @include transition(box-shadow .2s linear)
+  @include user-select(none)
   padding: 4px
   background: transparent url(/images/level/gold_background.png) no-repeat
   background-size: 100% 100%
diff --git a/app/styles/play/level/level-flags-view.sass b/app/styles/play/level/level-flags-view.sass
new file mode 100644
index 000000000..5ee49c10d
--- /dev/null
+++ b/app/styles/play/level/level-flags-view.sass
@@ -0,0 +1,53 @@
+@import "app/styles/mixins"
+@import "app/styles/bootstrap/mixins"
+
+#level-flags-view
+  display: none
+  position: absolute
+  bottom: 0
+  left: 0
+  width: 200px
+  // Width must match level.sass playback offset
+  z-index: 1
+  @include transition(box-shadow .2s linear)
+  @include user-select(none)
+  padding: 4px
+  background: transparent url(/images/level/gold_background.png) no-repeat
+  background-size: 100% 100%
+  border-radius: 4px
+
+  &:hover
+    box-shadow: 2px 2px 2px black
+
+  .flag-button
+    margin: 3px
+    font-size: 14px
+    position: relative
+    padding: 2px 15px 18px 15px
+    margin-left: 5px
+
+    .glyphicon
+      font-size: 24px
+
+    .flag-shortcut
+      text-decoration: underline
+
+    &.green-flag
+      .glyphicon, .flag-shortcut
+        color: hsl(120, 50%, 50%)
+    &.black-flag
+      .glyphicon, .flag-shortcut
+        color: hsl(0, 0%, 25%)
+    &.violet-flag
+      .glyphicon, .flag-shortcut
+        color: hsl(300, 50%, 50%)
+
+    .flag-caption
+      position: absolute
+      background-color: rgba(0, 0, 0, 0.1)
+      color: black
+      bottom: 0
+      left: 0
+      width: 100%
+      border-bottom-right-radius: 6px
+      border-bottom-left-radius: 6px
diff --git a/app/styles/play/level/playback.sass b/app/styles/play/level/playback.sass
index ebeff9846..b67e8ee28 100644
--- a/app/styles/play/level/playback.sass
+++ b/app/styles/play/level/playback.sass
@@ -97,6 +97,8 @@
       background-image: none
       border-radius: 0
       border: 0
+      // Can't do this transition because handle then jitters, but would be good for streaming.
+      //@include transition(width .2s linear)
 
       &.disabled
         cursor: default
diff --git a/app/styles/play/level/tome/cast_button.sass b/app/styles/play/level/tome/cast_button.sass
index 87afdad55..38e71cc3d 100644
--- a/app/styles/play/level/tome/cast_button.sass
+++ b/app/styles/play/level/tome/cast_button.sass
@@ -82,7 +82,9 @@
       height: 40px
 
     .cast-button
-      width: 100%
+      width: 80%
+      width: -webkit-calc(100% - 40px)
+      width: calc(100% - 40px)
       border-top-left-radius: 6px
       border-bottom-left-radius: 6px
 
@@ -92,3 +94,8 @@
         font-size: 14px
       @media screen and (max-width: 1024px)
         font-size: 12px
+
+    .cast-real-time-button
+      width: 20%
+      width: -webkit-calc(40px)
+      width: calc(40px)
diff --git a/app/styles/play/spectate.sass b/app/styles/play/spectate.sass
index 43d44e320..746a6589f 100644
--- a/app/styles/play/spectate.sass
+++ b/app/styles/play/spectate.sass
@@ -19,11 +19,11 @@
     .title
       position: absolute
       display: inline-block
-      margin-left: 50%
-      right: 0
       color: #BEBEBE
       line-height: 15px
-      left: 0
+      left: 20%
+      width: 60%
+      text-align: center
 
   max-width: 1920px
   margin: 0 auto
diff --git a/app/templates/play/level.jade b/app/templates/play/level.jade
index a4d9d4fd9..ac9b335f9 100644
--- a/app/templates/play/level.jade
+++ b/app/templates/play/level.jade
@@ -13,6 +13,8 @@
     #canvas-top-gradient.gradient
     #goals-view.secret
   
+  #level-flags-view.secret
+
   #gold-view.secret.expanded
 
   #level-chat-view
diff --git a/app/templates/play/level/level-flags-view.jade b/app/templates/play/level/level-flags-view.jade
new file mode 100644
index 000000000..11f3d0f5e
--- /dev/null
+++ b/app/templates/play/level/level-flags-view.jade
@@ -0,0 +1,15 @@
+button.flag-button.btn.btn-lg.green-flag(title="G: Place a green flag")
+  span.glyphicon.glyphicon-flag
+  span.flag-caption
+    span.flag-shortcut G
+    | reen
+button.flag-button.btn.btn-lg.black-flag(title="B: Place a black flag")
+  span.glyphicon.glyphicon-flag
+  span.flag-caption
+    span.flag-shortcut B
+    | lack
+button.flag-button.btn.btn-lg.violet-flag(title="V: Place a violet flag")
+  span.glyphicon.glyphicon-flag
+  span.flag-caption
+    span.flag-shortcut V
+    | iolet
diff --git a/app/templates/play/level/modal/keyboard_shortcuts.jade b/app/templates/play/level/modal/keyboard_shortcuts.jade
index a920a6f73..41b67c8f8 100644
--- a/app/templates/play/level/modal/keyboard_shortcuts.jade
+++ b/app/templates/play/level/modal/keyboard_shortcuts.jade
@@ -8,6 +8,10 @@ block modal-body-content
     dt(title="Shift+" + enter)
       code ⇧+#{enter}
     dd(data-i18n="keyboard_shortcuts.cast_spell") Cast current spell.
+  dl.dl-horizontal
+    dt(title=ctrlName + "+Shift+" + enter)
+      code #{ctrl}+⇧+#{enter}
+    dd(data-i18n="keyboard_shortcuts.run_real_time") Run in real time.
   dl.dl-horizontal
     dt(title="Shift+" + space)
       code ⇧+#{space}
diff --git a/app/templates/play/level/tome/cast_button.jade b/app/templates/play/level/tome/cast_button.jade
index cbaf3079b..3f3d6669f 100644
--- a/app/templates/play/level/tome/cast_button.jade
+++ b/app/templates/play/level/tome/cast_button.jade
@@ -1,3 +1,5 @@
-div.btn-group.btn-group-lg.cast-button-group.dropup
+div.btn-group.btn-group-lg.cast-button-group
   .button-progress-overlay
-  button.btn.btn-inverse.banner.cast-button(title=castShortcutVerbose + ": Cast current spell", data-i18n="play_level.tome_cast_button_cast") Spell Cast
+  button.btn.btn-inverse.banner.cast-button(title=castVerbose, data-i18n="play_level.tome_cast_button_cast") Spell Cast
+  button.btn.btn-inverse.banner.cast-real-time-button(title=castRealTimeVerbose)
+    i.glyphicon.glyphicon-play
\ No newline at end of file
diff --git a/app/views/kinds/SearchView.coffee b/app/views/kinds/SearchView.coffee
index 1e41c8ead..7d5fa8b0f 100644
--- a/app/views/kinds/SearchView.coffee
+++ b/app/views/kinds/SearchView.coffee
@@ -83,5 +83,5 @@ module.exports = class SearchView extends RootView
 
   newModel: (e) ->
     modal = new NewModelModal model: @model, modelLabel: @modelLabel
-    modal.once 'success', @onNewModelSaved
+    modal.once 'model-created', @onNewModelSaved
     @openModalView modal
diff --git a/app/views/play/SpectateView.coffee b/app/views/play/SpectateView.coffee
index bda2cce7e..8c23d779d 100644
--- a/app/views/play/SpectateView.coffee
+++ b/app/views/play/SpectateView.coffee
@@ -55,6 +55,7 @@ module.exports = class SpectateLevelView extends RootView
     'surface:world-set-up': 'onSurfaceSetUpNewWorld'
     'level:set-team': 'setTeam'
     'god:new-world-created': 'loadSoundsForWorld'
+    'god:streaming-world-updated': 'loadSoundsForWorld'
     'next-game-pressed': 'onNextGamePressed'
     'level:started': 'onLevelStarted'
     'level:loading-view-unveiled': 'onLoadingViewUnveiled'
diff --git a/app/views/play/ladder/LadderTabView.coffee b/app/views/play/ladder/LadderTabView.coffee
index 1780fa057..27a43c4b6 100644
--- a/app/views/play/ladder/LadderTabView.coffee
+++ b/app/views/play/ladder/LadderTabView.coffee
@@ -197,8 +197,9 @@ module.exports = class LadderTabView extends CocoView
 
     formatCount = d3.format(',.0')
 
-    x = d3.scale.linear().domain([-3000, 6000]).range([0, width])
-
+    minX = Math.floor(Math.min(histogramData...) / 1000) * 1000
+    maxX = Math.ceil(Math.max(histogramData...) / 1000) * 1000
+    x = d3.scale.linear().domain([minX, maxX]).range([0, width])
     data = d3.layout.histogram().bins(x.ticks(20))(histogramData)
     y = d3.scale.linear().domain([0, d3.max(data, (d) -> d.y)]).range([height, 10])
 
diff --git a/app/views/play/level/LevelFlagsView.coffee b/app/views/play/level/LevelFlagsView.coffee
new file mode 100644
index 000000000..25bc54293
--- /dev/null
+++ b/app/views/play/level/LevelFlagsView.coffee
@@ -0,0 +1,74 @@
+CocoView = require 'views/kinds/CocoView'
+template = require 'templates/play/level/level-flags-view'
+{me} = require 'lib/auth'
+
+module.exports = class LevelFlagsView extends CocoView
+  id: 'level-flags-view'
+  template: template
+
+  subscriptions:
+    'playback:real-time-playback-started': 'onRealTimePlaybackStarted'
+    'playback:real-time-playback-ended': 'onRealTimePlaybackEnded'
+    'surface:stage-mouse-down': 'onStageMouseDown'
+    'god:new-world-created': 'onNewWorld'
+    'god:streaming-world-updated': 'onNewWorld'
+    'surface:remove-flag': 'onRemoveFlag'
+
+  events:
+    'click .green-flag': -> @onFlagSelected color: 'green', source: 'button'
+    'click .black-flag': -> @onFlagSelected color: 'black', source: 'button'
+    'click .violet-flag': -> @onFlagSelected color: 'violet', source: 'button'
+
+  shortcuts:
+    'g': -> @onFlagSelected color: 'green', source: 'shortcut'
+    'b': -> @onFlagSelected color: 'black', source: 'shortcut'
+    'v': -> @onFlagSelected color: 'violet', source: 'shortcut'
+    'esc': -> @onFlagSelected color: null, source: 'shortcut'
+    'delete, del, backspace': 'onDeletePressed'
+
+  constructor: (options) ->
+    super options
+    @world = options.world
+
+  onRealTimePlaybackStarted: (e) ->
+    @realTime = true
+    @$el.show()
+    @flags = {}
+    @flagHistory = []
+
+  onRealTimePlaybackEnded: (e) ->
+    @onFlagSelected color: null
+    @realTime = false
+    @$el.hide()
+
+  onFlagSelected: (e) ->
+    return unless @realTime
+    color = if e.color is @flagColor then null else e.color
+    @flagColor = color
+    Backbone.Mediator.publish 'level:flag-color-selected', color: color
+    @$el.find('.flag-button').removeClass('active')
+    @$el.find(".#{color}-flag").addClass('active') if color
+
+  onStageMouseDown: (e) ->
+    return unless @flagColor and @realTime
+    pos = x: e.worldPos.x, y: e.worldPos.y
+    flag = player: me.id, team: me.team, color: @flagColor, pos: pos, time: @world.dt * @world.frames.length, active: true
+    @flags[@flagColor] = flag
+    @flagHistory.push flag
+    Backbone.Mediator.publish 'level:flag-updated', flag
+    #console.log 'trying to place flag at', @world.age, 'and think it will happen by', flag.time
+
+  onDeletePressed: (e) ->
+    return unless @realTime
+    Backbone.Mediator.publish 'surface:remove-selected-flag', {}
+
+  onRemoveFlag: (e) ->
+    delete @flags[e.color]
+    flag = player: me.id, team: me.team, color: e.color, time: @world.dt * @world.frames.length, active: false
+    @flagHistory.push flag
+    Backbone.Mediator.publish 'level:flag-updated', flag
+    #console.log e.color, 'deleted at time', flag.time
+
+  onNewWorld: (event) ->
+    return unless event.world.name is @world.name
+    @world = @options.world = event.world
diff --git a/app/views/play/level/LevelHUDView.coffee b/app/views/play/level/LevelHUDView.coffee
index 6daa1d8d9..a273712b2 100644
--- a/app/views/play/level/LevelHUDView.coffee
+++ b/app/views/play/level/LevelHUDView.coffee
@@ -70,6 +70,8 @@ module.exports = class LevelHUDView extends CocoView
     @thang = e.world.thangMap[@thang.id] if @thang
     if hadThang and not @thang
       @setThang null, null
+    else if @thang
+      @createActions()  # Make sure it updates its actions.
 
   setThang: (thang, thangType) ->
     unless @speaker
diff --git a/app/views/play/level/LevelPlaybackView.coffee b/app/views/play/level/LevelPlaybackView.coffee
index eb619ce06..63fdc9379 100644
--- a/app/views/play/level/LevelPlaybackView.coffee
+++ b/app/views/play/level/LevelPlaybackView.coffee
@@ -22,8 +22,10 @@ module.exports = class LevelPlaybackView extends CocoView
     'level-toggle-grid': 'onToggleGrid'
     'surface:frame-changed': 'onFrameChanged'
     'god:new-world-created': 'onNewWorld'
+    'god:streaming-world-updated': 'onNewWorld'
     'level-set-letterbox': 'onSetLetterbox'
-    'tome:cast-spells': 'onCastSpells'
+    'tome:cast-spells': 'onTomeCast'
+    'playback:real-time-playback-ended': 'onRealTimePlaybackEnded'
 
   events:
     'click #debug-toggle': 'onToggleDebug'
@@ -36,7 +38,7 @@ module.exports = class LevelPlaybackView extends CocoView
     'click #zoom-out-button': -> Backbone.Mediator.publish('camera-zoom-out') unless @shouldIgnore()
     'click #volume-button': 'onToggleVolume'
     'click #play-button': 'onTogglePlay'
-    'click': -> Backbone.Mediator.publish 'tome:focus-editor'
+    'click': -> Backbone.Mediator.publish 'tome:focus-editor' unless @realTime
     'mouseenter #timeProgress': 'onProgressEnter'
     'mouseleave #timeProgress': 'onProgressLeave'
     'mousemove #timeProgress': 'onProgressHover'
@@ -114,6 +116,15 @@ module.exports = class LevelPlaybackView extends CocoView
     ua = navigator.userAgent.toLowerCase()
     if /safari/.test(ua) and not /chrome/.test(ua)
       @$el.find('.toggle-fullscreen').hide()
+    @timePopup ?= new HoverPopup
+    t = $.i18n.t
+    @second = t 'units.second'
+    @seconds = t 'units.seconds'
+    @minute = t 'units.minute'
+    @minutes = t 'units.minutes'
+    @goto = t 'play_level.time_goto'
+    @current = t 'play_level.time_current'
+    @total = t 'play_level.time_total'
 
   updatePopupContent: ->
     @timePopup?.updateContent "<h2>#{@timeToString @newTime}</h2>#{@formatTime(@current, @currentTime)}<br/>#{@formatTime(@total, @totalTime)}"
@@ -142,32 +153,34 @@ module.exports = class LevelPlaybackView extends CocoView
     @$el.find('#music-button').toggleClass('music-on', me.get('music'))
 
   onSetLetterbox: (e) ->
-    buttons = @$el.find '#play-button, .scrubber-handle'
-    buttons.css 'visibility', if e.on then 'hidden' else 'visible'
+    return if @realTime
+    @togglePlaybackControls !e.on
     @disabled = e.on
 
+  togglePlaybackControls: (to) ->
+    buttons = @$el.find '#play-button, .scrubber-handle'
+    buttons.css 'visibility', if to then 'visible' else 'hidden'
+
+  onTomeCast: (e) ->
+    return unless e.realTime
+    @realTime = true
+    @togglePlaybackControls false
+    Backbone.Mediator.publish 'playback:real-time-playback-started', {}
+
   onWindowResize: (s...) =>
     @barWidth = $('.progress', @$el).width()
 
   onNewWorld: (e) ->
-    @totalTime = e.world.totalFrames / e.world.frameRate
-    pct = parseInt(100 * e.world.totalFrames / e.world.maxTotalFrames) + '%'
+    @updateBarWidth e.world.frames.length, e.world.maxTotalFrames, e.world.dt
+
+  updateBarWidth: (loadedFrameCount, maxTotalFrames, dt) ->
+    @totalTime = loadedFrameCount * dt
+    pct = parseInt(100 * loadedFrameCount / maxTotalFrames) + '%'
     @barWidth = $('.progress', @$el).css('width', pct).show().width()
-    @casting = false
     $('.scrubber .progress', @$el).slider('enable', true)
     @newTime = 0
     @currentTime = 0
-
-    @timePopup ?= new HoverPopup
-
-    t = $.i18n.t
-    @second = t 'units.second'
-    @seconds = t 'units.seconds'
-    @minute = t 'units.minute'
-    @minutes = t 'units.minutes'
-    @goto = t 'play_level.time_goto'
-    @current = t 'play_level.time_current'
-    @total = t 'play_level.time_total'
+    @lastLoadedFrameCount = loadedFrameCount
 
   onToggleDebug: ->
     return if @shouldIgnore()
@@ -188,11 +201,6 @@ module.exports = class LevelPlaybackView extends CocoView
   onViewKeyboardShortcuts: ->
     @openModalView new KeyboardShortcutsModal()
 
-  onCastSpells: (e) ->
-    return if e.preload
-    @casting = true
-    @$progressScrubber.slider('disable', true)
-
   onDisableControls: (e) ->
     if not e.controls or 'playback' in e.controls
       @disabled = true
@@ -205,6 +213,7 @@ module.exports = class LevelPlaybackView extends CocoView
     $('#volume-button', @$el).removeClass('disabled')
 
   onEnableControls: (e) ->
+    return if @realTime
     if not e.controls or 'playback' in e.controls
       @disabled = false
       $('button', @$el).removeClass('disabled')
@@ -255,7 +264,7 @@ module.exports = class LevelPlaybackView extends CocoView
       # @currentTime = @totalTime if Math.abs(@totalTime - @currentTime) < 0.04
       @updatePopupContent() if @timePopup?.shown
 
-      @updateProgress(e.progress)
+      @updateProgress(e.progress, e.world)
       @updatePlayButton(e.progress)
     @lastProgress = e.progress
 
@@ -277,16 +286,28 @@ module.exports = class LevelPlaybackView extends CocoView
     if @timePopup and Math.abs(@currentTime - @newTime) < 1 and not @timePopup.shown
       @timePopup.show()
 
-  updateProgress: (progress) ->
-    $('.scrubber .progress-bar', @$el).css('width', "#{progress*100}%")
+  updateProgress: (progress, world) ->
+    if world.frames.length isnt @lastLoadedFrameCount
+      @updateBarWidth world.frames.length, world.maxTotalFrames, world.dt
+    wasLoaded = @worldCompletelyLoaded
+    @worldCompletelyLoaded = world.frames.length is world.totalFrames
+    if @realTime and @worldCompletelyLoaded and not wasLoaded
+      Backbone.Mediator.publish 'playback:real-time-playback-ended', {}
+    $('.scrubber .progress-bar', @$el).css('width', "#{progress * 100}%")
 
   updatePlayButton: (progress) ->
-    if progress >= 0.99 and @lastProgress < 0.99
+    if @worldCompletelyLoaded and progress >= 0.99 and @lastProgress < 0.99
       $('#play-button').removeClass('playing').removeClass('paused').addClass('ended')
+      Backbone.Mediator.publish 'playback:real-time-playback-ended', {} if @realTime
     if progress < 0.99 and @lastProgress >= 0.99
       b = $('#play-button').removeClass('ended')
       if @playing then b.addClass('playing') else b.addClass('paused')
 
+  onRealTimePlaybackEnded: (e) ->
+    return unless @realTime
+    @realTime = false
+    @togglePlaybackControls true
+
   onSetDebug: (e) ->
     flag = $('#debug-toggle i.icon-ok')
     flag.toggleClass 'invisible', not e.debug
@@ -299,20 +320,22 @@ module.exports = class LevelPlaybackView extends CocoView
 
   hookUpScrubber: ->
     @sliderIncrements = 500  # max slider width before we skip pixels
-    @clickingSlider = false  # whether the mouse has been pressed down without moving
     @$progressScrubber.slider(
       max: @sliderIncrements
       animate: 'slow'
       slide: (event, ui) =>
+        return if @shouldIgnore()
         @scrubTo ui.value / @sliderIncrements
         @slideCount += 1
 
       start: (event, ui) =>
+        return if @shouldIgnore()
         @slideCount = 0
         @wasPlaying = @playing
         Backbone.Mediator.publish 'level-set-playing', {playing: false}
 
       stop: (event, ui) =>
+        return if @shouldIgnore()
         @actualProgress = ui.value / @sliderIncrements
         Backbone.Mediator.publish 'playback:manually-scrubbed', ratio: @actualProgress
         Backbone.Mediator.publish 'level-set-playing', {playing: @wasPlaying}
@@ -329,7 +352,7 @@ module.exports = class LevelPlaybackView extends CocoView
     return if @shouldIgnore()
     Backbone.Mediator.publish 'level-set-time', ratio: ratio, scrubDuration: duration
 
-  shouldIgnore: -> return @disabled or @casting or false
+  shouldIgnore: -> return @disabled or @realTime
 
   onTogglePlay: (e) ->
     e?.preventDefault()
diff --git a/app/views/play/level/PlayLevelView.coffee b/app/views/play/level/PlayLevelView.coffee
index 604625705..dde56b11e 100644
--- a/app/views/play/level/PlayLevelView.coffee
+++ b/app/views/play/level/PlayLevelView.coffee
@@ -29,6 +29,7 @@ HUDView = require './LevelHUDView'
 ControlBarView = require './ControlBarView'
 LevelPlaybackView = require './LevelPlaybackView'
 GoalsView = require './LevelGoalsView'
+LevelFlagsView = require './LevelFlagsView'
 GoldView = require './LevelGoldView'
 VictoryModal = require './modal/VictoryModal'
 InfiniteLoopModal = require './modal/InfiniteLoopModal'
@@ -53,6 +54,7 @@ module.exports = class PlayLevelView extends RootView
     'level-disable-controls': 'onDisableControls'
     'level-enable-controls': 'onEnableControls'
     'god:new-world-created': 'onNewWorld'
+    'god:streaming-world-updated': 'onNewWorld'
     'god:infinite-loop': 'onInfiniteLoop'
     'level-reload-from-data': 'onLevelReloadFromData'
     'level-reload-thang-type': 'onLevelReloadThangType'
@@ -63,6 +65,8 @@ module.exports = class PlayLevelView extends RootView
     'level:set-team': 'setTeam'
     'level:started': 'onLevelStarted'
     'level:loading-view-unveiled': 'onLoadingViewUnveiled'
+    'playback:real-time-playback-started': 'onRealTimePlaybackStarted'
+    'playback:real-time-playback-ended': 'onRealTimePlaybackEnded'
 
   events:
     'click #level-done-button': 'onDonePressed'
@@ -232,6 +236,7 @@ module.exports = class PlayLevelView extends RootView
     @insertSubView @tome = new TomeView levelID: @levelID, session: @session, otherSession: @otherSession, thangs: @world.thangs, supermodel: @supermodel
     @insertSubView new LevelPlaybackView session: @session
     @insertSubView new GoalsView {}
+    @insertSubView new LevelFlagsView world: @world
     @insertSubView new GoldView {}
     @insertSubView new HUDView {}
     @insertSubView new ChatView levelID: @levelID, sessionID: @session.id, session: @session
@@ -507,11 +512,25 @@ module.exports = class PlayLevelView extends RootView
     @world = e.world
     @world.scripts = scripts
     thangTypes = @supermodel.getModels(ThangType)
-    for [spriteName, message] in @world.thangDialogueSounds()
+    startFrame = @lastWorldFramesLoaded ? 0
+    if @world.frames.length is @world.totalFrames  # Finished loading
+      @lastWorldFramesLoaded = 0
+    else
+      @lastWorldFramesLoaded = @world.frames.length
+    for [spriteName, message] in @world.thangDialogueSounds startFrame
       continue unless thangType = _.find thangTypes, (m) -> m.get('name') is spriteName
       continue unless sound = AudioPlayer.soundForDialogue message, thangType.get('soundTriggers')
       AudioPlayer.preloadSoundReference sound
 
+  # Real-time playback
+  onRealTimePlaybackStarted: (e) ->
+    @$el.addClass('real-time').focus()
+    @onWindowResize()
+
+  onRealTimePlaybackEnded: (e) ->
+    @$el.removeClass 'real-time'
+    @onWindowResize()
+
   destroy: ->
     @levelLoader?.destroy()
     @surface?.destroy()
diff --git a/app/views/play/level/ThangAvatarView.coffee b/app/views/play/level/ThangAvatarView.coffee
index 90ea72be1..3c65bc848 100644
--- a/app/views/play/level/ThangAvatarView.coffee
+++ b/app/views/play/level/ThangAvatarView.coffee
@@ -70,7 +70,7 @@ module.exports = class ThangAvatarView extends CocoView
     @setProblems myProblems.length, worstLevel
 
   onNewWorld: (e) ->
-    @options.thang = @thang = e.world.thangMap[@thang.id] if @thang
+    @options.thang = @thang = e.world.thangMap[@thang.id] if @thang and e.world.thangMap[@thang.id]
 
   destroy: ->
     super()
diff --git a/app/views/play/level/tome/CastButtonView.coffee b/app/views/play/level/tome/CastButtonView.coffee
index fe82e4c28..f28500fdf 100644
--- a/app/views/play/level/tome/CastButtonView.coffee
+++ b/app/views/play/level/tome/CastButtonView.coffee
@@ -8,7 +8,7 @@ module.exports = class CastButtonView extends CocoView
 
   events:
     'click .cast-button': 'onCastButtonClick'
-    'click .autocast-delays a': 'onCastOptionsClick'
+    'click .cast-real-time-button': 'onCastRealTimeButtonClick'
 
   subscriptions:
     'tome:spell-changed': 'onSpellChanged'
@@ -21,11 +21,15 @@ module.exports = class CastButtonView extends CocoView
     @spells = options.spells
     @levelID = options.levelID
     @castShortcut = '⇧↵'
-    @castShortcutVerbose = 'Shift+Enter'
 
   getRenderData: (context={}) ->
     context = super context
-    context.castShortcutVerbose = @castShortcutVerbose
+    shift = $.i18n.t 'keyboard_shortcuts.shift'
+    enter = $.i18n.t 'keyboard_shortcuts.enter'
+    castShortcutVerbose = "#{shift}+#{enter}"
+    castRealTimeShortcutVerbose = (if @isMac() then 'Cmd' else 'Ctrl') + '+' + castShortcutVerbose
+    context.castVerbose = castShortcutVerbose + ': ' + $.i18n.t('keyboard_shortcuts.cast_spell')
+    context.castRealTimeVerbose = castRealTimeShortcutVerbose + ': ' + $.i18n.t('keyboard_shortcuts.run_real_time')
     context
 
   afterRender: ->
@@ -34,9 +38,7 @@ module.exports = class CastButtonView extends CocoView
     @castButtonGroup = $('.cast-button-group', @$el)
     @castOptions = $('.autocast-delays', @$el)
     delay = me.get('autocastDelay')
-    delay ?= 5000
-    unless @levelID in ['rescue-mission', 'grab-the-mushroom', 'drink-me', 'its-a-trap', 'break-the-prison', 'taunt', 'cowardly-taunt', 'commanding-followers', 'mobile-artillery']
-      delay = 90019001
+    delay ?= 90019001
     @setAutocastDelay delay
 
   attachTo: (spellView) ->
@@ -45,6 +47,9 @@ module.exports = class CastButtonView extends CocoView
   onCastButtonClick: (e) ->
     Backbone.Mediator.publish 'tome:manual-cast', {}
 
+  onCastRealTimeButtonClick: (e) ->
+    Backbone.Mediator.publish 'tome:manual-cast', {realTime: true}
+
   onCastOptionsClick: (e) =>
     Backbone.Mediator.publish 'tome:focus-editor'
     @castButtonGroup.removeClass 'open'
@@ -98,6 +103,6 @@ module.exports = class CastButtonView extends CocoView
     @autocastDelay = delay = parseInt delay
     me.set('autocastDelay', delay)
     me.patch()
-    spell.view.setAutocastDelay delay for spellKey, spell of @spells
+    spell.view?.setAutocastDelay delay for spellKey, spell of @spells
     @castOptions.find('a').each ->
       $(@).toggleClass('selected', parseInt($(@).attr('data-delay')) is delay)
diff --git a/app/views/play/level/tome/Spell.coffee b/app/views/play/level/tome/Spell.coffee
index af6628eac..ff2dc39e6 100644
--- a/app/views/play/level/tome/Spell.coffee
+++ b/app/views/play/level/tome/Spell.coffee
@@ -40,16 +40,17 @@ module.exports = class Spell
     if @permissions.readwrite.length and sessionSource = @session.getSourceFor(@spellKey)
       @source = sessionSource
     @thangs = {}
-    @view = new SpellView {spell: @, session: @session, worker: @worker}
-    @view.render()  # Get it ready and code loaded in advance
-    @tabView = new SpellListTabEntryView spell: @, supermodel: @supermodel, language: @language
-    @tabView.render()
+    if @canRead()  # We can avoid creating these views if we'll never use them.
+      @view = new SpellView {spell: @, session: @session, worker: @worker}
+      @view.render()  # Get it ready and code loaded in advance
+      @tabView = new SpellListTabEntryView spell: @, supermodel: @supermodel, language: @language
+      @tabView.render()
     @team = @permissions.readwrite[0] ? 'common'
     Backbone.Mediator.publish 'tome:spell-created', spell: @
 
   destroy: ->
-    @view.destroy()
-    @tabView.destroy()
+    @view?.destroy()
+    @tabView?.destroy()
     @thangs = null
     @worker = null
 
@@ -72,7 +73,7 @@ module.exports = class Spell
     (team ? me.team) in @permissions.readwrite
 
   getSource: ->
-    @view.getSource()
+    @view?.getSource() ? @source
 
   transpile: (source) ->
     if source
diff --git a/app/views/play/level/tome/SpellView.coffee b/app/views/play/level/tome/SpellView.coffee
index 024b60ee0..80c86296f 100644
--- a/app/views/play/level/tome/SpellView.coffee
+++ b/app/views/play/level/tome/SpellView.coffee
@@ -114,6 +114,10 @@ module.exports = class SpellView extends CocoView
       name: 'run-code'
       bindKey: {win: 'Shift-Enter|Ctrl-Enter', mac: 'Shift-Enter|Command-Enter|Ctrl-Enter'}
       exec: -> Backbone.Mediator.publish 'tome:manual-cast', {}
+    addCommand
+      name: 'run-code-real-time'
+      bindKey: {win: 'Ctrl-Shift-Enter', mac: 'Command-Shift-Enter|Ctrl-Shift-Enter'}
+      exec: -> Backbone.Mediator.publish 'tome:manual-cast', {realTime: true}
     addCommand
       name: 'no-op'
       bindKey: {win: 'Ctrl-S', mac: 'Command-S|Ctrl-S'}
@@ -128,10 +132,10 @@ module.exports = class SpellView extends CocoView
       # passEvent: true  # https://github.com/ajaxorg/ace/blob/master/lib/ace/keyboard/keybinding.js#L114
       # No easy way to selectively cancel shift+space, since we don't get access to the event.
       # Maybe we could temporarily set ourselves to read-only if we somehow know that a script is active?
-      exec: => 
+      exec: =>
         if @scriptRunning
           Backbone.Mediator.publish 'level:shift-space-pressed'
-        else 
+        else
           @ace.insert ' '
 
     addCommand
@@ -269,8 +273,8 @@ module.exports = class SpellView extends CocoView
     # @addZatannaSnippets()
     @highlightCurrentLine()
 
-  cast: (preload=false) ->
-    Backbone.Mediator.publish 'tome:cast-spell', spell: @spell, thang: @thang, preload: preload
+  cast: (preload=false, realTime=false) ->
+    Backbone.Mediator.publish 'tome:cast-spell', spell: @spell, thang: @thang, preload: preload, realTime: realTime
 
   notifySpellChanged: =>
     Backbone.Mediator.publish 'tome:spell-changed', spell: @spell
@@ -285,7 +289,7 @@ module.exports = class SpellView extends CocoView
 
   onManualCast: (e) ->
     cast = @$el.parent().length
-    @recompile cast
+    @recompile cast, e.realTime
     @focus() if cast
 
   onCodeReload: (e) ->
@@ -299,13 +303,16 @@ module.exports = class SpellView extends CocoView
   recompileIfNeeded: =>
     @recompile() if @recompileNeeded
 
-  recompile: (cast=true) ->
+  recompile: (cast=true, realTime=false) ->
     @setRecompileNeeded false
-    return if @spell.source is @getSource()
-    @spell.transpile @getSource()
-    @updateAether true, false
-    @cast() if cast
-    @notifySpellChanged()
+    hasChanged = @spell.source isnt @getSource()
+    if hasChanged
+      @spell.transpile @getSource()
+      @updateAether true, false
+    if cast and (hasChanged or realTime)
+      @cast(false, realTime)
+    if hasChanged
+      @notifySpellChanged()
 
   updateACEText: (source) ->
     @eventsSuppressed = true
@@ -472,7 +479,7 @@ module.exports = class SpellView extends CocoView
   onSessionWillSave: (e) ->
     return unless @spellHasChanged
     setTimeout(=>
-      unless @spellHasChanged
+      unless @destroyed or @spellHasChanged
         @$el.find('.save-status').finish().show().fadeOut(2000)
     , 1000)
     @spellHasChanged = false
@@ -510,7 +517,7 @@ module.exports = class SpellView extends CocoView
       spellThang.castAether = aether
       spellThang.aether = @spell.createAether thang
     #console.log thangID, @spell.spellKey, 'ran', aether.metrics.callsExecuted, 'times over', aether.metrics.statementsExecuted, 'statements, with max recursion depth', aether.metrics.maxDepth, 'and full flow/metrics', aether.metrics, aether.flow
-    @spell.transpile()
+    @spell.transpile()  # TODO: is there any way we can avoid doing this if it hasn't changed? Causes a slight hang.
     @updateAether false, false
 
   # --------------------------------------------------------------------------------------------------
diff --git a/app/views/play/level/tome/ThangListView.coffee b/app/views/play/level/tome/ThangListView.coffee
index 03ab371c1..2b09f44e8 100644
--- a/app/views/play/level/tome/ThangListView.coffee
+++ b/app/views/play/level/tome/ThangListView.coffee
@@ -29,6 +29,8 @@ module.exports = class ThangListView extends CocoView
       false
     ), @sortScoreForThang
     @muggleThangs = _.sortBy _.without(@thangs, @readwriteThangs..., @readThangs...), @sortScoreForThang
+    if @muggleThangs.length > 15
+      @muggleThangs = []  # Don't render a zillion of these. Slow, too long, maybe not useful.
 
   sortScoreForThang: (t) =>
     # Sort by my team, then most spells and fewest shared Thangs per spell,
@@ -73,6 +75,12 @@ module.exports = class ThangListView extends CocoView
     null
 
   adjustThangs: (spells, thangs) ->
+    # TODO: it would be nice to not have to do this any more, like if we migrate to the hero levels.
+    # Recreating all the ThangListEntryViews and their ThangAvatarViews is pretty slow.
+    # So they aren't even kept up-to-date during world streaming.
+    # Updating the existing subviews? Would be kind of complicated to get all the new thangs and spells propagated.
+    # I would do it, if I didn't think we were perhaps soon to not do the ThangList any more.
+    # Will temporary reduce the number of muggle thangs we're willing to draw.
     @spells = @options.spells = spells
     for entry in @entries
       entry.$el.remove()
diff --git a/app/views/play/level/tome/TomeView.coffee b/app/views/play/level/tome/TomeView.coffee
index fa20c5c45..246fae8d3 100644
--- a/app/views/play/level/tome/TomeView.coffee
+++ b/app/views/play/level/tome/TomeView.coffee
@@ -142,6 +142,9 @@ module.exports = class TomeView extends CocoView
       else
         delete @thangSpells[thangID]
         spell.removeThangID thangID for spell in @spells
+    for spellKey, spell of @spells when not spell.canRead()  # Make sure these get transpiled (they have no views).
+      spell.transpile()
+      spell.loaded = true
     null
 
   onSpellLoaded: (e) ->
@@ -152,10 +155,10 @@ module.exports = class TomeView extends CocoView
   onCastSpell: (e) ->
     # A single spell is cast.
     # Hmm; do we need to make sure other spells are all cast here?
-    @cast e?.preload
+    @cast e?.preload, e?.realTime
 
-  cast: (preload=false) ->
-    Backbone.Mediator.publish 'tome:cast-spells', spells: @spells, preload: preload
+  cast: (preload=false, realTime=false) ->
+    Backbone.Mediator.publish 'tome:cast-spells', spells: @spells, preload: preload, realTime: realTime
 
   onToggleSpellList: (e) ->
     @spellList.rerenderEntries()
@@ -209,6 +212,7 @@ module.exports = class TomeView extends CocoView
 
   spellFor: (thang, spellName) ->
     return null unless thang?.isProgrammable
+    return unless @thangSpells[thang.id]  # Probably in streaming mode, where we don't update until it's done.
     selectedThangSpells = (@spells[spellKey] for spellKey in @thangSpells[thang.id])
     if spellName
       spell = _.find selectedThangSpells, {name: spellName}