diff --git a/app/Game/Core/Physics/Doll.js b/app/Game/Core/Physics/Doll.js
index 06a4b97..56f1ef0 100644
--- a/app/Game/Core/Physics/Doll.js
+++ b/app/Game/Core/Physics/Doll.js
@@ -1,4 +1,4 @@
-define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detector"], function(Box2D, Settings, Detector) {
+define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detector"], function(Box2D, Settings, CollisionDetector) {
 
     function Doll (physicsEngine, id){
         this.id = id;
@@ -18,7 +18,7 @@ define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detecto
         bodyDef.fixedRotation = true;
         bodyDef.linearDamping = Settings.PLAYER_LINEAR_DAMPING;
         bodyDef.type = Box2D.Dynamics.b2Body.b2_dynamicBody;
-        bodyDef.userData = Detector.IDENTIFIER.PLAYER + '-' + this.id;
+        bodyDef.userData = CollisionDetector.IDENTIFIER.PLAYER + '-' + this.id;
 
         this.body = world.CreateBody(bodyDef);
 
@@ -32,14 +32,14 @@ define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detecto
         headShape.SetLocalPosition(new Box2D.Common.Math.b2Vec2(0 / Settings.RATIO, -37 / Settings.RATIO));
         fixtureDef.shape = headShape;
         fixtureDef.isSensor = false;
-        fixtureDef.userData = Detector.IDENTIFIER.PLAYER_HEAD;
+        fixtureDef.userData = CollisionDetector.IDENTIFIER.PLAYER_HEAD;
         this.body.CreateFixture(fixtureDef);
 
         var bodyShape = new Box2D.Collision.Shapes.b2PolygonShape();
         bodyShape.SetAsOrientedBox(5 / Settings.RATIO, 16 / Settings.RATIO, new Box2D.Common.Math.b2Vec2(0 / Settings.RATIO, -21 / Settings.RATIO));
         fixtureDef.shape = bodyShape;
         fixtureDef.isSensor = false;
-        fixtureDef.userData = Detector.IDENTIFIER.PLAYER_CHEST;
+        fixtureDef.userData = CollisionDetector.IDENTIFIER.PLAYER_CHEST;
         this.body.CreateFixture(fixtureDef);
 
         var legsShape = new Box2D.Collision.Shapes.b2CircleShape();
@@ -48,7 +48,7 @@ define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detecto
         fixtureDef.shape = legsShape;
         fixtureDef.friction = Settings.PLAYER_FRICTION;
         fixtureDef.isSensor = false;
-        fixtureDef.userData = Detector.IDENTIFIER.PLAYER_LEGS;
+        fixtureDef.userData = CollisionDetector.IDENTIFIER.PLAYER_LEGS;
 
         this.legs = this.body.CreateFixture(fixtureDef);
 
@@ -57,7 +57,7 @@ define(["Lib/Vendor/Box2D", "Game/Config/Settings", "Game/Core/Collision/Detecto
         feetShape.SetLocalPosition(new Box2D.Common.Math.b2Vec2(0 / Settings.RATIO, 0 / Settings.RATIO));
         fixtureDef.shape = feetShape;
         fixtureDef.isSensor = true;
-        fixtureDef.userData = Detector.IDENTIFIER.FOOTSENSOR;
+        fixtureDef.userData = CollisionDetector.IDENTIFIER.FOOTSENSOR;
         this.body.CreateFixture(fixtureDef);
 
         this.body.SetActive(false);
diff --git a/app/Game/Core/Physics/Engine.js b/app/Game/Core/Physics/Engine.js
index 47605d1..f5323eb 100755
--- a/app/Game/Core/Physics/Engine.js
+++ b/app/Game/Core/Physics/Engine.js
@@ -1,16 +1,16 @@
-define(["Chuck/Settings", "Client/Dom", "Vendor/Box2D", "Chuck/Collision/Detector"], function(Settings, Dom, Box2D, CollisionDetector){
+define([
+	"Game/Config/Settings",
+	"Lib/Vendor/Box2D",
+	"Game/Core/Collision/Detector"
+],
+
+function(Settings, Box2D, CollisionDetector) {
 
 	function Engine () {
-	    this.world;
-	    this.init();
-	}
-
-	Engine.prototype.init = function() {
-	    this.world = new Box2D.Dynamics.b2World(new Box2D.Common.Math.b2Vec2(0, Settings.BOX2D_GRAVITY), Settings.BOX2D_ALLOW_SLEEP);
-
-	    if(Settings.IS_BROWSER_ENVIRONMENT && Settings.DEBUG_MODE) {
-	    	this.setupDebugDraw();
-	    }
+	    this.world = new Box2D.Dynamics.b2World(
+	    	new Box2D.Common.Math.b2Vec2(0, Settings.BOX2D_GRAVITY),
+	    	Settings.BOX2D_ALLOW_SLEEP
+	    );
 	}
 
 	Engine.prototype.getWorld = function() {
@@ -19,36 +19,10 @@ define(["Chuck/Settings", "Client/Dom", "Vendor/Box2D", "Chuck/Collision/Detecto
 
 	Engine.prototype.setCollisionDetector = function(me) {
 		
-	    var detector = new CollisionDetector(me);
+	    var detector = new CollisionDetector(me); // FIXME: check if core collision detector works
 	    this.world.SetContactListener(detector.getListener());
 	}
 
-	Engine.prototype.setupDebugDraw = function() {
-	    //var debugSprite = Settings.DEBUG_DRAW_CANVAS_SPRITE;
-		var debugSprite = Dom.getDebugCanvas().getContext("2d");
-
-	    // set debug draw
-	    var debugDraw = new Box2D.Dynamics.b2DebugDraw();
-
-	    debugDraw.SetSprite(debugSprite);
-	    debugDraw.SetDrawScale(Settings.RATIO);
-		debugDraw.SetFillAlpha(0.5);
-		debugDraw.SetLineThickness(1.0);
-
-	    debugDraw.SetFlags(null
-	        | Box2D.Dynamics.b2DebugDraw.e_shapeBit 
-		    | Box2D.Dynamics.b2DebugDraw.e_jointBit 
-		    //| Box2D.Dynamics.b2DebugDraw.e_coreShapeBit
-		    //| Box2D.Dynamics.b2DebugDraw.e_aabbBit
-		    //| Box2D.Dynamics.b2DebugDraw.e_centerOfMassBit
-		    //| Box2D.Dynamics.b2DebugDraw.e_obbBit
-		    //| Box2D.Dynamics.b2DebugDraw.e_pairBit
-		);
-
-	    this.world.SetDebugDraw(debugDraw);
-	    this.world.SetWarmStarting(true);
-	}
-
 	Engine.prototype.createBody = function(bodyDef) {
 	    return this.world.CreateBody(bodyDef);
 	}
@@ -56,7 +30,6 @@ define(["Chuck/Settings", "Client/Dom", "Vendor/Box2D", "Chuck/Collision/Detecto
 	Engine.prototype.update = function() {
 	    this.world.Step(Settings.BOX2D_TIME_STEP, Settings.BOX2D_VELOCITY_ITERATIONS, Settings.BOX2D_POSITION_ITERATIONS);
 	    this.world.ClearForces();
-	    this.world.DrawDebugData();
 	}
 
 	return Engine;