var Player = Container.expand(function () {
	var self = Container.call(this);
	var playerGraphics = self.createAsset('player', 'Player character', .5, .5);
	self.gravity = 1;
	self.jumpForce = 20;
	self.velocityX = 0;
	self.velocityY = 0;
	self.setJumpForce = function (x, y) {
		var vectorMagnitude = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
		var maxMagnitude = 1000;
		if (vectorMagnitude > maxMagnitude) {
			x = x / vectorMagnitude * maxMagnitude;
			y = y / vectorMagnitude * maxMagnitude;
		}
		this.jumpForceX = x / 12.5;
		this.jumpForceY = y / 12.5;
	};
	self.jumping = false;
	self.onPlatform = false;
	self.update = function () {
		this.x += this.velocityX;
		this.y += this.velocityY;
		this.velocityY += this.gravity;
		this.velocityX *= 0.98;
		this.velocityY *= 0.98;
		if (this.y > 2732) {
			LK.showGameOver();
		}
		if (this.x < 0 || this.x > 2048) {
			this.velocityX *= -1;
		}
		if (this.velocityY >= 0) {
			this.jumping = false;
		} else if (this.velocityY < 0) {
			this.jumping = true;
			this.onPlatform = false;
		}
	};
});
var Platform = Container.expand(function () {
	var self = Container.call(this);
	var platformGraphics = self.createAsset('platform', 'Platform', .5, .5);
	self.hitTestAsset = self.createAsset('hitTest', 'Hit Test Asset', .5, .5);
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	stage.on('up', function (obj) {
		if (dragStart && player.onPlatform) {
			var pos = obj.event.getLocalPosition(self);
			player.setJumpForce(dragStart.x - pos.x, dragStart.y - pos.y);
			player.velocityX = player.jumpForceX;
			player.velocityY = player.jumpForceY;
			dragStart = null;
		}
	});
	stage.on('move', function (obj) {
		if (dragStart) {
			var pos = obj.event.getLocalPosition(self);
		}
	});
	var platforms = [];
	var platformSpeed = 0;
	var player = self.addChild(new Player());
	player.x = 2048 / 2;
	player.y = 2732 - player.height;
	var firstJump = false;
	for (var i = 0; i < 6; i++) {
		var platform = new Platform();
		if (i == 0) {
			platform.x = player.x;
			platform.y = player.y + player.height;
		} else {
			platform.x = Math.random() * 2048;
			platform.y = i * (2732 / 6);
		}
		platforms.push(platform);
		self.addChild(platform);
	}
	LK.on('tick', function () {
		player.update();
		if (player.y < 2732 / 2) {
			platformSpeed = Math.min(platformSpeed + 0.1, 5);
		} else {
			platformSpeed = Math.max(platformSpeed - 0.1, 0);
		}
		for (var i = 0; i < platforms.length; i++) {
			platforms[i].y += platformSpeed;
		}
		player.y += platformSpeed;
		for (var i = 0; i < platforms.length; i++) {
			if (player.intersects(platforms[i]) && !player.jumping && player.y + player.height / 2 < platforms[i].y) {
				player.y = platforms[i].y - player.height / 2 - platforms[i].height / 2;
				player.velocityY = 0;
				player.velocityX *= 0.8;
				player.onPlatform = true;
			} else if (platforms[i].y - platforms[i].height > 2732) {
				platforms[i].y = -platforms[i].height;
				platforms[i].x = Math.random() * 2048;
			}
		}
	});
	var dragStart = null;
	stage.on('down', function (obj) {
		dragStart = obj.event.getLocalPosition(self);
	});
});

===================================================================
--- original.js
+++ change.js
@@ -39,9 +39,9 @@
 });
 var Platform = Container.expand(function () {
 	var self = Container.call(this);
 	var platformGraphics = self.createAsset('platform', 'Platform', .5, .5);
-	var hitTestAsset = self.createAsset('hitTest', 'Hit Test Asset', .5, .5);
+	self.hitTestAsset = self.createAsset('hitTest', 'Hit Test Asset', .5, .5);
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
 	stage.on('up', function (obj) {