var Mario = Container.expand(function () {
	var self = Container.call(this);
	var marioGraphics = self.createAsset('mario', 'Mario character', .5, .5);
	marioGraphics.scale.set(2);
	self.move = function () {
		self.x += 5;
		if (self.x > 2048) self.x = 0;
	};
	self.jump = function () {};
});
var Mushroom = Container.expand(function () {
	var self = Container.call(this);
	var mushroomGraphics = self.createAsset('mushroom', 'Mushroom', .5, .5);
	self.move = function () {};
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.createAsset('enemy', 'Enemy character', .5, .5);
	self.move = function () {};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var background = self.createAsset('background', 'Background image', 0, 0);
	background.scale.set(2);
	var mario = self.addChild(new Mario());
	var mushrooms = [];
	var enemies = [];
	mario.x = 1024;
	mario.y = 2732 - mario.height;
	mario.on('down', function (obj) {
		mario.jump();
	});
	stage.on('down', function (obj) {
		var mushroom = new Mushroom();
		mushroom.x = obj.event.getLocalPosition(self).x;
		mushroom.y = obj.event.getLocalPosition(self).y;
		mushrooms.push(mushroom);
		self.addChild(mushroom);
	});
	LK.on('tick', function () {
		mario.move();
		for (var i = 0; i < mushrooms.length; i++) {
			mushrooms[i].move();
			if (mario.intersects(mushrooms[i])) {
				mushrooms[i].destroy();
				mushrooms.splice(i, 1);
			}
		}
		for (var i = 0; i < enemies.length; i++) {
			enemies[i].move();
			if (mario.intersects(enemies[i])) {
				LK.effects.flashScreen(0xff0000, 1000);
				LK.showGameOver();
			}
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -19,8 +19,10 @@
 	self.move = function () {};
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
+	var background = self.createAsset('background', 'Background image', 0, 0);
+	background.scale.set(2);
 	var mario = self.addChild(new Mario());
 	var mushrooms = [];
 	var enemies = [];
 	mario.x = 1024;