var Galaxy = Container.expand(function () {
	var self = Container.call(this);
	var galaxyGraphics = self.createAsset('galaxy', 'Galaxy Graphics', 0.5, 0.5);
	galaxyGraphics.scale.set(4);
});
var Sun = Container.expand(function () {
	var self = Container.call(this);
	var sunGraphics = self.createAsset('sun', 'Sun Graphics', 0.5, 0.5);
	sunGraphics.scale.set(4);
});
var Dot = Container.expand(function () {
	var self = Container.call(this);
	var dotGraphics = self.createAsset('dot', 'Dot Graphics', 0.5, 0.5);
	dotGraphics.scale.set(0.5);
	self.speed = {
		x: (Math.random() * 10 - 5) / 6,
		y: (Math.random() * 10 - 5) / 6
	};
	self.move = function () {
		self.x += self.speed.x;
		self.y += self.speed.y;
		if (self.x < 0 || self.x > 2048 || self.y < 0 || self.y > 2732) {
			self.x = Math.random() * 2048;
			self.y = Math.random() * 2732;
		}
	};
});
var Paddle = Container.expand(function () {
	var self = Container.call(this);
	var paddleGraphics = self.createAsset('paddle', 'Paddle Graphics', 0.5, 0.5);
	self.speed = 20;
	self.move = function (direction) {
		self.y += direction * self.speed;
	};
});
var Ball = Container.expand(function () {
	var self = Container.call(this);
	var ballGraphics = self.createAsset('ball', 'Ball Graphics', 0.5, 0.5);
	self.speed = {
		x: 10,
		y: 10
	};
	self.move = function () {
		self.x += self.speed.x;
		self.y += self.speed.y;
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var galaxy = self.addChild(new Galaxy());
	galaxy.x = 2048 / 2;
	galaxy.y = 2732 / 2;
	var sun = self.addChild(new Sun());
	sun.x = 2048 / 2;
	sun.y = 2732 / 2;
	var playerPaddle = self.addChildAt(new Paddle(), self.children.length);
	var aiPaddle = self.addChildAt(new Paddle(), self.children.length);
	var ball = self.addChildAt(new Ball(), self.children.length);
	var paddles = [playerPaddle, aiPaddle];
	var score = 0;
	playerPaddle.x = 100;
	playerPaddle.y = 2732 / 2;
	aiPaddle.x = 2048 - 100;
	aiPaddle.y = 2732 / 2;
	ball.x = 2048 / 2;
	ball.y = 2732 / 2;
	var scoreTxt = new Text2('0', {
		size: 150,
		fill: "#ffffff"
	});
	scoreTxt.anchor.set(.5, 0);
	LK.gui.topCenter.addChild(scoreTxt);
	var dots = [];
	for (var i = 0; i < 100; i++) {
		var dot = new Dot();
		dot.x = Math.random() * 2048;
		dot.y = Math.random() * 2732;
		dots.push(dot);
	}
	for (var i = 0; i < dots.length; i++) {
		self.addChild(dots[i]);
	}
	var targetY = playerPaddle.y;
	stage.on('down', function (obj) {
		var event = obj.event;
		var pos = event.getLocalPosition(self);
		targetY = pos.y;
	});
	stage.on('move', function (obj) {
		var event = obj.event;
		var pos = event.getLocalPosition(self);
		targetY = pos.y;
	});
	LK.on('tick', function () {
		if (targetY < playerPaddle.y) {
			playerPaddle.move(-1);
		} else if (targetY > playerPaddle.y) {
			playerPaddle.move(1);
		}
	});
	LK.on('tick', function () {
		ball.move();
		if (ball.y < aiPaddle.y) {
			aiPaddle.move(-1);
		} else if (ball.y > aiPaddle.y) {
			aiPaddle.move(1);
		}
		for (var i = 0; i < paddles.length; i++) {
			if (ball.intersects(paddles[i])) {
				var hitPoint = ball.y - paddles[i].y;
				var hitRatio = hitPoint / paddles[i].height;
				ball.speed.y += hitRatio * 10;
				if (ball.speed.x > 0 && ball.x < paddles[i].x || ball.speed.x < 0 && ball.x > paddles[i].x) {
					ball.speed.x *= -1;
				}
			}
		}
		if (ball.y <= 0 || ball.y >= 2732) {
			ball.speed.y *= -1;
		}
		if (ball.x <= 0) {
			LK.showGameOver();
		}
		if (ball.x >= 2048) {
			score++;
			ball.x = 2048 / 2;
			ball.y = 2732 / 2;
			ball.speed.x = 10;
			ball.speed.y = 10;
		}
		scoreTxt.setText(score.toString());
		for (var i = 0; i < dots.length; i++) {
			dots[i].move();
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -1,4 +1,9 @@
+var Galaxy = Container.expand(function () {
+	var self = Container.call(this);
+	var galaxyGraphics = self.createAsset('galaxy', 'Galaxy Graphics', 0.5, 0.5);
+	galaxyGraphics.scale.set(4);
+});
 var Sun = Container.expand(function () {
 	var self = Container.call(this);
 	var sunGraphics = self.createAsset('sun', 'Sun Graphics', 0.5, 0.5);
 	sunGraphics.scale.set(4);
@@ -41,8 +46,11 @@
 	};
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
+	var galaxy = self.addChild(new Galaxy());
+	galaxy.x = 2048 / 2;
+	galaxy.y = 2732 / 2;
 	var sun = self.addChild(new Sun());
 	sun.x = 2048 / 2;
 	sun.y = 2732 / 2;
 	var playerPaddle = self.addChildAt(new Paddle(), self.children.length);