var Base = Container.expand(function () {
	var self = Container.call(this);
	var baseGraphics = self.createAsset('base', 'Base Graphics', .5, .5);
	self.health = 100;
	self.updateHealth = function () {};
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.createAsset('enemy', 'Enemy Graphics', .5, .5);
	self.speed = 2;
	self.move = function () {
		self.y += self.speed;
	};
	self.attack = function () {};
});
var HeroBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.createAsset('bullet', 'Bullet Graphics', .5, .5);
	self.speed = 5;
	self.move = function () {};
});
var Spawner = Container.expand(function (x, y) {
	var self = Container.call(this);
	var spawnerGraphics = self.createAsset('spawner', 'Spawner Graphics', .5, .5);
	self.x = x;
	self.y = y;
	self.spawnEnemy = function () {
		var enemy = new Enemy();
		enemy.x = self.x;
		enemy.y = self.y;
		self.parent.enemies.push(enemy);
		self.parent.addChild(enemy);
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var background = self.createAsset('background', 'Game Background', 0, 0);
	background.width = 2048;
	background.height = 2732;
	self.addChildAt(background, self.children.length);
	self.coins = 0;
	var coinDisplay = new Text2('Coins: ' + self.coins, {
		size: 100,
		fill: "#ffffff",
		align: 'center'
	});
	coinDisplay.anchor.set(0.5, 0.5);
	coinDisplay.x = 2048 / 2;
	coinDisplay.y = 2732 / 2;
	LK.gui.addChild(coinDisplay);
	var self = Container.call(this);
	self.enemies = [];
	var base = self.addChild(new Base());
	var bullets = [];
	base.x = 2048 / 2;
	base.y = 2732 - base.height / 2;
	var spawner1 = self.addChild(new Spawner(2048 / 6, 200));
	var spawner2 = self.addChild(new Spawner(2048 / 2, 200));
	var spawner3 = self.addChild(new Spawner(2048 / 6 * 5, 200));
	var spawner1Timer = LK.setInterval(function () {
		spawner1.spawnEnemy();
	}, 3000);
	spawner1.spawnEnemy();
	var spawner2Timer = LK.setInterval(function () {
		spawner2.spawnEnemy();
	}, 4000);
	spawner2.spawnEnemy();
	var spawner3Timer = LK.setInterval(function () {
		spawner3.spawnEnemy();
	}, 5000);
	spawner3.spawnEnemy();
	var fireBullet = function (x, y) {
		var bullet = new HeroBullet();
		bullet.x = x;
		bullet.y = y;
		bullets.push(bullet);
		self.addChild(bullet);
	};
	self.on('down', function (obj) {
		var pos = obj.event.getLocalPosition(self);
		fireBullet(pos.x, pos.y);
	});
	LK.on('tick', function () {
		for (var i = 0; i < self.enemies.length; i++) {
			self.enemies[i].move();
			if (self.enemies[i].intersects(base)) {
				self.enemies[i].attack();
				self.enemies[i].destroy();
				self.enemies.splice(i, 1);
				i--;
			}
		}
		for (var i = 0; i < bullets.length; i++) {
			bullets[i].move();
			for (var j = 0; j < self.enemies.length; j++) {
				if (bullets[i].intersects(self.enemies[j])) {
					bullets[i].destroy();
					bullets.splice(i, 1);
					i--;
					self.enemies[j].destroy();
					self.enemies.splice(j, 1);
					self.coins++;
					coinDisplay.setText('Coins: ' + self.coins.toString());
					break;
				}
			}
		}
		if (base.health <= 0 || self.enemies.some(enemy => enemy.y >= 2732 - enemy.height / 2)) {
			LK.showGameOver();
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -36,9 +36,9 @@
 	var self = Container.call(this);
 	var background = self.createAsset('background', 'Game Background', 0, 0);
 	background.width = 2048;
 	background.height = 2732;
-	self.addChildAt(background, 0);
+	self.addChildAt(background, self.children.length);
 	self.coins = 0;
 	var coinDisplay = new Text2('Coins: ' + self.coins, {
 		size: 100,
 		fill: "#ffffff",