/**** 
* Classes
****/ 
// Enemy class
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 5;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732) {
			self.destroy();
		}
	};
});
// EnemyBullet class
var EnemyBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.attachAsset('enemyBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 10;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732) {
			self.destroy();
		}
	};
});
// Hero class
var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroGraphics = self.attachAsset('hero', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 10;
	self.shoot = function () {
		var bullet = new HeroBullet();
		bullet.x = self.x;
		bullet.y = self.y - 50;
		game.addChild(bullet);
		heroBullets.push(bullet);
	};
});
// HeroBullet class
var HeroBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.attachAsset('heroBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = -15;
	self.update = function () {
		self.y += self.speed;
		if (self.y < 0) {
			self.destroy();
		}
	};
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x000000 // Black background
});

/**** 
* Game Code
****/ 
// Add stars to the background
for (var i = 0; i < 200; i++) {
	var star = LK.getAsset('star', {
		anchorX: 0.5,
		anchorY: 0.5,
		scaleX: Math.random() * 0.5,
		scaleY: Math.random() * 0.5,
		x: Math.random() * 2048,
		y: Math.random() * 2732
	});
	game.addChild(star);
}
// Add big stone to the game for protection
var bigStone = LK.getAsset('bigStone', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: 2048 / 2,
	y: 2732 / 2
});
game.addChild(bigStone);
// Initialize assets used in this game.
// Assets will be automatically created and loaded by the LK engine based on their usage in the code.
var hero = new Hero();
hero.x = 2048 / 2;
hero.y = 2732 - 150;
game.addChild(hero);
var enemies = [];
var heroBullets = [];
var enemyBullets = [];
game.down = function (x, y, obj) {
	hero.shoot();
};
game.update = function () {
	// Update hero bullets
	for (var i = heroBullets.length - 1; i >= 0; i--) {
		heroBullets[i].update();
		for (var j = enemies.length - 1; j >= 0; j--) {
			if (heroBullets[i].intersects(enemies[j])) {
				enemies[j].destroy();
				heroBullets[i].destroy();
				enemies.splice(j, 1);
				heroBullets.splice(i, 1);
				break;
			}
		}
	}
	// Update enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		enemies[i].update();
		if (enemies[i].intersects(hero)) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.showGameOver();
		}
		// Enemy shoots bullet
		if (LK.ticks % 120 == 0) {
			var bullet = new EnemyBullet();
			bullet.x = enemies[i].x;
			bullet.y = enemies[i].y + 50;
			game.addChild(bullet);
			enemyBullets.push(bullet);
		}
	}
	// Update enemy bullets
	for (var i = enemyBullets.length - 1; i >= 0; i--) {
		enemyBullets[i].update();
		if (enemyBullets[i].intersects(hero)) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.showGameOver();
		}
	}
	// Spawn enemies
	if (LK.ticks % 60 == 0) {
		var enemy = new Enemy();
		enemy.x = Math.random() * 2048;
		enemy.y = -50;
		game.addChild(enemy);
		enemies.push(enemy);
	}
	// Move hero
	if (dragNode) {
		hero.x = dragNode.x;
		hero.y = dragNode.y;
	}
};

===================================================================
--- original.js
+++ change.js
@@ -84,8 +84,16 @@
 		y: Math.random() * 2732
 	});
 	game.addChild(star);
 }
+// Add big stone to the game for protection
+var bigStone = LK.getAsset('bigStone', {
+	anchorX: 0.5,
+	anchorY: 0.5,
+	x: 2048 / 2,
+	y: 2732 / 2
+});
+game.addChild(bigStone);
 // Initialize assets used in this game.
 // Assets will be automatically created and loaded by the LK engine based on their usage in the code.
 var hero = new Hero();
 hero.x = 2048 / 2;