/**** 
* Classes
****/ 
// Bullet class
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	// Attach bullet asset
	var bulletGraphics = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Set bullet speed
	self.speed = -5;
	// Update function called every game tick
	self.update = function () {
		self.y += self.speed;
		// Check for collision with enemy
		var enemies = game.children.filter(function (child) {
			return child instanceof Enemy;
		});
		for (var i = 0; i < enemies.length; i++) {
			var enemy = enemies[i];
			if (self.intersects(enemy)) {
				// Destroy enemy and bullet on collision
				enemy.destroy();
				self.destroy();
				// Add a blasting effect
				var blast = self.attachAsset('blast', {
					anchorX: 0.5,
					anchorY: 0.5
				});
				blast.x = self.x;
				blast.y = self.y;
				game.addChild(blast);
				// Destroy the blast effect after a short delay
				LK.setTimeout(function () {
					blast.destroy();
				}, 500);
				break;
			}
		}
	};
});
// Enemy class
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	// Attach enemy asset
	var enemyGraphics = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Set enemy speed
	self.speed = 5;
	// Update function called every game tick
	self.update = function () {
		// Move enemy based on speed
		self.y += self.speed;
		// Enemy fires a bullet every 60 ticks
		if (LK.ticks % 60 == 0) {
			var enemyBullet = game.addChild(new EnemyBullet());
			// Set bullet initial position to enemy's position
			enemyBullet.x = self.x;
			enemyBullet.y = self.y;
			// Set bullet speed to move downwards
			enemyBullet.speed = 5;
		}
	};
});
// EnemyBullet class
var EnemyBullet = Container.expand(function () {
	var self = Container.call(this);
	// Attach bullet asset
	var bulletGraphics = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Set bullet speed
	self.speed = 5;
	// Update function called every game tick
	self.update = function () {
		self.y += self.speed;
	};
});
// Player class
var Player = Container.expand(function () {
	var self = Container.call(this);
	// Attach player asset
	var playerGraphics = self.attachAsset('player', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Set player speed
	self.speed = 5;
	// Update function called every game tick
	self.update = function () {
		// Player movement is handled in game.move event
	};
});

/**** 
* Initialize Game
****/ 
//<Assets used in the game will automatically appear here>
//<Write imports for supported plugins here>
var game = new LK.Game({
	backgroundColor: 0x000000
});

/**** 
* Game Code
****/ 
game.update = function () {
	// Spawn an enemy every 60 ticks
	if (LK.ticks % 60 == 0) {
		var enemy = game.addChild(new Enemy());
		// Set enemy initial position
		enemy.x = Math.random() * 2048;
		enemy.y = 0;
	}
};
var player = game.addChild(new Player());
// Set player initial position
player.x = 1024;
player.y = 2732 - player.height / 2 - 100;
// Add mouse move event to the game
game.move = function (x, y, obj) {
	// Move player only on x axis
	player.x = x;
};
game.down = function (x, y, obj) {
	// Create a bullet instance
	var bullet = game.addChild(new Bullet());
	// Set bullet initial position to player's position
	bullet.x = player.x;
	bullet.y = player.y;
};

===================================================================
--- original.js
+++ change.js
@@ -56,9 +56,9 @@
 		// Move enemy based on speed
 		self.y += self.speed;
 		// Enemy fires a bullet every 60 ticks
 		if (LK.ticks % 60 == 0) {
-			var enemyBullet = game.addChild(new Bullet());
+			var enemyBullet = game.addChild(new EnemyBullet());
 			// Set bullet initial position to enemy's position
 			enemyBullet.x = self.x;
 			enemyBullet.y = self.y;
 			// Set bullet speed to move downwards