var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroGraphics = self.createAsset('hero', 'Hero character', .5, .5);
	self.move = function () {};
	self.shoot = function () {};
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.createAsset('enemy', 'Enemy character', .5, .5);
	self.move = function () {
		self.x += Math.random() * 10 - 5;
		self.y += Math.random() * 10 - 5;
	};
	self.shoot = function () {};
});
var HeroBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.createAsset('heroBullet', 'Hero Bullet', .5, .5);
	self.move = function () {};
});
var EnemyBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.createAsset('enemyBullet', 'Enemy Bullet', .5, .5);
	self.move = function () {};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var hero = self.addChild(new Hero());
	var enemies = [];
	var heroBullets = [];
	var enemyBullets = [];
	hero.x = 2048 / 2;
	hero.y = 2732 / 2;
	for (var i = 0; i < 5; i++) {
		var enemy = new Enemy();
		enemy.x = Math.random() * 2048;
		enemy.y = Math.random() * 2732;
		enemies.push(enemy);
		self.addChild(enemy);
	}
	LK.on('tick', function () {
		hero.move();
		enemies.forEach(function (enemy) {
			enemy.move();
		});
		heroBullets.forEach(function (bullet) {
			bullet.move();
		});
		enemyBullets.forEach(function (bullet) {
			bullet.move();
		});
		if (LK.ticks % 60 == 0) {
			var heroBullet = new HeroBullet();
			heroBullet.x = hero.x;
			heroBullet.y = hero.y;
			heroBullets.push(heroBullet);
			self.addChild(heroBullet);
			enemies.forEach(function (enemy) {
				var enemyBullet = new EnemyBullet();
				enemyBullet.x = enemy.x;
				enemyBullet.y = enemy.y;
				enemyBullets.push(enemyBullet);
				self.addChild(enemyBullet);
			});
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -1,13 +1,17 @@
 var Hero = Container.expand(function () {
 	var self = Container.call(this);
+	var heroGraphics = self.createAsset('hero', 'Hero character', .5, .5);
 	self.move = function () {};
 	self.shoot = function () {};
 });
 var Enemy = Container.expand(function () {
 	var self = Container.call(this);
 	var enemyGraphics = self.createAsset('enemy', 'Enemy character', .5, .5);
-	self.move = function () {};
+	self.move = function () {
+		self.x += Math.random() * 10 - 5;
+		self.y += Math.random() * 10 - 5;
+	};
 	self.shoot = function () {};
 });
 var HeroBullet = Container.expand(function () {
 	var self = Container.call(this);