/**** 
* Classes
****/ 
// EnemyLaser class
var EnemyLaser = Container.expand(function (x, y) {
	var self = Container.call(this);
	var enemyLaserGraphics = self.attachAsset('enemylaser', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.x = x;
	self.y = y;
	self.speed = 10;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732) {
			self.destroy();
		}
	};
});
// EnemyShip class
var EnemyShip = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.attachAsset('enemyship', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 5;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732) {
			self.destroy();
		}
	};
	self.shoot = function () {
		var enemyLaser = new EnemyLaser(self.x, self.y + enemyGraphics.height / 2);
		game.addChild(enemyLaser);
		enemyLasers.push(enemyLaser);
	};
});
// Laser class
var Laser = Container.expand(function (x, y) {
	var self = Container.call(this);
	var laserGraphics = self.attachAsset('laser', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.x = x;
	self.y = y;
	self.speed = -15;
	self.update = function () {
		self.y += self.speed;
		if (self.y < 0) {
			self.destroy();
		}
	};
});
//<Assets used in the game will automatically appear here>
// SpaceShip class
var SpaceShip = Container.expand(function () {
	var self = Container.call(this);
	var shipGraphics = self.attachAsset('spaceship', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 10;
	self.update = function () {
		self.y = 2732 - 200;
	};
	self.shoot = function () {
		var laser = new Laser(self.x, self.y - shipGraphics.height / 2);
		game.addChild(laser);
		lasers.push(laser);
		LK.getSound('lasersound').play();
	};
});
// Star class
var Star = Container.expand(function () {
	var self = Container.call(this);
	var starGraphics = self.attachAsset('star', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 2;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732) {
			self.y = -starGraphics.height;
			self.x = Math.random() * 2048;
		}
	};
});

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

/**** 
* Game Code
****/ 
// Initialize arrays and variables
var spaceship;
var enemies = [];
var lasers = [];
var enemyLasers = [];
var stars = [];
var score = 0;
var scoreTxt = new Text2('0', {
	size: 150,
	fill: "#ffffff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Create spaceship
spaceship = new SpaceShip();
spaceship.x = 2048 / 2;
spaceship.y = 2732 - 200;
game.addChild(spaceship);
// Create and add stars
for (var i = 0; i < 50; i++) {
	var star = new Star();
	star.x = Math.random() * 2048;
	star.y = Math.random() * 2732;
	stars.push(star);
	game.addChild(star);
}
// Spawn enemies
function spawnEnemy() {
	var enemy = new EnemyShip();
	enemy.x = Math.random() * 2048;
	enemy.y = -100;
	enemies.push(enemy);
	game.addChild(enemy);
}
// Handle game updates
game.update = function () {
	// Update spaceship
	spaceship.update();
	// Update stars
	for (var i = stars.length - 1; i >= 0; i--) {
		stars[i].update();
	}
	// Update lasers
	for (var i = lasers.length - 1; i >= 0; i--) {
		lasers[i].update();
		if (lasers[i].y < 0) {
			lasers[i].destroy();
			lasers.splice(i, 1);
		}
	}
	// Update enemy lasers
	for (var i = enemyLasers.length - 1; i >= 0; i--) {
		enemyLasers[i].update();
		if (enemyLasers[i].y > 2732) {
			enemyLasers[i].destroy();
			enemyLasers.splice(i, 1);
		}
	}
	// Update enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		enemies[i].update();
		if (enemies[i].y > 2732) {
			enemies[i].destroy();
			enemies.splice(i, 1);
		}
	}
	// Check for collisions
	for (var i = lasers.length - 1; i >= 0; i--) {
		for (var j = enemies.length - 1; j >= 0; j--) {
			if (lasers[i].intersects(enemies[j])) {
				lasers[i].destroy();
				var destroyEffect = LK.getAsset('destroy', {
					anchorX: 0.5,
					anchorY: 0.5,
					x: enemies[j].x,
					y: enemies[j].y
				});
				game.addChild(destroyEffect);
				LK.setTimeout(function () {
					destroyEffect.destroy();
				}, 200);
				(function (enemyIndex, laserIndex) {
					LK.setTimeout(function () {
						if (enemies[enemyIndex]) {
							enemies[enemyIndex].destroy();
							enemies.splice(enemyIndex, 1);
						}
						if (lasers[laserIndex]) {
							lasers.splice(laserIndex, 1);
						}
						score++;
						scoreTxt.setText(score);
					}, 200);
				})(j, i);
				break;
			}
		}
	}
	for (var i = enemyLasers.length - 1; i >= 0; i--) {
		if (enemyLasers[i].intersects(spaceship)) {
			enemyLasers[i].destroy();
			enemyLasers.splice(i, 1);
			// Flash screen red for 1 second (1000ms) to show we are dead.
			LK.effects.flashScreen(0xff0000, 1000);
			// Show game over. The game will be automatically paused while game over is showing.
			LK.showGameOver(); // Calling this will destroy the 'Game' and reset entire game state.
			break;
		}
	}
	// Spawn enemies periodically
	if (LK.ticks % 60 == 0) {
		spawnEnemy();
	}
	// Enemies shoot periodically
	if (LK.ticks % 120 == 0) {
		for (var i = 0; i < enemies.length; i++) {
			enemies[i].shoot();
		}
	}
};
// Handle touch events
game.down = function (x, y, obj) {
	spaceship.shoot();
};
game.move = function (x, y, obj) {
	spaceship.x = x;
};
game.up = function (x, y, obj) {
	// No action needed on touch up
};

===================================================================
--- original.js
+++ change.js
@@ -181,15 +181,21 @@
 				game.addChild(destroyEffect);
 				LK.setTimeout(function () {
 					destroyEffect.destroy();
 				}, 200);
-				LK.setTimeout(function () {
-					enemies[j].destroy();
-					lasers.splice(i, 1);
-					enemies.splice(j, 1);
-					score++;
-					scoreTxt.setText(score);
-				}, 200);
+				(function (enemyIndex, laserIndex) {
+					LK.setTimeout(function () {
+						if (enemies[enemyIndex]) {
+							enemies[enemyIndex].destroy();
+							enemies.splice(enemyIndex, 1);
+						}
+						if (lasers[laserIndex]) {
+							lasers.splice(laserIndex, 1);
+						}
+						score++;
+						scoreTxt.setText(score);
+					}, 200);
+				})(j, i);
 				break;
 			}
 		}
 	}