var HeroBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.createAsset('heroBullet', 'Hero Bullet Graphics', .5, .5);
	self.speed = -10;
	self.move = function () {
		self.x += self.speedX;
		self.y += self.speedY;
	};
	self.timer = LK.setTimeout(function () {
		self.destroy();
	}, 5000);
});
var EnemyBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.createAsset('enemyBullet', 'Enemy Bullet Graphics', .5, .5);
	self.speed = 10;
	self.move = function () {
		self.x += self.speed;
	};
	self.timer = LK.setTimeout(function () {
		self.destroy();
	}, 5000);
});
var Hero = Container.expand(function () {
	var self = Container.call(this);
	self.update = function () {
		if (self.dx && self.dy) {
			self.x -= self.dx;
			self.y -= self.dy;
			self.dx *= 0.99;
			self.dy *= 0.99;
			if (Math.abs(self.dx) < 0.01 && Math.abs(self.dy) < 0.01) {
				self.dx = 0;
				self.dy = 0;
			}
		}
	};
	var heroGraphics = self.createAsset('hero', 'Hero character', .5, .5);
	self.knockback = function (dx, dy) {
		self.dx = -dx * 116.886;
		self.dy = -dy * 116.886;
	};
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.createAsset('enemy', 'Enemy character', .5, .5);
	self.health = 100;
	self.followHero = function (hero) {
		var dx = hero.x - self.x;
		var dy = hero.y - self.y;
		var mag = Math.sqrt(dx * dx + dy * dy);
		self.x += 3.85 * dx / mag;
		self.y += 3.85 * dy / mag;
	};
	self.hit = function () {
		self.health -= 10;
		if (self.health <= 0) {
			self.destroy();
		}
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	LK.stageContainer.setBackgroundColor(0x000000);
	var hero = self.addChild(new Hero());
	var enemy = self.addChild(new Enemy());
	hero.x = 1024;
	hero.y = 1366;
	enemy.x = 1024;
	enemy.y = 1366 - 200;
	var heroBullets = [];
	var enemyBullets = [];
	var isGameOver = false;
	var tickOffset = 0;
	var fpsCounter = new Text2('0', {
		size: 50,
		fill: '#ffffff'
	});
	LK.gui.topCenter.addChild(fpsCounter);
	var lastTick = Date.now();
	var frameCount = 0;
	var gameLoop = function () {
		if (isGameOver) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.showGameOver();
			return;
		}
		frameCount++;
		var now = Date.now();
		if (now - lastTick >= 1000) {
			fpsCounter.setText(frameCount);
			frameCount = 0;
			lastTick = now;
		}
		hero.update();
		enemy.followHero(hero);
		for (var a = heroBullets.length - 1; a >= 0; a--) {
			heroBullets[a].move();
			if (heroBullets[a].y < -50 || heroBullets[a].y > 2732 + 50 || heroBullets[a].x < -50 || heroBullets[a].x > 2048 + 50) {
				heroBullets[a].destroy();
				heroBullets.splice(a, 1);
			} else if (heroBullets[a] && enemy && heroBullets[a].intersects(enemy)) {
				enemy.hit();
				heroBullets[a].destroy();
				heroBullets.splice(a, 1);
			}
		}
		for (var a = enemyBullets.length - 1; a >= 0; a--) {
			if (enemyBullets[a]) {
				enemyBullets[a].move();
				if (enemyBullets[a].y > 2732 + 50) {
					enemyBullets[a].destroy();
					enemyBullets.splice(a, 1);
				}
			}
		}
		var lastShot = 0;
		var bulletCount = 0;
		stage.on('down', function (obj) {
			var event = obj.event;
			var pos = event.getLocalPosition(self);
			var newBullet = new HeroBullet();
			newBullet.x = hero.x;
			newBullet.y = hero.y;
			var dx = pos.x - hero.x;
			var dy = pos.y - hero.y;
			var mag = Math.sqrt(dx * dx + dy * dy);
			newBullet.speedX = 10 * dx / mag;
			newBullet.speedY = 10 * dy / mag;
			heroBullets.push(newBullet);
			self.addChild(newBullet);
			hero.knockback(-dx / (mag * 10), -dy / (mag * 10));
		});
		if (bulletCount > 0) bulletCount--;
		requestAnimationFrame(gameLoop);
	};
	requestAnimationFrame(gameLoop);
	;
});

===================================================================
--- original.js
+++ change.js
@@ -78,12 +78,13 @@
 	});
 	LK.gui.topCenter.addChild(fpsCounter);
 	var lastTick = Date.now();
 	var frameCount = 0;
-	LK.on('tick', function () {
+	var gameLoop = function () {
 		if (isGameOver) {
 			LK.effects.flashScreen(0xff0000, 1000);
 			LK.showGameOver();
+			return;
 		}
 		frameCount++;
 		var now = Date.now();
 		if (now - lastTick >= 1000) {
@@ -93,24 +94,25 @@
 		}
 		hero.update();
 		enemy.followHero(hero);
 		for (var a = heroBullets.length - 1; a >= 0; a--) {
-			var bullet = heroBullets[a];
-			bullet.move();
-			if (bullet.y < -50 || bullet.y > 2732 + 50 || bullet.x < -50 || bullet.x > 2048 + 50 || bullet && enemy && bullet.intersects(enemy)) {
-				if (bullet && enemy && bullet.intersects(enemy)) {
-					enemy.hit();
-				}
-				bullet.destroy();
+			heroBullets[a].move();
+			if (heroBullets[a].y < -50 || heroBullets[a].y > 2732 + 50 || heroBullets[a].x < -50 || heroBullets[a].x > 2048 + 50) {
+				heroBullets[a].destroy();
 				heroBullets.splice(a, 1);
+			} else if (heroBullets[a] && enemy && heroBullets[a].intersects(enemy)) {
+				enemy.hit();
+				heroBullets[a].destroy();
+				heroBullets.splice(a, 1);
 			}
 		}
 		for (var a = enemyBullets.length - 1; a >= 0; a--) {
-			var bullet = enemyBullets[a];
-			bullet.move();
-			if (bullet.y > 2732 + 50) {
-				bullet.destroy();
-				enemyBullets.splice(a, 1);
+			if (enemyBullets[a]) {
+				enemyBullets[a].move();
+				if (enemyBullets[a].y > 2732 + 50) {
+					enemyBullets[a].destroy();
+					enemyBullets.splice(a, 1);
+				}
 			}
 		}
 		var lastShot = 0;
 		var bulletCount = 0;
@@ -128,9 +130,10 @@
 			heroBullets.push(newBullet);
 			self.addChild(newBullet);
 			hero.knockback(-dx / (mag * 10), -dy / (mag * 10));
 		});
-		LK.on('tick', function () {
-			if (bulletCount > 0) bulletCount--;
-		});
-	});
+		if (bulletCount > 0) bulletCount--;
+		requestAnimationFrame(gameLoop);
+	};
+	requestAnimationFrame(gameLoop);
+	;
 });