var Opponent = Container.expand(function () {
	var self = Container.call(this);
	var opponentGraphics = self.createAsset('opponent', 'Opponent Graphics', .5, .5);
	opponentGraphics.scale.set(4);
	self.speed = -3;
	self.move = function () {
		self.x += self.speed;
	};
});
var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroGraphics = self.createAsset('hero', 'Hero character', .5, .5);
	heroGraphics.scale.set(6);
	self.speed = 5;
	self.move = function () {};
	self.punch = function () {};
});
var Punch = Container.expand(function () {
	var self = Container.call(this);
	self.velocity = {
		x: 0,
		y: 0
	};
	self.setVelocity = function (targetX, targetY) {
		var dx = targetX - self.x;
		var dy = targetY - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		self.velocity.x = self.speed * (dx / distance);
		self.velocity.y = self.speed * (dy / distance);
	};
	self.move = function () {
		self.x += self.velocity.x;
		self.y += self.velocity.y;
	};
	var punchGraphics = self.createAsset('punch', 'Punch Graphics', .5, .5);
	punchGraphics.scale.set(2);
	punchGraphics.rotation = Math.PI / 2;
	self.speed = 15;
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var background = self.createAsset('boxingRing', 'Boxing Ring Background', 0, 0);
	background.scale.set(LK.stage.width / background.width, LK.stage.height / background.height);
	self.addChildAt(background, 0);
	var hero = self.addChild(new Hero());
	var enemies = [];
	var punches = [];
	var opponents = [];
	var opponentSpawnRate = 120;
	var opponentSpawnCounter = 0;
	var scoreTxt = new Text2('0', {
		size: 150,
		fill: "#ffffff"
	});
	LK.gui.topCenter.addChild(scoreTxt);
	var isGameOver = false;
	var tickOffset = 0;
	hero.x = hero.width / 2;
	hero.y = 2732 / 2;
	var punchCooldown = 500;
	var lastPunchTime = 0;
	LK.stage.on('down', function (obj) {
		var currentTime = Date.now();
		if (currentTime - lastPunchTime >= punchCooldown) {
			var event = obj.event;
			var tapPosition = event.getLocalPosition(self);
			var punch = new Punch();
			punch.x = hero.x;
			punch.y = hero.y;
			punch.setVelocity(tapPosition.x, tapPosition.y);
			punches.push(punch);
			self.addChild(punch);
			LK.effects.flashObject(hero, 0xffcc00, 100);
			lastPunchTime = currentTime;
		}
	});
	LK.on('tick', function () {
		hero.move();
		for (var i = punches.length - 1; i >= 0; i--) {
			var punch = punches[i];
			punch.move();
		}
		if (opponentSpawnCounter++ >= opponentSpawnRate) {
			var opponent = new Opponent();
			opponent.x = LK.stage.width;
			opponent.y = Math.random() * (LK.stage.height - opponent.height) + opponent.height / 2;
			opponents.push(opponent);
			self.addChild(opponent);
			opponentSpawnCounter = 0;
		}
		for (var j = opponents.length - 1; j >= 0; j--) {
			var opponent = opponents[j];
			opponent.move();
			if (opponent.x + opponent.width / 2 < 0) {
				opponent.destroy();
				opponents.splice(j, 1);
			}
		}
		if (isGameOver) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.showGameOver();
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -1,4 +1,13 @@
+var Opponent = Container.expand(function () {
+	var self = Container.call(this);
+	var opponentGraphics = self.createAsset('opponent', 'Opponent Graphics', .5, .5);
+	opponentGraphics.scale.set(4);
+	self.speed = -3;
+	self.move = function () {
+		self.x += self.speed;
+	};
+});
 var Hero = Container.expand(function () {
 	var self = Container.call(this);
 	var heroGraphics = self.createAsset('hero', 'Hero character', .5, .5);
 	heroGraphics.scale.set(6);
@@ -35,8 +44,11 @@
 	self.addChildAt(background, 0);
 	var hero = self.addChild(new Hero());
 	var enemies = [];
 	var punches = [];
+	var opponents = [];
+	var opponentSpawnRate = 120;
+	var opponentSpawnCounter = 0;
 	var scoreTxt = new Text2('0', {
 		size: 150,
 		fill: "#ffffff"
 	});
@@ -67,8 +79,24 @@
 		for (var i = punches.length - 1; i >= 0; i--) {
 			var punch = punches[i];
 			punch.move();
 		}
+		if (opponentSpawnCounter++ >= opponentSpawnRate) {
+			var opponent = new Opponent();
+			opponent.x = LK.stage.width;
+			opponent.y = Math.random() * (LK.stage.height - opponent.height) + opponent.height / 2;
+			opponents.push(opponent);
+			self.addChild(opponent);
+			opponentSpawnCounter = 0;
+		}
+		for (var j = opponents.length - 1; j >= 0; j--) {
+			var opponent = opponents[j];
+			opponent.move();
+			if (opponent.x + opponent.width / 2 < 0) {
+				opponent.destroy();
+				opponents.splice(j, 1);
+			}
+		}
 		if (isGameOver) {
 			LK.effects.flashScreen(0xff0000, 1000);
 			LK.showGameOver();
 		}