var TargetIndicator = Container.expand(function () {
	var self = Container.call(this);
	var indicatorGraphics = XS.getAsset('indicator', 'Target Indicator', .5, .5);
	self.addChild(indicatorGraphics);
});
var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroGraphics = XS.getAsset('hero', 'Hero character', .5, .5);
	heroGraphics.rotation = -Math.PI / 2;
	self.addChild(heroGraphics);
	self.target = {
		x: 2048 / 2,
		y: 2732 / 2
	};
	self.isMoving = false;
	self.move = function () {
		var dx = self.target.x - self.x;
		var dy = self.target.y - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		if (distance > 5) {
			self.x += 5 * (dx / distance);
			self.y += 5 * (dy / distance);
			self.rotation = Math.atan2(dy, dx);
			self.isMoving = true;
		} else {
			self.isMoving = false;
		}
	};
	self.shoot = function (target) {
		var bullet = new Bullet();
		bullet.x = self.x;
		bullet.y = self.y;
		var dx = target.x - self.x;
		var dy = target.y - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		bullet.direction.x = dx / distance;
		bullet.direction.y = dy / distance;
		return bullet;
	};
	self.findNearestEnemy = function (enemies) {
		var nearestDistance = Infinity;
		var nearestEnemy = null;
		for (var i = 0; i < enemies.length; i++) {
			var dx = enemies[i].x - self.x;
			var dy = enemies[i].y - self.y;
			var distance = Math.sqrt(dx * dx + dy * dy);
			if (distance < nearestDistance) {
				nearestDistance = distance;
				nearestEnemy = enemies[i];
			}
		}
		return nearestEnemy;
	};
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = XS.getAsset('enemy', 'Enemy character', .5, .5);
	enemyGraphics.rotation = -Math.PI / 2;
	self.addChild(enemyGraphics);
	self.speed = 2;
	self.move = function (hero) {
		var dx = hero.x - self.x;
		var dy = hero.y - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		self.x += self.speed * (dx / distance);
		self.y += self.speed * (dy / distance);
		self.rotation = Math.atan2(dy, dx);
	};
	self.shoot = function () {};
});
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = XS.getAsset('bullet', 'Bullet Graphics', .5, .5);
	self.addChild(bulletGraphics);
	self.speed = 10;
	self.direction = {
		x: 0,
		y: 0
	};
	self.move = function () {
		self.x += self.direction.x * self.speed;
		self.y += self.direction.y * self.speed;
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	XS.stageContainer.setBackgroundColor(0x004000);
	var score = 0;
	var heroAliveTime = 0;
	var targetIndicator = self.addChild(new TargetIndicator());
	var hero = self.addChild(new Hero());
	hero.x = 2048 / 2;
	hero.y = 2732 / 2;
	var scoreTxt = new Text2('0', {
		size: 150,
		fill: '#ffffff'
	});
	scoreTxt.anchor.set(.5, 0);
	XS.gui.topCenter.addChild(scoreTxt);
	stage.on('down', function (obj) {
		var pos = obj.event.getLocalPosition(self);
		hero.target.x = pos.x;
		hero.target.y = pos.y;
	});
	stage.on('move', function (obj) {
		var pos = obj.event.getLocalPosition(self);
		hero.target.x = pos.x;
		hero.target.y = pos.y;
	});
	var enemies = [];
	var enemyCount = 0;
	function spawnEnemy() {
		var enemy = self.addChild(new Enemy());
		var side = Math.floor(Math.random() * 4);
		switch (side) {
			case 0:
				enemy.x = Math.random() * 2048;
				enemy.y = -100;
				break;
			case 1:
				enemy.x = 2048 + 100;
				enemy.y = Math.random() * 2732;
				break;
			case 2:
				enemy.x = Math.random() * 2048;
				enemy.y = 2732 + 100;
				break;
			case 3:
				enemy.x = -100;
				enemy.y = Math.random() * 2732;
				break;
		}
		enemies.push(enemy);
		enemyCount++;
	}
	for (var i = 0; i < 10; i++) {
		spawnEnemy();
	}
	var bullets = [];
	XS.on('tick', function () {
		heroAliveTime++;
		if (XS.ticks % Math.max(10, 100 - Math.floor(heroAliveTime / 1000)) === 0) {
			spawnEnemy();
		}
		hero.move();
		var dx = hero.target.x - hero.x;
		var dy = hero.target.y - hero.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		if (hero.isMoving) {
			targetIndicator.visible = true;
			targetIndicator.x = hero.target.x;
			targetIndicator.y = hero.target.y;
		} else {
			targetIndicator.visible = false;
		}
		if (XS.ticks % 40 === 0 && !hero.isMoving) {
			var nearestEnemy = hero.findNearestEnemy(enemies);
			if (nearestEnemy) {
				var bullet = hero.shoot(nearestEnemy);
				bullets.push(bullet);
				self.addChild(bullet);
				hero.rotation = Math.atan2(nearestEnemy.y - hero.y, nearestEnemy.x - hero.x);
			}
		}
		for (var i = 0; i < enemies.length; i++) {
			enemies[i].move(hero);
			enemies[i].shoot();
			if (hero.intersects(enemies[i])) {
				XS.showGameOver();
				return;
			}
		}
		for (var i = 0; i < bullets.length; i++) {
			bullets[i].move();
			for (var j = 0; j < enemies.length; j++) {
				if (bullets[i].intersects(enemies[j])) {
					enemies[j].destroy();
					enemies.splice(j, 1);
					bullets[i].destroy();
					bullets.splice(i, 1);
					score++;
					scoreTxt.setText(score);
					break;
				}
			}
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -83,9 +83,9 @@
 	};
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
-	XS.stageContainer.setBackgroundColor(0x008000);
+	XS.stageContainer.setBackgroundColor(0x004000);
 	var score = 0;
 	var heroAliveTime = 0;
 	var targetIndicator = self.addChild(new TargetIndicator());
 	var hero = self.addChild(new Hero());