/**** 
* Plugins
****/ 
var tween = LK.import("@upit/tween.v1");

/**** 
* Classes
****/ 
// Hero class
var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroSprite = self.attachAsset('hero', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = heroSprite.width * 0.5;
	self.shootCooldown = 0; // ticks until next shot allowed
	// Called every tick
	self.update = function () {
		if (self.shootCooldown > 0) self.shootCooldown--;
	};
	// Shoot a bullet upwards
	self.shoot = function () {
		if (self.shootCooldown === 0) {
			var bullet = new HeroBullet();
			bullet.x = self.x;
			bullet.y = self.y - self.radius - bullet.height * 0.5;
			heroBullets.push(bullet);
			game.addChild(bullet);
			LK.getSound('heroShoot').play();
			self.shootCooldown = 12; // 12 ticks cooldown (~0.2s)
		}
	};
	return self;
});
// Hero bullet class
var HeroBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletSprite = self.attachAsset('heroBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = bulletSprite.width;
	self.height = bulletSprite.height;
	self.speed = -22;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Mutant enemy class
var Mutant = Container.expand(function () {
	var self = Container.call(this);
	var mutantSprite = self.attachAsset('mutant', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = mutantSprite.width * 0.5;
	self.speed = 3 + Math.random() * 2; // Vary speed a bit
	self.shootTimer = 60 + Math.floor(Math.random() * 60); // Randomize first shot
	self.hp = 2; // Mutants take 2 hits
	// Called every tick
	self.update = function () {
		self.y += self.speed;
		self.shootTimer--;
		if (self.shootTimer <= 0) {
			self.shoot();
			self.shootTimer = 90 + Math.floor(Math.random() * 60); // Next shot
		}
	};
	// Shoot a bullet downwards
	self.shoot = function () {
		var bullet = new MutantBullet();
		bullet.x = self.x;
		bullet.y = self.y + self.radius + bullet.height * 0.5;
		mutantBullets.push(bullet);
		game.addChild(bullet);
		LK.getSound('mutantShoot').play();
	};
	// Take damage
	self.hit = function () {
		self.hp--;
		LK.getSound('mutantHit').play();
		LK.effects.flashObject(self, 0xffffff, 150);
		if (self.hp <= 0) {
			self.destroy();
			return true;
		}
		return false;
	};
	return self;
});
// Mutant bullet class
var MutantBullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletSprite = self.attachAsset('mutantBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = bulletSprite.width;
	self.height = bulletSprite.height;
	self.speed = 14;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x181818
});

/**** 
* Game Code
****/ 
// Music
// Sound effects
// Mutant bullet: red ellipse
// Hero bullet: yellow box
// Mutant: green ellipse
// Hero: blue box
// Game variables
var hero;
var mutants = [];
var heroBullets = [];
var mutantBullets = [];
var lastHeroX = 0,
	lastHeroY = 0;
var score = 0;
var scoreTxt;
var wave = 1;
var spawnTimer = 0;
var gameOver = false;
// Score display
scoreTxt = new Text2('0', {
	size: 120,
	fill: "#fff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Start music
LK.playMusic('bgmusic');
// Create hero
hero = new Hero();
hero.x = 2048 / 2;
hero.y = 2732 - 350;
game.addChild(hero);
// Helper: spawn a wave of mutants
function spawnMutantWave() {
	// Only spawn a single mutant at a time
	if (mutants.length >= 1) return;
	var m = new Mutant();
	// Center mutant horizontally, randomize a bit
	m.x = 2048 / 2 + (Math.random() - 0.5) * 80;
	m.y = -100 - Math.random() * 200;
	mutants.push(m);
	game.addChild(m);
	wave++;
}
// Initial wave
spawnMutantWave();
// Touch/mouse drag controls removed -- hero is now controlled by tap-to-move
// Tap left/right half of screen to move hero horizontally by a fixed amount
game.down = function (x, y, obj) {
	var minX = hero.radius + 20;
	var maxX = 2048 - hero.radius - 20;
	// Only move horizontally, keep Y fixed
	var moveAmount = 220;
	if (x < 2048 / 2) {
		// Tap left half: move left
		hero.x = Math.max(minX, hero.x - moveAmount);
	} else {
		// Tap right half: move right
		hero.x = Math.min(maxX, hero.x + moveAmount);
	}
};
game.move = null;
game.up = null;
// Main game loop
game.update = function () {
	if (gameOver) return;
	// Hero update
	hero.update();
	// Hero auto-shoots every 10 ticks
	if (LK.ticks % 10 === 0) {
		hero.shoot();
	}
	// Mutant update
	for (var i = mutants.length - 1; i >= 0; i--) {
		var m = mutants[i];
		m.update();
		// Remove if off screen
		if (m.y > 2732 + 100) {
			m.destroy();
			mutants.splice(i, 1);
			continue;
		}
		// Mutant collides with hero (game over)
		if (m.intersects(hero)) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.getSound('heroHit').play();
			gameOver = true;
			LK.showGameOver();
			return;
		}
	}
	// Hero bullets update
	for (var i = heroBullets.length - 1; i >= 0; i--) {
		var b = heroBullets[i];
		b.update();
		// Remove if off screen
		if (b.y < -100) {
			b.destroy();
			heroBullets.splice(i, 1);
			continue;
		}
		// Check collision with mutants
		var hit = false;
		for (var j = mutants.length - 1; j >= 0; j--) {
			var m = mutants[j];
			if (b.intersects(m)) {
				b.destroy();
				heroBullets.splice(i, 1);
				if (m.hit()) {
					// Mutant destroyed
					m.destroy();
					mutants.splice(j, 1);
					score += 10;
					scoreTxt.setText(score);
				} else {
					score += 2;
					scoreTxt.setText(score);
				}
				hit = true;
				break;
			}
		}
		if (hit) continue;
	}
	// Mutant bullets update
	for (var i = mutantBullets.length - 1; i >= 0; i--) {
		var b = mutantBullets[i];
		b.update();
		// Remove if off screen
		if (b.y > 2732 + 100) {
			b.destroy();
			mutantBullets.splice(i, 1);
			continue;
		}
		// Check collision with hero
		if (b.intersects(hero)) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.getSound('heroHit').play();
			b.destroy();
			mutantBullets.splice(i, 1);
			gameOver = true;
			LK.showGameOver();
			return;
		}
	}
	// Spawn new wave if all mutants gone
	if (mutants.length === 0 && spawnTimer === 0) {
		spawnTimer = 40; // Wait 40 ticks before next wave
	}
	if (spawnTimer > 0) {
		spawnTimer--;
		if (spawnTimer === 0) {
			spawnMutantWave();
		}
	}
};
// Reset game state on restart
game.on('reset', function () {
	// Remove all objects
	for (var i = 0; i < mutants.length; i++) mutants[i].destroy();
	for (var i = 0; i < heroBullets.length; i++) heroBullets[i].destroy();
	for (var i = 0; i < mutantBullets.length; i++) mutantBullets[i].destroy();
	mutants = [];
	heroBullets = [];
	mutantBullets = [];
	score = 0;
	scoreTxt.setText(score);
	wave = 1;
	spawnTimer = 0;
	gameOver = false;
	hero.x = 2048 / 2;
	hero.y = 2732 - 350;
	spawnMutantWave();
	LK.playMusic('bgmusic');
});

===================================================================
--- original.js
+++ change.js
@@ -162,17 +162,21 @@
 }
 // Initial wave
 spawnMutantWave();
 // Touch/mouse drag controls removed -- hero is now controlled by tap-to-move
-// Tap anywhere to move hero to that location (clamped to game area)
+// Tap left/right half of screen to move hero horizontally by a fixed amount
 game.down = function (x, y, obj) {
-	// Clamp hero inside game area, avoid top 100px and bottom 100px
 	var minX = hero.radius + 20;
 	var maxX = 2048 - hero.radius - 20;
-	var minY = 120 + hero.radius;
-	var maxY = 2732 - hero.radius - 40;
-	hero.x = Math.max(minX, Math.min(maxX, x));
-	hero.y = Math.max(minY, Math.min(maxY, y));
+	// Only move horizontally, keep Y fixed
+	var moveAmount = 220;
+	if (x < 2048 / 2) {
+		// Tap left half: move left
+		hero.x = Math.max(minX, hero.x - moveAmount);
+	} else {
+		// Tap right half: move right
+		hero.x = Math.min(maxX, hero.x + moveAmount);
+	}
 };
 game.move = null;
 game.up = null;
 // Main game loop