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

/**** 
* Classes
****/ 
// Alien enemy
var Alien = Container.expand(function () {
	var self = Container.call(this);
	var alien = self.attachAsset('alien', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = alien.width;
	self.height = alien.height;
	self.direction = 1; // 1: right, -1: left
	self.speed = 3;
	self.shootChance = 0.002; // chance per frame to shoot
	self.row = 0;
	self.col = 0;
	self.alive = true;
	self.update = function () {
		// Movement handled by game for all aliens together
		// Randomly shoot
		if (Math.random() < self.shootChance && self.alive) {
			self.shoot();
		}
	};
	self.shoot = function () {
		var bullet = new AlienBullet();
		bullet.x = self.x;
		bullet.y = self.y + self.height / 2 + bullet.height / 2;
		alienBullets.push(bullet);
		game.addChild(bullet);
		LK.getSound('alienShoot').play();
	};
	self.hit = function () {
		if (!self.alive) {
			return;
		}
		self.alive = false;
		tween(self, {
			alpha: 0
		}, {
			duration: 200,
			onFinish: function onFinish() {
				self.destroy();
			}
		});
		LK.getSound('explosion').play();
		LK.setScore(LK.getScore() + 10);
		scoreTxt.setText(LK.getScore());
	};
	return self;
});
// Alien bullet
var AlienBullet = Container.expand(function () {
	var self = Container.call(this);
	var bullet = self.attachAsset('alienBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = bullet.width;
	self.height = bullet.height;
	self.speed = 18;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player bullet
var PlayerBullet = Container.expand(function () {
	var self = Container.call(this);
	var bullet = self.attachAsset('playerBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = bullet.width;
	self.height = bullet.height;
	self.speed = -32;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player spaceship
var PlayerShip = Container.expand(function () {
	var self = Container.call(this);
	var ship = self.attachAsset('playerShip', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = ship.width;
	self.height = ship.height;
	self.canShoot = true;
	self.shootCooldown = 18; // frames
	self.cooldownTimer = 0;
	self.lives = 3;
	self.invincible = false;
	self.invincibleTimer = 0;
	self.update = function () {
		if (!self.canShoot) {
			self.cooldownTimer--;
			if (self.cooldownTimer <= 0) {
				self.canShoot = true;
			}
		}
		if (self.invincible) {
			self.invincibleTimer--;
			if (self.invincibleTimer <= 0) {
				self.invincible = false;
				ship.alpha = 1;
			}
		}
	};
	self.shoot = function () {
		if (self.canShoot) {
			var bullet = new PlayerBullet();
			bullet.x = self.x;
			bullet.y = self.y - self.height / 2 - bullet.height / 2;
			playerBullets.push(bullet);
			game.addChild(bullet);
			LK.getSound('shoot').play();
			self.canShoot = false;
			self.cooldownTimer = self.shootCooldown;
		}
	};
	self.hit = function () {
		if (self.invincible) {
			return;
		}
		self.lives--;
		self.invincible = true;
		self.invincibleTimer = 60;
		ship.alpha = 0.4;
		LK.effects.flashObject(self, 0xff0000, 400);
		if (self.lives <= 0) {
			LK.effects.flashScreen(0xff0000, 1000);
			LK.showGameOver();
		}
	};
	self.collectPowerup = function () {
		self.lives++;
		LK.getSound('powerup').play();
	};
	return self;
});
// Power-up
var Powerup = Container.expand(function () {
	var self = Container.call(this);
	var p = self.attachAsset('powerup', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = p.width;
	self.height = p.height;
	self.speed = 10;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x000010
});

/**** 
* Game Code
****/ 
// Music
// Sound effects
// Power-up
// Alien bullet
// Player bullet
// Alien enemy
// Spaceship (player)
// Play music
LK.playMusic('spaceMusic');
// Score display
var scoreTxt = new Text2('0', {
	size: 120,
	fill: 0xFFFFFF
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Lives display
var livesTxt = new Text2('♥♥♥', {
	size: 90,
	fill: 0xFF4D4D
});
livesTxt.anchor.set(1, 0);
livesTxt.x = -40;
LK.gui.topRight.addChild(livesTxt);
// Game variables
var player;
var playerBullets = [];
var alienBullets = [];
var aliens = [];
var powerups = [];
var alienRows = 4;
var alienCols = 8;
var alienSpacingX = 180;
var alienSpacingY = 140;
var alienStartY = 300;
var alienMoveDir = 1; // 1: right, -1: left
var alienMoveDown = false;
var alienMoveSpeed = 18;
var alienMoveTimer = 0;
var alienMoveInterval = 30; // frames
var wave = 1;
var dragNode = null;
var lastTouchX = 0;
// Initialize player
player = new PlayerShip();
player.x = 2048 / 2;
player.y = 2732 - 180;
game.addChild(player);
// Initialize aliens
function spawnAliens() {
	for (var row = 0; row < alienRows; row++) {
		for (var col = 0; col < alienCols; col++) {
			var alien = new Alien();
			alien.x = 2048 / 2 - (alienCols - 1) * alienSpacingX / 2 + col * alienSpacingX;
			alien.y = alienStartY + row * alienSpacingY;
			alien.row = row;
			alien.col = col;
			aliens.push(alien);
			game.addChild(alien);
		}
	}
}
spawnAliens();
// Powerup spawn timer
var powerupTimer = 0;
var powerupInterval = 600; // frames
// Touch/move controls
game.down = function (x, y, obj) {
	// Move ship to X position if touch/click in bottom 1/3
	if (y > 2732 * 0.7) {
		player.x = x;
		// Clamp to screen
		if (player.x < player.width / 2) {
			player.x = player.width / 2;
		}
		if (player.x > 2048 - player.width / 2) {
			player.x = 2048 - player.width / 2;
		}
	}
};
// No dragNode needed for this control scheme
game.move = function (x, y, obj) {
	// Move ship to X position if touch/cursor in bottom 1/3
	if (y > 2732 * 0.7) {
		player.x = x;
		// Clamp to screen
		if (player.x < player.width / 2) {
			player.x = player.width / 2;
		}
		if (player.x > 2048 - player.width / 2) {
			player.x = 2048 - player.width / 2;
		}
	}
};
// Tap to shoot if not in bottom 1/3
game.up = function (x, y, obj) {
	if (y <= 2732 * 0.7) {
		player.shoot();
	}
};
// Main update loop
game.update = function () {
	// Update player
	player.update();
	// Update lives display
	var livesStr = '';
	for (var i = 0; i < player.lives; i++) {
		livesStr += '♥';
	}
	livesTxt.setText(livesStr);
	// Update player bullets
	for (var i = playerBullets.length - 1; i >= 0; i--) {
		var b = playerBullets[i];
		b.update();
		// Remove if off screen
		if (b.y < -b.height) {
			b.destroy();
			playerBullets.splice(i, 1);
			continue;
		}
		// Check collision with aliens
		for (var j = 0; j < aliens.length; j++) {
			var a = aliens[j];
			if (a.alive && b.intersects(a)) {
				a.hit();
				b.destroy();
				playerBullets.splice(i, 1);
				break;
			}
		}
	}
	// Update alien bullets
	for (var i = alienBullets.length - 1; i >= 0; i--) {
		var ab = alienBullets[i];
		ab.update();
		// Remove if off screen
		if (ab.y > 2732 + ab.height) {
			ab.destroy();
			alienBullets.splice(i, 1);
			continue;
		}
		// Check collision with player
		if (ab.intersects(player) && !player.invincible) {
			ab.destroy();
			alienBullets.splice(i, 1);
			player.hit();
			continue;
		}
	}
	// Update aliens
	var leftMost = 2048,
		rightMost = 0,
		bottomMost = 0;
	for (var i = 0; i < aliens.length; i++) {
		var a = aliens[i];
		if (!a.alive) {
			continue;
		}
		a.update();
		if (a.x < leftMost) {
			leftMost = a.x;
		}
		if (a.x > rightMost) {
			rightMost = a.x;
		}
		if (a.y > bottomMost) {
			bottomMost = a.y;
		}
	}
	// Aliens movement (all together)
	alienMoveTimer++;
	if (alienMoveTimer >= alienMoveInterval) {
		alienMoveTimer = 0;
		var moveX = alienMoveSpeed * alienMoveDir;
		var needReverse = false;
		// Check if any alien hits edge
		for (var i = 0; i < aliens.length; i++) {
			var a = aliens[i];
			if (!a.alive) {
				continue;
			}
			var nextX = a.x + moveX;
			if (nextX < a.width / 2 + 40 || nextX > 2048 - a.width / 2 - 40) {
				needReverse = true;
				break;
			}
		}
		if (needReverse) {
			alienMoveDir *= -1;
			for (var i = 0; i < aliens.length; i++) {
				var a = aliens[i];
				if (!a.alive) {
					continue;
				}
				a.y += 80;
				// If any alien reaches bottom, game over
				if (a.y + a.height / 2 >= player.y - player.height / 2) {
					LK.effects.flashScreen(0xff0000, 1000);
					LK.showGameOver();
					return;
				}
			}
		} else {
			for (var i = 0; i < aliens.length; i++) {
				var a = aliens[i];
				if (!a.alive) {
					continue;
				}
				a.x += moveX;
			}
		}
	}
	// Remove dead aliens from array
	for (var i = aliens.length - 1; i >= 0; i--) {
		if (!aliens[i].alive && aliens[i].alpha === 0) {
			aliens.splice(i, 1);
		}
	}
	// If all aliens dead, next wave
	if (aliens.length === 0) {
		wave++;
		alienRows = Math.min(6, 3 + wave);
		alienCols = Math.min(10, 6 + wave);
		alienMoveSpeed = 18 + wave * 2;
		alienMoveInterval = Math.max(10, 30 - wave * 2);
		spawnAliens();
		// Powerup drop
		var p = new Powerup();
		p.x = 2048 / 2;
		p.y = 200;
		powerups.push(p);
		game.addChild(p);
	}
	// Powerup spawn
	powerupTimer++;
	if (powerupTimer >= powerupInterval) {
		powerupTimer = 0;
		var p = new Powerup();
		p.x = 200 + Math.random() * (2048 - 400);
		p.y = 200;
		powerups.push(p);
		game.addChild(p);
	}
	// Update powerups
	for (var i = powerups.length - 1; i >= 0; i--) {
		var p = powerups[i];
		p.update();
		if (p.y > 2732 + p.height) {
			p.destroy();
			powerups.splice(i, 1);
			continue;
		}
		if (p.intersects(player)) {
			player.collectPowerup();
			p.destroy();
			powerups.splice(i, 1);
			continue;
		}
	}
};

===================================================================
--- original.js
+++ change.js
@@ -240,41 +240,38 @@
 var powerupTimer = 0;
 var powerupInterval = 600; // frames
 // Touch/move controls
 game.down = function (x, y, obj) {
-	// Only allow dragging from bottom 1/3 of screen
+	// Move ship to X position if touch/click in bottom 1/3
 	if (y > 2732 * 0.7) {
-		dragNode = player;
-		lastTouchX = x;
+		player.x = x;
+		// Clamp to screen
+		if (player.x < player.width / 2) {
+			player.x = player.width / 2;
+		}
+		if (player.x > 2048 - player.width / 2) {
+			player.x = 2048 - player.width / 2;
+		}
 	}
 };
-game.up = function (x, y, obj) {
-	dragNode = null;
-};
+// No dragNode needed for this control scheme
 game.move = function (x, y, obj) {
-	if (dragNode === player) {
-		// Only move horizontally
-		var dx = x - lastTouchX;
-		player.x += dx;
+	// Move ship to X position if touch/cursor in bottom 1/3
+	if (y > 2732 * 0.7) {
+		player.x = x;
 		// Clamp to screen
 		if (player.x < player.width / 2) {
 			player.x = player.width / 2;
 		}
 		if (player.x > 2048 - player.width / 2) {
 			player.x = 2048 - player.width / 2;
 		}
-		lastTouchX = x;
 	}
 };
-// Tap to shoot
+// Tap to shoot if not in bottom 1/3
 game.up = function (x, y, obj) {
-	if (dragNode === player) {
-		dragNode = null;
-	} else {
-		// If tap in bottom 1/3, move; else, shoot
-		if (y <= 2732 * 0.7) {
-			player.shoot();
-		}
+	if (y <= 2732 * 0.7) {
+		player.shoot();
 	}
 };
 // Main update loop
 game.update = function () {