===================================================================
--- original.js
+++ change.js
@@ -1,6 +1,438 @@
-/****
+/**** 
+* 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: 0x000000
-});
\ No newline at end of file
+	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) {
+	// Only allow dragging from bottom 1/3 of screen
+	if (y > 2732 * 0.7) {
+		dragNode = player;
+		lastTouchX = x;
+	}
+};
+game.up = function (x, y, obj) {
+	dragNode = null;
+};
+game.move = function (x, y, obj) {
+	if (dragNode === player) {
+		// Only move horizontally
+		var dx = x - lastTouchX;
+		player.x += dx;
+		// 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
+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();
+		}
+	}
+};
+// 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;
+		}
+	}
+};
\ No newline at end of file