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

/**** 
* Classes
****/ 
// Enemy bullet
var EnemyBullet = Container.expand(function () {
	var self = Container.call(this);
	var bullet = self.attachAsset('enemyBullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 18;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Enemy ship
var EnemyShip = Container.expand(function () {
	var self = Container.call(this);
	var ship = self.attachAsset('enemyShip', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = ship.width;
	self.height = ship.height;
	self.speed = 6;
	self.shootCooldown = 0;
	self.update = function () {
		self.y += self.speed;
		if (self.shootCooldown > 0) {
			self.shootCooldown--;
		}
	};
	return self;
});
// Explosion effect (MVP: fade out and destroy)
var Explosion = Container.expand(function () {
	var self = Container.call(this);
	var exp = self.attachAsset('explosion', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	exp.alpha = 1;
	tween(exp, {
		alpha: 0
	}, {
		duration: 400,
		easing: tween.linear,
		onFinish: function onFinish() {
			self.destroy();
		}
	});
	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.speed = -28;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player ship
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.lives = 3;
	self.invincible = false;
	self.invincibleTicks = 0;
	self.update = function () {
		if (self.invincible) {
			self.invincibleTicks--;
			ship.alpha = self.invincibleTicks % 10 < 5 ? 0.4 : 1;
			if (self.invincibleTicks <= 0) {
				self.invincible = false;
				ship.alpha = 1;
			}
		}
	};
	// Flash for damage
	self.flash = function () {
		LK.effects.flashObject(self, 0xffffff, 400);
	};
	return self;
});
// PowerUp class
var PowerUp = Container.expand(function () {
	var self = Container.call(this);
	// Types: 'speed', 'double', 'invincible', 'rapid', 'shield', 'score'
	self.type = 'speed';
	self.duration = 600; // 10 seconds at 60fps
	// Icon color by type
	var colorMap = {
		speed: 0x00ffff,
		"double": 0xffd700,
		invincible: 0xffffff,
		rapid: 0xff00ff,
		shield: 0x00ff00,
		score: 0xff6600
	};
	var icon = self.attachAsset('boosts', {
		anchorX: 0.5,
		anchorY: 0.5,
		scaleX: 3,
		scaleY: 3,
		color: colorMap[self.type] || 0xffffff
	});
	self.width = icon.width;
	self.height = icon.height;
	self.speed = 8;
	self.setType = function (type) {
		self.type = type;
		icon.color = colorMap[type] || 0xffffff;
	};
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Starfield background star
var Star = Container.expand(function () {
	var self = Container.call(this);
	var star = self.attachAsset('star', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 0;
	self.update = function () {
		self.y += self.speed;
		if (self.y > 2732 + 10) {
			self.y = -10;
			self.x = 50 + Math.random() * (2048 - 100);
			self.speed = 2 + Math.random() * 4;
		}
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// Music (placeholder, not played in MVP)
// Sounds
// Explosion: green box (for MVP, will flash and fade)
// Star: white ellipse
// Enemy bullet: orange ellipse
// Player bullet: yellow ellipse
// Enemy ship: red box
// Player ship: blue box
// Starfield
var stars = [];
for (var i = 0; i < 60; i++) {
	var star = new Star();
	star.x = 50 + Math.random() * (2048 - 100);
	star.y = Math.random() * 2732;
	star.speed = 2 + Math.random() * 4;
	stars.push(star);
	game.addChild(star);
}
// Player
var player = new PlayerShip();
player.x = 2048 / 2;
player.y = 2732 - 300;
game.addChild(player);
// Player bullets
var playerBullets = [];
// Enemies
var enemies = [];
var enemyBullets = [];
// Explosions
var explosions = [];
// Power-ups
var powerUp = null;
var powerUpActive = false;
var powerUpType = null;
var powerUpTicks = 0;
var powerUpIcon = null;
var powerUpTimerTxt = null;
var nextPowerUpTicks = 300; // 5s to 8s after last
// Score and lives
var score = 0;
var scoreTxt = new Text2('0', {
	size: 120,
	fill: 0xFFFFFF
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
var livesTxt = new Text2('♥♥♥', {
	size: 90,
	fill: 0xFF6666
});
livesTxt.anchor.set(1, 0);
LK.gui.topRight.addChild(livesTxt);
// Power-up UI
powerUpIcon = new Container();
var iconAsset = LK.getAsset('boosts-ui', {
	anchorX: 0.5,
	anchorY: 0,
	scaleX: 2,
	scaleY: 2,
	color: 0xffffff
});
powerUpIcon.addChild(iconAsset);
powerUpIcon.visible = false;
powerUpIcon.x = 120;
powerUpIcon.y = 20;
LK.gui.top.addChild(powerUpIcon);
powerUpTimerTxt = new Text2('', {
	size: 60,
	fill: 0xffffff
});
powerUpTimerTxt.anchor.set(0, 0);
powerUpTimerTxt.x = 60;
powerUpTimerTxt.y = 0;
powerUpIcon.addChild(powerUpTimerTxt);
// Dragging
var dragNode = null;
// Enemy spawn control
var enemySpawnTicks = 0;
var enemySpawnInterval = 60; // ticks (1s)
var enemySpeed = 6;
var minEnemySpawnInterval = 24; // fastest spawn (0.4s)
var maxEnemySpeed = 18;
// Player shoot control
var playerShootCooldown = 0;
var playerShootInterval = 12; // ticks (0.2s)
// Game state
var gameOver = false;
// Move handler
function handleMove(x, y, obj) {
	if (dragNode && !gameOver) {
		// Clamp to game area (leave 60px margin)
		var halfW = player.width / 2;
		var halfH = player.height / 2;
		// Power-up: speed
		var speedMult = powerUpActive && powerUpType === 'speed' ? 2 : 1;
		// Move player faster if speed boost
		var px = player.x + (x - player.x) * 0.2 * speedMult;
		var py = player.y + (y - player.y) * 0.2 * speedMult;
		var nx = Math.max(halfW + 60, Math.min(2048 - halfW - 60, px));
		var ny = Math.max(halfH + 120, Math.min(2732 - halfH - 60, py));
		player.x = nx;
		player.y = ny;
	}
}
game.move = handleMove;
game.down = function (x, y, obj) {
	if (!gameOver) {
		dragNode = player;
		handleMove(x, y, obj);
	}
};
game.up = function (x, y, obj) {
	dragNode = null;
};
// Update function
game.update = function () {
	if (gameOver) {
		return;
	}
	// Update starfield
	for (var i = 0; i < stars.length; i++) {
		stars[i].update();
	}
	// Update player
	player.update();
	// Power-up spawn logic
	if (!powerUp && !powerUpActive) {
		nextPowerUpTicks--;
		if (nextPowerUpTicks <= 0) {
			powerUp = new PowerUp();
			// Random type
			var types = ['speed', 'double', 'invincible', 'rapid', 'score'];
			var t = types[Math.floor(Math.random() * types.length)];
			powerUp.setType(t);
			powerUp.x = 100 + Math.random() * (2048 - 200);
			powerUp.y = -60;
			game.addChild(powerUp);
		}
	}
	// Power-up update
	if (powerUp) {
		powerUp.update();
		// Remove if off screen
		if (powerUp.y > 2732 + 60) {
			powerUp.destroy();
			powerUp = null;
			nextPowerUpTicks = 300 + Math.floor(Math.random() * 180); // 5-8s
		}
		// Pickup
		if (powerUp && powerUp.intersects(player)) {
			// Activate effect
			powerUpActive = true;
			powerUpType = powerUp.type;
			powerUpTicks = 600; // 10s
			// UI
			powerUpIcon.visible = true;
			var colorMap = {
				speed: 0x00ffff,
				"double": 0xffd700,
				invincible: 0xffffff,
				rapid: 0xff00ff,
				shield: 0x00ff00,
				score: 0xff6600
			};
			powerUpIcon.children[0].color = colorMap[powerUpType] || 0xffffff;
			powerUpTimerTxt.setText('10.0');
			// Sound/Effect
			LK.getSound('shoot').play();
			// Remove from game
			powerUp.destroy();
			powerUp = null;
		}
	}
	// Power-up effect timer
	if (powerUpActive) {
		powerUpTicks--;
		// UI update
		powerUpTimerTxt.setText((powerUpTicks / 60).toFixed(1));
		if (powerUpTicks <= 0) {
			// Expire
			powerUpActive = false;
			powerUpType = null;
			powerUpIcon.visible = false;
			nextPowerUpTicks = 300 + Math.floor(Math.random() * 180);
			// Sound/Effect
			LK.getSound('explosion').play();
		}
	}
	// Player shooting
	if (playerShootCooldown > 0) {
		playerShootCooldown--;
	}
	if (dragNode && playerShootCooldown <= 0) {
		// Power-up: double shot or rapid
		if (powerUpActive && powerUpType === 'double') {
			// Two bullets
			for (var i = -1; i <= 1; i += 2) {
				var pb = new PlayerBullet();
				pb.x = player.x + i * 40;
				pb.y = player.y - player.height / 2 - 10;
				playerBullets.push(pb);
				game.addChild(pb);
			}
		} else {
			var pb = new PlayerBullet();
			pb.x = player.x;
			pb.y = player.y - player.height / 2 - 10;
			playerBullets.push(pb);
			game.addChild(pb);
		}
		// Rapid fire
		if (powerUpActive && powerUpType === 'rapid') {
			playerShootCooldown = Math.floor(playerShootInterval / 2);
		} else {
			playerShootCooldown = playerShootInterval;
		}
		LK.getSound('shoot').play();
	}
	// 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 < -40) {
			b.destroy();
			playerBullets.splice(i, 1);
			continue;
		}
		// Check collision with enemies
		for (var j = enemies.length - 1; j >= 0; j--) {
			var e = enemies[j];
			if (b.intersects(e)) {
				// Explosion
				var exp = new Explosion();
				exp.x = e.x;
				exp.y = e.y;
				explosions.push(exp);
				game.addChild(exp);
				LK.getSound('explosion').play();
				// Remove enemy and bullet
				e.destroy();
				enemies.splice(j, 1);
				b.destroy();
				playerBullets.splice(i, 1);
				// Score
				score++;
				scoreTxt.setText(score);
				// Difficulty up
				if (score % 10 === 0 && enemySpawnInterval > minEnemySpawnInterval) {
					enemySpawnInterval -= 6;
					if (enemySpawnInterval < minEnemySpawnInterval) {
						enemySpawnInterval = minEnemySpawnInterval;
					}
				}
				if (score % 15 === 0 && enemySpeed < maxEnemySpeed) {
					enemySpeed += 2;
					if (enemySpeed > maxEnemySpeed) {
						enemySpeed = maxEnemySpeed;
					}
				}
				break;
			}
		}
	}
	// Spawn enemies
	enemySpawnTicks++;
	if (enemySpawnTicks >= enemySpawnInterval) {
		enemySpawnTicks = 0;
		var e = new EnemyShip();
		e.x = 100 + Math.random() * (2048 - 200);
		e.y = -80;
		e.speed = enemySpeed;
		e.shootCooldown = 30 + Math.floor(Math.random() * 40);
		enemies.push(e);
		game.addChild(e);
	}
	// Update enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		var e = enemies[i];
		e.update();
		// Remove if off screen
		if (e.y > 2732 + 100) {
			e.destroy();
			enemies.splice(i, 1);
			continue;
		}
		// Enemy shooting
		if (e.shootCooldown <= 0) {
			var eb = new EnemyBullet();
			eb.x = e.x;
			eb.y = e.y + e.height / 2 + 10;
			enemyBullets.push(eb);
			game.addChild(eb);
			e.shootCooldown = 60 + Math.floor(Math.random() * 40);
			LK.getSound('enemyShoot').play();
		}
	}
	// Update enemy bullets
	for (var i = enemyBullets.length - 1; i >= 0; i--) {
		var eb = enemyBullets[i];
		eb.update();
		// Remove if off screen
		if (eb.y > 2732 + 40) {
			eb.destroy();
			enemyBullets.splice(i, 1);
			continue;
		}
		// Check collision with player
		if (!player.invincible && !(powerUpActive && powerUpType === 'invincible') && eb.intersects(player)) {
			eb.destroy();
			enemyBullets.splice(i, 1);
			// Damage player
			player.lives--;
			player.invincible = true;
			player.invincibleTicks = 60;
			player.flash();
			// Update lives display
			var livesStr = '';
			for (var l = 0; l < player.lives; l++) {
				livesStr += '♥';
			}
			livesTxt.setText(livesStr);
			// Explosion
			var exp = new Explosion();
			exp.x = player.x;
			exp.y = player.y;
			explosions.push(exp);
			game.addChild(exp);
			LK.getSound('explosion').play();
			// Game over
			if (player.lives <= 0) {
				gameOver = true;
				LK.effects.flashScreen(0xff0000, 1200);
				LK.showGameOver();
				return;
			}
		}
	}
	// Update explosions (auto-destroyed by tween)
	// No need to update, but clean up destroyed ones
	for (var i = explosions.length - 1; i >= 0; i--) {
		if (explosions[i].destroyed) {
			explosions.splice(i, 1);
		}
	}
};
// Play background music
LK.playMusic('background_music2', {
	fade: {
		start: 0,
		end: 1,
		duration: 1000
	}
});

===================================================================
--- original.js
+++ change.js
@@ -160,17 +160,17 @@
 
 /**** 
 * Game Code
 ****/ 
-// Starfield
-// Player ship: blue box
-// Enemy ship: red box
-// Player bullet: yellow ellipse
-// Enemy bullet: orange ellipse
-// Star: white ellipse
-// Explosion: green box (for MVP, will flash and fade)
-// Sounds
 // Music (placeholder, not played in MVP)
+// Sounds
+// Explosion: green box (for MVP, will flash and fade)
+// Star: white ellipse
+// Enemy bullet: orange ellipse
+// Player bullet: yellow ellipse
+// Enemy ship: red box
+// Player ship: blue box
+// Starfield
 var stars = [];
 for (var i = 0; i < 60; i++) {
 	var star = new Star();
 	star.x = 50 + Math.random() * (2048 - 100);
@@ -214,11 +214,11 @@
 livesTxt.anchor.set(1, 0);
 LK.gui.topRight.addChild(livesTxt);
 // Power-up UI
 powerUpIcon = new Container();
-var iconAsset = LK.getAsset('star', {
+var iconAsset = LK.getAsset('boosts-ui', {
 	anchorX: 0.5,
-	anchorY: 0.5,
+	anchorY: 0,
 	scaleX: 2,
 	scaleY: 2,
 	color: 0xffffff
 });