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

/**** 
* Classes
****/ 
// Bullet class
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletSprite = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = bulletSprite.width / 2;
	self.vx = 0;
	self.vy = 0;
	self.lifetime = 60; // frames
	self.update = function () {
		self.x += self.vx;
		self.y += self.vy;
		self.lifetime--;
	};
	return self;
});
// Hero class
var Hero = Container.expand(function () {
	var self = Container.call(this);
	var heroSprite = self.attachAsset('hero', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Add gun sprite to hero's hand
	var gunSprite = self.attachAsset('gun', {
		anchorX: 0.2,
		// grip of gun
		anchorY: 0.5,
		width: heroSprite.width * 0.45,
		height: heroSprite.height * 0.22
	});
	gunSprite.x = heroSprite.width * 0.32; // offset to right hand
	gunSprite.y = 0;
	self.radius = heroSprite.width / 2;
	self.speed = 18; // pixels per move
	self.lastShotTick = 0;
	self.shootCooldown = 18; // frames between shots
	self.update = function () {};
	return self;
});
// Powerup class
var Powerup = Container.expand(function () {
	var self = Container.call(this);
	var powerupSprite = self.attachAsset('powerup', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = powerupSprite.width / 2;
	self.type = 'rapid'; // only one type for MVP
	self.update = function () {};
	return self;
});
// Zombie class
var Zombie = Container.expand(function () {
	var self = Container.call(this);
	// Default to normal zombie asset
	var zombieSprite = self.attachAsset('zombie', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.zombieSprite = zombieSprite;
	self.radius = zombieSprite.width / 2;
	self.baseSpeed = 3 + Math.random() * 2; // base speed, will be increased by wave
	self.speed = self.baseSpeed;
	self.target = null; // set to hero
	self.maxHp = 1;
	self.hp = 1;
	self.wave = 1;
	self.type = "normal"; // can be "normal", "fast", "tank", "crawler"
	self.setWave = function (wave) {
		self.wave = wave;
		// Remove old sprite if present
		if (self.zombieSprite && self.zombieSprite.parent) {
			self.removeChild(self.zombieSprite);
		}
		// Decide type
		var r = Math.random();
		if (wave >= 7 && r < 0.18) {
			// Crawler: slow, small, hard to hit
			self.type = "crawler";
			self.speed = 1.7 + 0.12 * wave;
			self.maxHp = 2 + Math.floor(wave / 3);
			self.hp = self.maxHp;
			self.zombieSprite = self.attachAsset('zombie_crawler', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.radius = self.zombieSprite.width / 2;
			self.zombieSprite.tint = 0x8e8e8e; // grayish
		} else if (wave >= 6 && r < 0.38) {
			// Tank zombie: slow but high HP
			self.type = "tank";
			self.speed = 2 + 0.15 * wave;
			self.maxHp = 3 + Math.floor(wave / 2);
			self.hp = self.maxHp;
			self.zombieSprite = self.attachAsset('zombie_tank', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.radius = self.zombieSprite.width / 2;
			self.zombieSprite.tint = 0x6e4e2e; // brownish
		} else if (wave >= 3 && r < 0.63) {
			// Fast zombie: high speed, low HP
			self.type = "fast";
			self.speed = 5 + 0.4 * wave;
			self.maxHp = 1;
			self.hp = 1;
			self.zombieSprite = self.attachAsset('zombie_fast', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.radius = self.zombieSprite.width / 2;
			self.zombieSprite.tint = 0x7cf442; // bright green
		} else {
			// Normal zombie
			self.type = "normal";
			self.speed = self.baseSpeed + (wave - 1) * 0.5;
			self.maxHp = 1 + Math.floor(wave / 4);
			self.hp = self.maxHp;
			self.zombieSprite = self.attachAsset('zombie', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.radius = self.zombieSprite.width / 2;
			self.zombieSprite.tint = 0x7bbf3f; // normal green
		}
	};
	self.update = function () {
		if (!self.target) return;
		var dx = self.target.x - self.x;
		var dy = self.target.y - self.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		if (dist > 0) {
			self.x += self.speed * dx / dist;
			self.y += self.speed * dy / dist;
		}
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// new gun asset
// Music
// Sound effects
// Powerup: blue ellipse
// Bullet: yellow box
// Zombie: green ellipse
// Hero: red box
// Game area
var GAME_W = 2048;
var GAME_H = 2732;
// State
var hero = null;
var zombies = [];
var bullets = [];
var powerups = [];
var dragNode = null;
var lastIntersecting = false;
var score = 0;
var highScore = storage.highScore || 0;
var wave = 1;
var ticksSinceStart = 0;
var zombieSpawnTick = 0;
var zombieSpawnInterval = 90; // frames
var rapidFireTicks = 0;
// --- MENU STATE ---
var menuActive = true;
var menuOverlay = new Container();
var menuBg = LK.getAsset('hero', {
	anchorX: 0.5,
	anchorY: 0.5,
	width: 900,
	height: 900,
	color: 0x222222
});
menuBg.alpha = 0.92;
menuBg.x = GAME_W / 2;
menuBg.y = GAME_H / 2;
menuOverlay.addChild(menuBg);
var menuTitle = new Text2('Zombie Swarm Survival', {
	size: 120,
	fill: "#fff"
});
menuTitle.anchor.set(0.5, 0.5);
menuTitle.x = GAME_W / 2;
menuTitle.y = GAME_H / 2 - 250;
menuOverlay.addChild(menuTitle);
var menuDesc = new Text2('Survive as long as you can!\nDrag to move. Tap to shoot.', {
	size: 60,
	fill: "#fff"
});
menuDesc.anchor.set(0.5, 0.5);
menuDesc.x = GAME_W / 2;
menuDesc.y = GAME_H / 2 - 80;
menuOverlay.addChild(menuDesc);
var menuBest = new Text2('Best: ' + highScore, {
	size: 70,
	fill: 0xF7E733
});
menuBest.anchor.set(0.5, 0.5);
menuBest.x = GAME_W / 2;
menuBest.y = GAME_H / 2 + 80;
menuOverlay.addChild(menuBest);
var menuBtn = new Text2('START', {
	size: 110,
	fill: 0x3FA34D
});
menuBtn.anchor.set(0.5, 0.5);
menuBtn.x = GAME_W / 2;
menuBtn.y = GAME_H / 2 + 250;
menuOverlay.addChild(menuBtn);
game.addChild(menuOverlay);
// Score text
var scoreTxt = new Text2('0', {
	size: 120,
	fill: "#fff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// High score text
var highScoreTxt = new Text2('Best: ' + highScore, {
	size: 60,
	fill: "#fff"
});
highScoreTxt.anchor.set(0.5, 0);
highScoreTxt.y = 120;
LK.gui.top.addChild(highScoreTxt);
// Powerup text
var powerupTxt = new Text2('', {
	size: 70,
	fill: 0x3B7DD8
});
powerupTxt.anchor.set(0.5, 0);
powerupTxt.y = 200;
LK.gui.top.addChild(powerupTxt);
// Only spawn hero after menu
function startGame() {
	menuActive = false;
	menuOverlay.visible = false;
	// Reset state
	score = 0;
	wave = 1;
	ticksSinceStart = 0;
	zombieSpawnTick = 0;
	zombieSpawnInterval = 90;
	rapidFireTicks = 0;
	scoreTxt.setText('0');
	highScoreTxt.setText('Best: ' + highScore);
	powerupTxt.setText('');
	// Remove all zombies, bullets, powerups
	for (var i = 0; i < zombies.length; i++) zombies[i].destroy();
	for (var i = 0; i < bullets.length; i++) bullets[i].destroy();
	for (var i = 0; i < powerups.length; i++) powerups[i].destroy();
	zombies = [];
	bullets = [];
	powerups = [];
	// Spawn hero in center
	if (hero) hero.destroy();
	hero = new Hero();
	hero.x = GAME_W / 2;
	hero.y = GAME_H / 2;
	game.addChild(hero);
}
// Menu tap handler
menuOverlay.down = function (x, y, obj) {
	// Only start if tap is on START button area
	var dx = x - menuBtn.x;
	var dy = y - menuBtn.y;
	if (dx * dx + dy * dy < 40000) {
		// radius ~200px
		startGame();
	}
};
// Helper: spawn zombie at random edge
function spawnZombie() {
	var z = new Zombie();
	// Pick edge: 0=top,1=bottom,2=left,3=right
	var edge = Math.floor(Math.random() * 4);
	var margin = 80;
	if (edge === 0) {
		// top
		z.x = margin + Math.random() * (GAME_W - 2 * margin);
		z.y = -z.radius;
	} else if (edge === 1) {
		// bottom
		z.x = margin + Math.random() * (GAME_W - 2 * margin);
		z.y = GAME_H + z.radius;
	} else if (edge === 2) {
		// left
		z.x = -z.radius;
		z.y = margin + Math.random() * (GAME_H - 2 * margin);
	} else {
		// right
		z.x = GAME_W + z.radius;
		z.y = margin + Math.random() * (GAME_H - 2 * margin);
	}
	// Set wave and type
	if (typeof z.setWave === "function") {
		z.setWave(wave);
	}
	z.target = hero;
	zombies.push(z);
	game.addChild(z);
}
// Helper: spawn powerup
function spawnPowerup() {
	var p = new Powerup();
	p.x = 200 + Math.random() * (GAME_W - 400);
	p.y = 300 + Math.random() * (GAME_H - 600);
	powerups.push(p);
	game.addChild(p);
}
// Helper: shoot bullet towards (tx,ty)
function shootBullet(tx, ty) {
	if (LK.ticks - hero.lastShotTick < (rapidFireTicks > 0 ? 6 : hero.shootCooldown)) return;
	var b = new Bullet();
	b.x = hero.x;
	b.y = hero.y;
	var dx = tx - hero.x;
	var dy = ty - hero.y;
	var dist = Math.sqrt(dx * dx + dy * dy);
	var speed = 38;
	b.vx = speed * dx / dist;
	b.vy = speed * dy / dist;
	bullets.push(b);
	game.addChild(b);
	hero.lastShotTick = LK.ticks;
	LK.getSound('shoot').play();
}
// Helper: distance between two objects
function dist2(a, b) {
	var dx = a.x - b.x;
	var dy = a.y - b.y;
	return Math.sqrt(dx * dx + dy * dy);
}
// Dragging
function handleMove(x, y, obj) {
	if (menuActive) return;
	if (dragNode) {
		// Clamp hero inside game area
		var r = hero.radius;
		dragNode.x = Math.max(r, Math.min(GAME_W - r, x));
		dragNode.y = Math.max(r, Math.min(GAME_H - r, y));
	}
}
game.move = handleMove;
game.down = function (x, y, obj) {
	if (menuActive) return;
	// Only drag if touch is on hero
	if (dist2({
		x: x,
		y: y
	}, hero) <= hero.radius * 1.2) {
		dragNode = hero;
	}
};
game.up = function (x, y, obj) {
	if (menuActive) return;
	dragNode = null;
	// Shoot bullet towards release point if not dragging
	if (dist2({
		x: x,
		y: y
	}, hero) > hero.radius * 1.2) {
		shootBullet(x, y);
	}
};
// Main update loop
game.update = function () {
	if (menuActive) {
		// Block all gameplay updates while menu is active
		return;
	}
	ticksSinceStart++;
	// Increase wave every 900 ticks (~15s)
	if (ticksSinceStart % 900 === 0) {
		wave++;
		if (zombieSpawnInterval > 30) zombieSpawnInterval -= 8;
	}
	// Spawn zombies
	if (LK.ticks - zombieSpawnTick > zombieSpawnInterval) {
		// More zombies per spawn as wave increases
		var zombiesToSpawn = 1 + Math.floor(wave / 4);
		for (var n = 0; n < zombiesToSpawn; n++) {
			spawnZombie();
		}
		zombieSpawnTick = LK.ticks;
	}
	// Maybe spawn powerup
	if (powerups.length === 0 && Math.random() < 0.002) {
		spawnPowerup();
	}
	// Update hero (nothing for now)
	hero.update();
	// Update zombies
	for (var i = zombies.length - 1; i >= 0; i--) {
		var z = zombies[i];
		z.update();
		// Check collision with hero
		if (dist2(z, hero) < z.radius + hero.radius - 10) {
			LK.effects.flashScreen(0xff0000, 1000);
			if (score > highScore) {
				storage.highScore = score;
			}
			LK.showGameOver();
			// Show menu again after game over
			menuActive = true;
			menuOverlay.visible = true;
			menuBest.setText('Best: ' + (score > highScore ? score : highScore));
			return;
		}
	}
	// Update bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		var b = bullets[i];
		b.update();
		// Remove if out of bounds or expired
		if (b.x < -100 || b.x > GAME_W + 100 || b.y < -100 || b.y > GAME_H + 100 || b.lifetime <= 0) {
			b.destroy();
			bullets.splice(i, 1);
			continue;
		}
		// Check collision with zombies
		for (var j = zombies.length - 1; j >= 0; j--) {
			var z = zombies[j];
			if (dist2(b, z) < b.radius + z.radius - 10) {
				// Damage zombie
				if (typeof z.hp === "number") {
					z.hp--;
					LK.effects.flashObject(z, 0xffffff, 120);
					if (z.hp <= 0) {
						LK.getSound('zombie_die').play();
						score++;
						scoreTxt.setText(score);
						if (score > highScore) {
							highScore = score;
							highScoreTxt.setText('Best: ' + highScore);
							storage.highScore = highScore;
						}
						z.destroy();
						zombies.splice(j, 1);
					}
				} else {
					// fallback: destroy if no hp
					LK.getSound('zombie_die').play();
					score++;
					scoreTxt.setText(score);
					if (score > highScore) {
						highScore = score;
						highScoreTxt.setText('Best: ' + highScore);
						storage.highScore = highScore;
					}
					z.destroy();
					zombies.splice(j, 1);
				}
				b.destroy();
				bullets.splice(i, 1);
				break;
			}
		}
	}
	// Update powerups
	for (var i = powerups.length - 1; i >= 0; i--) {
		var p = powerups[i];
		// Check collision with hero
		if (dist2(p, hero) < p.radius + hero.radius - 10) {
			LK.getSound('powerup').play();
			rapidFireTicks = 360; // 6 seconds
			powerupTxt.setText('Rapid Fire!');
			LK.effects.flashObject(hero, 0x3b7dd8, 400);
			p.destroy();
			powerups.splice(i, 1);
		}
	}
	// Powerup timer
	if (rapidFireTicks > 0) {
		rapidFireTicks--;
		if (rapidFireTicks === 0) {
			powerupTxt.setText('');
		}
	}
	// Update powerup text alpha for effect
	if (rapidFireTicks > 0) {
		powerupTxt.alpha = 0.7 + 0.3 * Math.sin(LK.ticks / 6);
	} else {
		powerupTxt.alpha = 1;
	}
};
// Start music
LK.playMusic('bgmusic', {
	fade: {
		start: 0,
		end: 0.7,
		duration: 1200
	}
});

===================================================================
--- original.js
+++ change.js
@@ -63,44 +63,78 @@
 });
 // Zombie class
 var Zombie = Container.expand(function () {
 	var self = Container.call(this);
+	// Default to normal zombie asset
 	var zombieSprite = self.attachAsset('zombie', {
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
+	self.zombieSprite = zombieSprite;
 	self.radius = zombieSprite.width / 2;
 	self.baseSpeed = 3 + Math.random() * 2; // base speed, will be increased by wave
 	self.speed = self.baseSpeed;
 	self.target = null; // set to hero
 	self.maxHp = 1;
 	self.hp = 1;
 	self.wave = 1;
-	self.type = "normal"; // can be "normal", "fast", "tank"
+	self.type = "normal"; // can be "normal", "fast", "tank", "crawler"
 	self.setWave = function (wave) {
 		self.wave = wave;
-		// Increase speed and HP based on wave and type
-		if (wave >= 6 && Math.random() < 0.25) {
+		// Remove old sprite if present
+		if (self.zombieSprite && self.zombieSprite.parent) {
+			self.removeChild(self.zombieSprite);
+		}
+		// Decide type
+		var r = Math.random();
+		if (wave >= 7 && r < 0.18) {
+			// Crawler: slow, small, hard to hit
+			self.type = "crawler";
+			self.speed = 1.7 + 0.12 * wave;
+			self.maxHp = 2 + Math.floor(wave / 3);
+			self.hp = self.maxHp;
+			self.zombieSprite = self.attachAsset('zombie_crawler', {
+				anchorX: 0.5,
+				anchorY: 0.5
+			});
+			self.radius = self.zombieSprite.width / 2;
+			self.zombieSprite.tint = 0x8e8e8e; // grayish
+		} else if (wave >= 6 && r < 0.38) {
 			// Tank zombie: slow but high HP
 			self.type = "tank";
 			self.speed = 2 + 0.15 * wave;
 			self.maxHp = 3 + Math.floor(wave / 2);
 			self.hp = self.maxHp;
-			zombieSprite.tint = 0x6e4e2e; // brownish
-		} else if (wave >= 3 && Math.random() < 0.25) {
+			self.zombieSprite = self.attachAsset('zombie_tank', {
+				anchorX: 0.5,
+				anchorY: 0.5
+			});
+			self.radius = self.zombieSprite.width / 2;
+			self.zombieSprite.tint = 0x6e4e2e; // brownish
+		} else if (wave >= 3 && r < 0.63) {
 			// Fast zombie: high speed, low HP
 			self.type = "fast";
 			self.speed = 5 + 0.4 * wave;
 			self.maxHp = 1;
 			self.hp = 1;
-			zombieSprite.tint = 0x7cf442; // bright green
+			self.zombieSprite = self.attachAsset('zombie_fast', {
+				anchorX: 0.5,
+				anchorY: 0.5
+			});
+			self.radius = self.zombieSprite.width / 2;
+			self.zombieSprite.tint = 0x7cf442; // bright green
 		} else {
 			// Normal zombie
 			self.type = "normal";
 			self.speed = self.baseSpeed + (wave - 1) * 0.5;
 			self.maxHp = 1 + Math.floor(wave / 4);
 			self.hp = self.maxHp;
-			zombieSprite.tint = 0x7bbf3f; // normal green
+			self.zombieSprite = self.attachAsset('zombie', {
+				anchorX: 0.5,
+				anchorY: 0.5
+			});
+			self.radius = self.zombieSprite.width / 2;
+			self.zombieSprite.tint = 0x7bbf3f; // normal green
 		}
 	};
 	self.update = function () {
 		if (!self.target) return;
@@ -364,9 +398,13 @@
 		if (zombieSpawnInterval > 30) zombieSpawnInterval -= 8;
 	}
 	// Spawn zombies
 	if (LK.ticks - zombieSpawnTick > zombieSpawnInterval) {
-		spawnZombie();
+		// More zombies per spawn as wave increases
+		var zombiesToSpawn = 1 + Math.floor(wave / 4);
+		for (var n = 0; n < zombiesToSpawn; n++) {
+			spawnZombie();
+		}
 		zombieSpawnTick = LK.ticks;
 	}
 	// Maybe spawn powerup
 	if (powerups.length === 0 && Math.random() < 0.002) {