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

/**** 
* Classes
****/ 
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.speed = 8;
	self.damage = player ? player.damage : 20;
	self.direction = {
		x: 0,
		y: 0
	};
	self.update = function () {
		self.x += self.direction.x * self.speed;
		self.y += self.direction.y * self.speed;
		if (self.x < -50 || self.x > 2098 || self.y < -50 || self.y > 2782) {
			self.shouldRemove = true;
		}
	};
	return self;
});
var Player = Container.expand(function () {
	var self = Container.call(this);
	var playerGraphics = self.attachAsset('player', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.health = 100;
	self.maxHealth = 100;
	self.damage = 20;
	self.fireRate = 30; // Lower = faster
	self.speed = 4;
	self.lastShot = 0;
	self.takeDamage = function (amount) {
		self.health -= amount;
		if (self.health <= 0) {
			self.health = 0;
			LK.showGameOver();
		} else {
			LK.effects.flashObject(self, 0xff0000, 300);
			LK.getSound('playerHit').play();
		}
	};
	self.heal = function (amount) {
		self.health = Math.min(self.maxHealth, self.health + amount);
	};
	return self;
});
var XPOrb = Container.expand(function () {
	var self = Container.call(this);
	var orbGraphics = self.attachAsset('xpOrb', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.value = 10;
	self.collectDistance = 30;
	self.update = function () {
		var dx = player.x - self.x;
		var dy = player.y - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		if (distance < self.collectDistance) {
			self.x += dx / distance * 6;
			self.y += dy / distance * 6;
			if (distance < 20) {
				currentXP += self.value;
				checkLevelUp();
				self.shouldRemove = true;
			}
		}
	};
	return self;
});
var Zombie = Container.expand(function (type) {
	var self = Container.call(this);
	self.type = type || 'normal';
	self.speed = 1;
	self.health = 40;
	self.damage = 25;
	self.xpValue = 10;
	var assetId = 'zombie';
	if (self.type === 'fast') {
		assetId = 'fastZombie';
		self.speed = 2.5;
		self.health = 25;
		self.damage = 20;
		self.xpValue = 15;
	} else if (self.type === 'strong') {
		assetId = 'strongZombie';
		self.speed = 0.8;
		self.health = 80;
		self.damage = 40;
		self.xpValue = 25;
	}
	var zombieGraphics = self.attachAsset(assetId, {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.takeDamage = function (amount) {
		self.health -= amount;
		LK.effects.flashObject(self, 0xffffff, 200);
		if (self.health <= 0) {
			self.isDead = true;
			LK.getSound('zombieHit').play();
		}
	};
	self.update = function () {
		if (self.isDead) return;
		var dx = player.x - self.x;
		var dy = player.y - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		if (distance > 5) {
			self.x += dx / distance * self.speed;
			self.y += dy / distance * self.speed;
		} else {
			// Attack player
			if (!self.lastAttack || LK.ticks - self.lastAttack > 60) {
				player.takeDamage(self.damage);
				self.lastAttack = LK.ticks;
			}
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x2C3E50
});

/**** 
* Game Code
****/ 
var player;
var zombies = [];
var bullets = [];
var xpOrbs = [];
var currentXP = 0;
var currentLevel = 1;
var xpToNextLevel = 100;
var waveNumber = 1;
var zombiesSpawned = 0;
var zombiesInWave = 10;
var spawnTimer = 0;
var spawnRate = 120; // frames between spawns
var isShowingUpgrade = false;
var upgrades = [];
// UI Elements
var healthBar, xpBar, levelText, waveText, scoreText;
function initializeUI() {
	// Health bar background
	var healthBg = LK.getAsset('healthBg', {
		width: 400,
		height: 20,
		color: 0x800000,
		shape: 'box'
	});
	healthBg.x = 100;
	healthBg.y = 100;
	LK.gui.topLeft.addChild(healthBg);
	// Health bar
	healthBar = LK.getAsset('healthBar', {
		width: 400,
		height: 20,
		color: 0x00ff00,
		shape: 'box'
	});
	healthBar.x = 100;
	healthBar.y = 100;
	LK.gui.topLeft.addChild(healthBar);
	// XP bar background
	var xpBg = LK.getAsset('xpBg', {
		width: 400,
		height: 15,
		color: 0x404040,
		shape: 'box'
	});
	xpBg.x = 100;
	xpBg.y = 130;
	LK.gui.topLeft.addChild(xpBg);
	// XP bar
	xpBar = LK.getAsset('xpBar', {
		width: 400,
		height: 15,
		color: 0x00FFFF,
		shape: 'box'
	});
	xpBar.x = 100;
	xpBar.y = 130;
	LK.gui.topLeft.addChild(xpBar);
	// Level text
	levelText = new Text2('Level: 1', {
		size: 40,
		fill: '#ffffff'
	});
	levelText.anchor.set(0, 0);
	levelText.x = 100;
	levelText.y = 50;
	LK.gui.topLeft.addChild(levelText);
	// Wave text
	waveText = new Text2('Wave: 1', {
		size: 30,
		fill: '#ffffff'
	});
	waveText.anchor.set(0.5, 0);
	waveText.x = 1024;
	waveText.y = 50;
	LK.gui.top.addChild(waveText);
	// Score text
	scoreText = new Text2('Score: 0', {
		size: 30,
		fill: '#ffffff'
	});
	scoreText.anchor.set(1, 0);
	scoreText.x = 1948;
	scoreText.y = 50;
	LK.gui.topRight.addChild(scoreText);
}
function updateUI() {
	if (healthBar) {
		var healthPercent = player.health / player.maxHealth;
		healthBar.width = 400 * healthPercent;
	}
	if (xpBar) {
		var xpPercent = currentXP / xpToNextLevel;
		xpBar.width = 400 * Math.min(xpPercent, 1);
	}
	if (levelText) {
		levelText.setText('Level: ' + currentLevel);
	}
	if (waveText) {
		waveText.setText('Wave: ' + waveNumber);
	}
	if (scoreText) {
		scoreText.setText('Score: ' + LK.getScore());
	}
}
function checkLevelUp() {
	if (currentXP >= xpToNextLevel) {
		currentXP -= xpToNextLevel;
		currentLevel++;
		xpToNextLevel = Math.floor(xpToNextLevel * 1.5);
		LK.getSound('levelUp').play();
		showUpgradeScreen();
	}
}
function showUpgradeScreen() {
	isShowingUpgrade = true;
	// Create upgrade options
	var availableUpgrades = [{
		name: 'Damage +20%',
		apply: function apply() {
			player.damage = Math.floor(player.damage * 1.2);
		}
	}, {
		name: 'Fire Rate +25%',
		apply: function apply() {
			player.fireRate = Math.max(5, Math.floor(player.fireRate * 0.75));
		}
	}, {
		name: 'Max Health +50',
		apply: function apply() {
			player.maxHealth += 50;
			player.heal(50);
		}
	}, {
		name: 'Speed +20%',
		apply: function apply() {
			player.speed = player.speed * 1.2;
		}
	}, {
		name: 'Health Regen',
		apply: function apply() {
			player.hasRegen = true;
		}
	}];
	// Create upgrade UI (simplified - just pick first 3)
	var upgradeOptions = [];
	for (var i = 0; i < 3 && i < availableUpgrades.length; i++) {
		upgradeOptions.push(availableUpgrades[i]);
	}
	// Create upgrade buttons
	var upgradeContainer = new Container();
	upgradeContainer.x = 1024;
	upgradeContainer.y = 1366;
	var bgPanel = LK.getAsset('upgradePanel', {
		width: 800,
		height: 600,
		color: 0x1a1a1a,
		shape: 'box'
	});
	upgradeContainer.addChild(bgPanel);
	var titleText = new Text2('LEVEL UP! Choose an upgrade:', {
		size: 50,
		fill: '#00FFFF'
	});
	titleText.anchor.set(0.5, 0.5);
	titleText.y = -200;
	upgradeContainer.addChild(titleText);
	for (var i = 0; i < upgradeOptions.length; i++) {
		var option = upgradeOptions[i];
		var button = LK.getAsset('upgradeButton' + i, {
			width: 600,
			height: 100,
			color: 0x0066CC,
			shape: 'box'
		});
		button.y = -50 + i * 120;
		button.upgradeFunction = option.apply;
		var buttonText = new Text2(option.name, {
			size: 40,
			fill: '#ffffff'
		});
		buttonText.anchor.set(0.5, 0.5);
		button.addChild(buttonText);
		button.down = function (x, y, obj) {
			this.upgradeFunction();
			game.removeChild(upgradeContainer);
			isShowingUpgrade = false;
		};
		upgradeContainer.addChild(button);
	}
	game.addChild(upgradeContainer);
}
function spawnZombie() {
	var type = 'normal';
	var rand = Math.random();
	if (waveNumber > 3 && rand < 0.3) type = 'fast';
	if (waveNumber > 5 && rand < 0.2) type = 'strong';
	var zombie = new Zombie(type);
	// Spawn from edges
	var edge = Math.floor(Math.random() * 4);
	if (edge === 0) {
		// top
		zombie.x = Math.random() * 2048;
		zombie.y = -50;
	} else if (edge === 1) {
		// right
		zombie.x = 2098;
		zombie.y = Math.random() * 2732;
	} else if (edge === 2) {
		// bottom
		zombie.x = Math.random() * 2048;
		zombie.y = 2782;
	} else {
		// left
		zombie.x = -50;
		zombie.y = Math.random() * 2732;
	}
	zombies.push(zombie);
	game.addChild(zombie);
	zombiesSpawned++;
}
function startNextWave() {
	waveNumber++;
	zombiesSpawned = 0;
	zombiesInWave = Math.floor(10 + waveNumber * 2.5);
	spawnRate = Math.max(30, 120 - waveNumber * 5);
}
// Initialize player
player = new Player();
player.x = 1024;
player.y = 1366;
game.addChild(player);
initializeUI();
var targetX = player.x;
var targetY = player.y;
game.move = function (x, y, obj) {
	if (isShowingUpgrade) return;
	targetX = x;
	targetY = y;
};
game.down = function (x, y, obj) {
	if (isShowingUpgrade) return;
	targetX = x;
	targetY = y;
};
game.update = function () {
	if (isShowingUpgrade) return;
	// Move player towards target
	var dx = targetX - player.x;
	var dy = targetY - player.y;
	var distance = Math.sqrt(dx * dx + dy * dy);
	if (distance > 5) {
		player.x += dx / distance * player.speed;
		player.y += dy / distance * player.speed;
	}
	// Keep player in bounds
	player.x = Math.max(40, Math.min(2008, player.x));
	player.y = Math.max(40, Math.min(2692, player.y));
	// Player health regen
	if (player.hasRegen && LK.ticks % 120 === 0) {
		player.heal(5);
	}
	// Auto-shoot at nearest zombie
	if (zombies.length > 0 && LK.ticks - player.lastShot >= player.fireRate) {
		var nearestZombie = null;
		var nearestDistance = Infinity;
		for (var i = 0; i < zombies.length; i++) {
			if (zombies[i].isDead) continue;
			var zdx = zombies[i].x - player.x;
			var zdy = zombies[i].y - player.y;
			var zdist = Math.sqrt(zdx * zdx + zdy * zdy);
			if (zdist < nearestDistance) {
				nearestDistance = zdist;
				nearestZombie = zombies[i];
			}
		}
		if (nearestZombie && nearestDistance < 400) {
			var bullet = new Bullet();
			bullet.x = player.x;
			bullet.y = player.y;
			var bdx = nearestZombie.x - player.x;
			var bdy = nearestZombie.y - player.y;
			var bdist = Math.sqrt(bdx * bdx + bdy * bdy);
			bullet.direction.x = bdx / bdist;
			bullet.direction.y = bdy / bdist;
			bullets.push(bullet);
			game.addChild(bullet);
			player.lastShot = LK.ticks;
			LK.getSound('shoot').play();
		}
	}
	// Update bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		var bullet = bullets[i];
		if (bullet.shouldRemove) {
			bullet.destroy();
			bullets.splice(i, 1);
			continue;
		}
		// Check bullet-zombie collisions
		for (var j = zombies.length - 1; j >= 0; j--) {
			var zombie = zombies[j];
			if (zombie.isDead) continue;
			if (bullet.intersects(zombie)) {
				zombie.takeDamage(bullet.damage);
				bullet.shouldRemove = true;
				if (zombie.isDead) {
					LK.setScore(LK.getScore() + zombie.xpValue);
					// Create XP orb
					var xpOrb = new XPOrb();
					xpOrb.x = zombie.x;
					xpOrb.y = zombie.y;
					xpOrb.value = zombie.xpValue;
					xpOrbs.push(xpOrb);
					game.addChild(xpOrb);
				}
				break;
			}
		}
	}
	// Update zombies
	for (var i = zombies.length - 1; i >= 0; i--) {
		var zombie = zombies[i];
		if (zombie.isDead) {
			zombie.destroy();
			zombies.splice(i, 1);
		}
	}
	// Update XP orbs
	for (var i = xpOrbs.length - 1; i >= 0; i--) {
		var orb = xpOrbs[i];
		if (orb.shouldRemove) {
			orb.destroy();
			xpOrbs.splice(i, 1);
		}
	}
	// Spawn zombies
	spawnTimer++;
	if (spawnTimer >= spawnRate && zombiesSpawned < zombiesInWave) {
		spawnZombie();
		spawnTimer = 0;
	}
	// Check if wave is complete
	if (zombiesSpawned >= zombiesInWave && zombies.length === 0) {
		startNextWave();
	}
	updateUI();
};

===================================================================
--- original.js
+++ change.js
@@ -322,9 +322,9 @@
 		});
 		buttonText.anchor.set(0.5, 0.5);
 		button.addChild(buttonText);
 		button.down = function (x, y, obj) {
-			obj.upgradeFunction();
+			this.upgradeFunction();
 			game.removeChild(upgradeContainer);
 			isShowingUpgrade = false;
 		};
 		upgradeContainer.addChild(button);