/**** 
* Classes
****/ 
var Bullet = Container.expand(function (damage) {
	var self = Container.call(this);
	var bulletGraphics = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.vx = 0;
	self.vy = 0;
	self.damage = damage || 10;
	self.lifetime = 60; // Bullets disappear after 1 second
	self.update = function () {
		// Move bullet
		self.x += self.vx;
		self.y += self.vy;
		// Decrease lifetime
		self.lifetime--;
		return self.lifetime <= 0;
	};
	return self;
});
var CooldownIndicator = Container.expand(function () {
	var self = Container.call(this);
	var bgCircle = self.attachAsset('cooldownIndicator', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0.5
	});
	var fillCircle = new Container();
	var fillGraphics = fillCircle.attachAsset('manualTarget', {
		anchorX: 0.5,
		anchorY: 0.5,
		width: 70,
		height: 70
	});
	self.addChild(fillCircle);
	var cooldownText = new Text2("READY", {
		size: 20,
		fill: 0xffffff
	});
	cooldownText.anchor.set(0.5);
	self.addChild(cooldownText);
	self.update = function (cooldown, maxCooldown) {
		if (cooldown <= 0) {
			fillCircle.alpha = 1;
			cooldownText.text = "READY";
		} else {
			fillCircle.alpha = 0.3;
			cooldownText.text = Math.ceil(cooldown / 60) + "s";
		}
	};
	return self;
});
var Explosion = Container.expand(function () {
	var self = Container.call(this);
	var explosionGraphics = self.attachAsset('explosion', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.lifetime = 15;
	self.scale.set(0.2);
	self.update = function () {
		self.lifetime--;
		self.scale.set(1 - self.lifetime / 20);
		self.alpha = self.lifetime / 15;
		return self.lifetime <= 0;
	};
	return self;
});
var ManualTarget = Container.expand(function () {
	var self = Container.call(this);
	var targetGraphics = self.attachAsset('manualTarget', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.lifetime = 15;
	self.alpha = 0.5;
	self.update = function () {
		self.lifetime--;
		self.alpha = self.lifetime / 15;
		self.rotation += 0.1;
		return self.lifetime <= 0;
	};
	return self;
});
var StatusBar = Container.expand(function () {
	var self = Container.call(this);
	// Top bar background
	var barBg = self.attachAsset('topBar', {
		anchorX: 0.5,
		anchorY: 0
	});
	// Wave indicator
	var waveDisplay = new Container();
	var waveIndicator = waveDisplay.attachAsset('waveIndicator', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0.8
	});
	var waveText = new Text2("WAVE 1", {
		size: 40,
		fill: 0xffffff
	});
	waveText.anchor.set(0.5);
	waveDisplay.addChild(waveText);
	waveDisplay.x = 0;
	waveDisplay.y = 60;
	self.addChild(waveDisplay);
	// Stats display
	var statsContainer = new Container();
	var statsBg = statsContainer.attachAsset('statDisplay', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0.7
	});
	var killsText = new Text2("Kills: 0", {
		size: 30,
		fill: 0xffffff
	});
	killsText.anchor.set(0.5);
	killsText.y = -20;
	statsContainer.addChild(killsText);
	var scoreText = new Text2("Score: 0", {
		size: 30,
		fill: 0xffffff
	});
	scoreText.anchor.set(0.5);
	scoreText.y = 20;
	statsContainer.addChild(scoreText);
	statsContainer.x = 500;
	statsContainer.y = 60;
	self.addChild(statsContainer);
	self.updateWave = function (waveNum) {
		waveText.text = "WAVE " + waveNum;
	};
	self.updateStats = function (kills, score) {
		killsText.text = "Kills: " + kills;
		scoreText.text = "Score: " + score;
	};
	return self;
});
var Tower = Container.expand(function () {
	var self = Container.call(this);
	// Tower base (doesn't rotate)
	var base = self.attachAsset('towerBase', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Tower turret (rotates to aim)
	var turret = new Container();
	var turretGraphics = turret.attachAsset('tower', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.addChild(turret);
	// Tower stats
	self.health = 100;
	self.maxHealth = 100;
	self.damage = 10;
	self.fireRate = 60; // frames between shots
	self.fireTimer = 0;
	self.range = 800;
	self.upgradeLevel = {
		damage: 1,
		fireRate: 1,
		range: 1,
		health: 1
	};
	// Health bar - moved above tower for better visibility
	var healthBarContainer = new Container();
	var healthBarBg = healthBarContainer.attachAsset('healthBarBg', {
		anchorX: 0.5,
		anchorY: 0.5,
		width: 200
	});
	var healthBarFill = new Container();
	var healthBarGraphics = healthBarFill.attachAsset('healthBar', {
		anchorX: 0,
		anchorY: 0.5,
		width: 200
	});
	healthBarContainer.addChild(healthBarFill);
	healthBarContainer.y = -150;
	self.addChild(healthBarContainer);
	// Add health text
	var healthText = new Text2("", {
		size: 24,
		fill: 0xffffff
	});
	healthText.anchor.set(0.5);
	healthText.y = -150;
	self.addChild(healthText);
	// Methods
	self.update = function () {
		// Decrease fire timer
		if (self.fireTimer > 0) {
			self.fireTimer--;
		}
		// Update health bar
		healthBarFill.scale.x = self.health / self.maxHealth;
		healthText.text = self.health + "/" + self.maxHealth;
		// Find target if none currently
		var target = null;
		var closestDist = self.range;
		for (var i = 0; i < zombies.length; i++) {
			var zombie = zombies[i];
			var dx = zombie.x - self.x;
			var dy = zombie.y - self.y;
			var dist = Math.sqrt(dx * dx + dy * dy);
			if (dist < closestDist) {
				closestDist = dist;
				target = zombie;
			}
		}
		// Aim at target
		if (target) {
			var angle = Math.atan2(target.y - self.y, target.x - self.x);
			turret.rotation = angle;
			// Fire if ready
			if (self.fireTimer <= 0) {
				var bullet = new Bullet(self.damage);
				bullet.x = self.x;
				bullet.y = self.y;
				bullet.rotation = angle;
				bullet.vx = Math.cos(angle) * 15;
				bullet.vy = Math.sin(angle) * 15;
				game.addChild(bullet);
				bullets.push(bullet);
				self.fireTimer = self.fireRate;
				LK.getSound('shoot').play();
			}
		}
	};
	self.manualShoot = function (x, y) {
		var angle = Math.atan2(y - self.y, x - self.x);
		turret.rotation = angle;
		var bullet = new Bullet(self.damage * 2); // Manual shots do double damage
		bullet.x = self.x;
		bullet.y = self.y;
		bullet.rotation = angle;
		bullet.vx = Math.cos(angle) * 15;
		bullet.vy = Math.sin(angle) * 15;
		game.addChild(bullet);
		bullets.push(bullet);
		LK.getSound('shoot').play();
	};
	self.takeDamage = function (amount) {
		self.health -= amount;
		// Flash the tower when hit
		LK.effects.flashObject(self, 0xff0000, 300);
		LK.getSound('towerHit').play();
		if (self.health <= 0) {
			return true; // Tower destroyed
		}
		return false;
	};
	self.upgrade = function (stat) {
		var maxLevel = 10; // Maximum upgrade level
		if (self.upgradeLevel[stat] >= maxLevel) {
			return 0; // Already at max level
		}
		var cost = 0;
		switch (stat) {
			case 'damage':
				cost = 50 * self.upgradeLevel.damage;
				self.damage += 5;
				self.upgradeLevel.damage++;
				break;
			case 'fireRate':
				cost = 75 * self.upgradeLevel.fireRate;
				self.fireRate = Math.max(10, self.fireRate - 5); // Min fire rate of 10 frames
				self.upgradeLevel.fireRate++;
				break;
			case 'range':
				cost = 100 * self.upgradeLevel.range;
				self.range += 50;
				self.upgradeLevel.range++;
				break;
			case 'health':
				cost = 60 * self.upgradeLevel.health;
				self.maxHealth += 25;
				self.health += 25;
				self.upgradeLevel.health++;
				break;
		}
		// Flash effect on upgrade
		LK.effects.flashObject(self, 0x00ff00, 500);
		LK.getSound('upgrade').play();
		return cost;
	};
	return self;
});
var UpgradePanel = Container.expand(function () {
	var self = Container.call(this);
	// Panel background
	var panelBg = self.attachAsset('upgradePanel', {
		anchorX: 0.5,
		anchorY: 1
	});
	// Create upgrade buttons
	self.createUpgradeButton = function (label, position) {
		var button = new Container();
		var buttonGraphics = button.attachAsset('upgradeButton', {
			anchorX: 0.5,
			anchorY: 0.5
		});
		var buttonText = new Text2(label, {
			size: 30,
			fill: 0xffffff
		});
		buttonText.anchor.set(0.5);
		buttonText.y = -20;
		button.addChild(buttonText);
		var costText = new Text2("", {
			size: 24,
			fill: 0xffcc00
		});
		costText.anchor.set(0.5);
		costText.y = 20;
		button.addChild(costText);
		button.x = -670 + position * 450;
		button.y = -200;
		self.addChild(button);
		return {
			container: button,
			costText: costText,
			bounds: {
				x: button.x - 225,
				y: button.y - 50,
				width: 450,
				height: 100
			}
		};
	};
	var buttons = {
		damage: self.createUpgradeButton("Damage", 0),
		fireRate: self.createUpgradeButton("Fire Rate", 1),
		range: self.createUpgradeButton("Range", 2),
		health: self.createUpgradeButton("Health", 3)
	};
	// Gold display
	var goldContainer = new Container();
	var goldIcon = goldContainer.attachAsset('goldIcon', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var goldText = new Text2("0", {
		size: 40,
		fill: 0xffcc00
	});
	goldText.x = 50;
	goldText.y = 0;
	goldText.anchor.set(0, 0.5);
	goldContainer.addChild(goldText);
	goldContainer.x = -160;
	goldContainer.y = -300;
	self.addChild(goldContainer);
	// Upgrade costs 
	var upgradeCosts = {
		damage: function damage() {
			return 50 * tower.upgradeLevel.damage;
		},
		fireRate: function fireRate() {
			return 75 * tower.upgradeLevel.fireRate;
		},
		range: function range() {
			return 100 * tower.upgradeLevel.range;
		},
		health: function health() {
			return 60 * tower.upgradeLevel.health;
		}
	};
	self.createUpgradeButton = function (label, position) {
		var button = new Container();
		var buttonGraphics = button.attachAsset('upgradeButton', {
			anchorX: 0.5,
			anchorY: 0.5
		});
		var buttonText = new Text2(label, {
			size: 30,
			fill: 0xffffff
		});
		buttonText.anchor.set(0.5);
		buttonText.y = -20;
		button.addChild(buttonText);
		var costText = new Text2("", {
			size: 24,
			fill: 0xffcc00
		});
		costText.anchor.set(0.5);
		costText.y = 20;
		button.addChild(costText);
		button.x = -670 + position * 450;
		button.y = -200;
		self.addChild(button);
		return {
			container: button,
			costText: costText,
			bounds: {
				x: button.x - 225,
				y: button.y - 50,
				width: 450,
				height: 100
			}
		};
	};
	self.updateGold = function (amount) {
		goldText.text = amount;
	};
	self.update = function () {
		// Update cost displays
		buttons.damage.costText.text = upgradeCosts.damage() + " Gold";
		buttons.fireRate.costText.text = upgradeCosts.fireRate() + " Gold";
		buttons.range.costText.text = upgradeCosts.range() + " Gold";
		buttons.health.costText.text = upgradeCosts.health() + " Gold";
		// Change button colors based on affordability
		self.updateButtonAppearance(buttons.damage, upgradeCosts.damage() <= gold);
		self.updateButtonAppearance(buttons.fireRate, upgradeCosts.fireRate() <= gold);
		self.updateButtonAppearance(buttons.range, upgradeCosts.range() <= gold);
		self.updateButtonAppearance(buttons.health, upgradeCosts.health() <= gold);
	};
	self.updateButtonAppearance = function (button, canAfford) {
		var color = canAfford ? 0x3366ff : 0x444444;
		button.container.children[0].tint = color;
	};
	self.checkUpgradeClick = function (x, y, currentGold) {
		var relativeX = x - self.x;
		var relativeY = y - self.y;
		// Check each button
		if (self.isPointInButton(relativeX, relativeY, buttons.damage.bounds)) {
			var cost = upgradeCosts.damage();
			if (currentGold >= cost) {
				return tower.upgrade('damage');
			}
		} else if (self.isPointInButton(relativeX, relativeY, buttons.fireRate.bounds)) {
			var cost = upgradeCosts.fireRate();
			if (currentGold >= cost) {
				return tower.upgrade('fireRate');
			}
		} else if (self.isPointInButton(relativeX, relativeY, buttons.range.bounds)) {
			var cost = upgradeCosts.range();
			if (currentGold >= cost) {
				return tower.upgrade('range');
			}
		} else if (self.isPointInButton(relativeX, relativeY, buttons.health.bounds)) {
			var cost = upgradeCosts.health();
			if (currentGold >= cost) {
				return tower.upgrade('health');
			}
		}
		return 0; // No upgrade performed
	};
	self.isPointInButton = function (x, y, bounds) {
		return x >= bounds.x && x <= bounds.x + bounds.width && y >= bounds.y && y <= bounds.y + bounds.height;
	};
	return self;
});
var Zombie = Container.expand(function (level) {
	var self = Container.call(this);
	level = level || 1;
	// Scale color from green to red based on level
	var colorValue = Math.min(255, 50 + level * 20);
	var zombieColor = colorValue << 16 | 255 - colorValue << 8;
	var zombieGraphics = self.attachAsset('zombie', {
		anchorX: 0.5,
		anchorY: 0.5,
		color: zombieColor
	});
	// Zombie stats
	self.health = 20 + level * 10;
	self.maxHealth = self.health;
	self.damage = 5 + level;
	self.speed = 1 + level * 0.1;
	self.value = 10 + level * 5; // Gold value when killed
	// Health bar
	var healthBarContainer = new Container();
	var healthBarBg = healthBarContainer.attachAsset('healthBarBg', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var healthBarFill = new Container();
	var healthBarGraphics = healthBarFill.attachAsset('healthBar', {
		anchorX: 0,
		anchorY: 0.5
	});
	healthBarContainer.addChild(healthBarFill);
	healthBarContainer.y = -50;
	self.addChild(healthBarContainer);
	// Movement variables
	var targetX = CENTER_X;
	var targetY = CENTER_Y;
	self.update = function () {
		// Move towards tower
		var dx = targetX - self.x;
		var dy = targetY - self.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		if (dist < 50) {
			// Attack tower
			if (tower.takeDamage(self.damage)) {
				return "gameover"; // Tower destroyed
			}
			// Move away slightly to prevent continuous damage
			self.x -= dx * 0.5;
			self.y -= dy * 0.5;
		} else {
			// Move towards tower
			self.x += dx / dist * self.speed;
			self.y += dy / dist * self.speed;
		}
		// Update health bar
		healthBarFill.scale.x = self.health / self.maxHealth;
		return null;
	};
	self.takeDamage = function (amount) {
		self.health -= amount;
		return self.health <= 0; // Return true if zombie is killed
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x000000
});

/**** 
* Game Code
****/ 
/**** 
* Game Variables
****/ 
var GAME_WIDTH = 2048;
var GAME_HEIGHT = 2732;
var CENTER_X = GAME_WIDTH / 2;
var CENTER_Y = GAME_HEIGHT / 2;
// Game state
var isGameActive = false;
var waitingForNextWave = false;
var waveCompleteText;
var bonusText;
var waveTextInterval;
// Game objects
var tower;
var upgradePanel;
var statusBar;
var cooldownIndicator;
var background;
// Game arrays
var zombies = [];
var bullets = [];
var explosions = [];
var targets = [];
// Game stats
var wave = 1;
var zombiesInWave = 0;
var waveInterval = 60; // Frames between zombie spawns
var zombiesKilled = 0;
var gold = 200; // Starting gold
var manualCooldown = 0;
/**** 
* Game Functions
****/ 
function startGame() {
	// Reset game variables
	isGameActive = true;
	waitingForNextWave = false;
	wave = 1;
	zombiesKilled = 0;
	gold = 200;
	zombies = [];
	bullets = [];
	explosions = [];
	targets = [];
	LK.playMusic('background');
	// Create game objects
	background = LK.getAsset('background', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	game.addChild(background);
	// Create tower in center
	tower = new Tower();
	tower.x = CENTER_X;
	tower.y = CENTER_Y;
	game.addChild(tower);
	// Create upgrade panel at bottom
	upgradePanel = new UpgradePanel();
	upgradePanel.x = CENTER_X;
	upgradePanel.y = GAME_HEIGHT;
	upgradePanel.updateGold(gold);
	game.addChild(upgradePanel);
	// Create status bar at top
	statusBar = new StatusBar();
	statusBar.x = CENTER_X;
	statusBar.y = 0;
	game.addChild(statusBar);
	// Create cooldown indicator for manual shooting
	cooldownIndicator = new CooldownIndicator();
	cooldownIndicator.x = CENTER_X;
	cooldownIndicator.y = GAME_HEIGHT - 480; // Position above upgrade panel
	game.addChild(cooldownIndicator);
	// Start first wave
	startWave();
}
function startWave() {
	// Clean up any previous wave text elements
	if (waveCompleteText) {
		waveCompleteText.destroy();
		waveCompleteText = null;
	}
	if (bonusText) {
		bonusText.destroy();
		bonusText = null;
	}
	if (waveTextInterval) {
		LK.clearInterval(waveTextInterval);
		waveTextInterval = null;
	}
	// Reset wave flag
	waitingForNextWave = false;
	// Update status bar
	statusBar.updateWave(wave);
	// Calculate zombies for this wave
	zombiesInWave = 10 + wave * 5;
	waveInterval = Math.max(20, 60 - wave * 2); // Spawn faster in later waves
	// Show wave start message
	var waveText = new Text2("WAVE " + wave + " INCOMING!", {
		size: 80,
		fill: 0xff3333
	});
	waveText.x = CENTER_X;
	waveText.y = CENTER_Y;
	waveText.anchor.set(0.5);
	game.addChild(waveText);
	var zombiesText = new Text2(zombiesInWave + " ZOMBIES", {
		size: 60,
		fill: 0xff3333
	});
	zombiesText.x = CENTER_X;
	zombiesText.y = CENTER_Y + 100;
	zombiesText.anchor.set(0.5);
	game.addChild(zombiesText);
	LK.getSound('waveStart').play();
	// Fade out wave text
	var fadeInterval = LK.setInterval(function () {
		waveText.alpha -= 0.02;
		zombiesText.alpha -= 0.02;
		if (waveText.alpha <= 0) {
			waveText.destroy();
			zombiesText.destroy();
			LK.clearInterval(fadeInterval);
		}
	}, 30);
}
function spawnZombie() {
	if (zombiesInWave <= 0) {
		return;
	}
	// Spawn a zombie at random edge position
	var zombie = new Zombie(wave);
	// Calculate spawn position (edge of screen)
	var side = Math.floor(Math.random() * 4); // 0: top, 1: right, 2: bottom, 3: left
	switch (side) {
		case 0:
			// Top
			zombie.x = Math.random() * GAME_WIDTH;
			zombie.y = 0;
			break;
		case 1:
			// Right
			zombie.x = GAME_WIDTH;
			zombie.y = Math.random() * GAME_HEIGHT;
			break;
		case 2:
			// Bottom
			zombie.x = Math.random() * GAME_WIDTH;
			zombie.y = GAME_HEIGHT;
			break;
		case 3:
			// Left
			zombie.x = 0;
			zombie.y = Math.random() * GAME_HEIGHT;
			break;
	}
	game.addChild(zombie);
	zombies.push(zombie);
	zombiesInWave--;
}
function gameOver() {
	isGameActive = false;
	LK.getSound('gameOver').play();
	// Show game over text
	var gameOverText = new Text2("GAME OVER", {
		size: 100,
		fill: 0xff0000
	});
	gameOverText.x = CENTER_X;
	gameOverText.y = CENTER_Y;
	gameOverText.anchor.set(0.5);
	game.addChild(gameOverText);
	var waveText = new Text2("Survived to Wave " + wave, {
		size: 60,
		fill: 0xffffff
	});
	waveText.x = CENTER_X;
	waveText.y = CENTER_Y + 80;
	waveText.anchor.set(0.5);
	game.addChild(waveText);
	var scoreText = new Text2("Zombies Killed: " + zombiesKilled, {
		size: 50,
		fill: 0xffffff
	});
	scoreText.x = CENTER_X;
	scoreText.y = CENTER_Y + 150;
	scoreText.anchor.set(0.5);
	game.addChild(scoreText);
	// Set final score (waves survived * zombies killed)
	LK.setScore(wave * zombiesKilled);
	// Show game over screen after delay
	LK.setTimeout(function () {
		LK.showGameOver();
	}, 3000);
}
/**** 
* Event Handlers
****/ 
game.on('down', function (x, y, obj) {
	if (!isGameActive) {
		return;
	}
	var event = obj;
	var pos = game.toLocal(event.global);
	// Check if clicking in upgrade panel area
	if (pos.y > GAME_HEIGHT - 400) {
		var upgradeCost = upgradePanel.checkUpgradeClick(pos.x, pos.y, gold);
		if (upgradeCost > 0) {
			gold -= upgradeCost;
			upgradePanel.updateGold(gold);
		}
	} else {
		// Manual targeting - can only fire once per second
		if (manualCooldown <= 0) {
			// Create target indicator
			var target = new ManualTarget();
			target.x = pos.x;
			target.y = pos.y;
			game.addChild(target);
			targets.push(target);
			// Fire at clicked location
			tower.manualShoot(pos.x, pos.y);
			manualCooldown = 60; // 1 second cooldown
		}
	}
});
/**** 
* Game Loop
****/ 
LK.on('tick', function () {
	if (!isGameActive) {
		return;
	}
	// Update tower
	tower.update();
	// Update upgrade panel
	upgradePanel.update();
	// Update cooldown indicator
	cooldownIndicator.update(manualCooldown, 60);
	// Update status bar stats
	statusBar.updateStats(zombiesKilled, wave * zombiesKilled);
	// Update bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		if (bullets[i].update()) {
			bullets[i].destroy();
			bullets.splice(i, 1);
			continue;
		}
		// Check for zombie hits
		for (var j = zombies.length - 1; j >= 0; j--) {
			if (bullets[i] && bullets[i].intersects(zombies[j])) {
				if (zombies[j].takeDamage(bullets[i].damage)) {
					// Zombie killed
					var explosion = new Explosion();
					explosion.x = zombies[j].x;
					explosion.y = zombies[j].y;
					game.addChild(explosion);
					explosions.push(explosion);
					// Add gold
					gold += zombies[j].value;
					upgradePanel.updateGold(gold);
					// Show gold pop-up
					var goldPop = new Text2("+" + zombies[j].value, {
						size: 30,
						fill: 0xffcc00
					});
					goldPop.x = zombies[j].x;
					goldPop.y = zombies[j].y - 50;
					goldPop.anchor.set(0.5);
					game.addChild(goldPop);
					// Fade out gold text
					var fadeInterval = LK.setInterval(function () {
						goldPop.alpha -= 0.05;
						goldPop.y -= 1;
						if (goldPop.alpha <= 0) {
							goldPop.destroy();
							LK.clearInterval(fadeInterval);
						}
					}, 30);
					LK.getSound('zombieDeath').play();
					zombies[j].destroy();
					zombies.splice(j, 1);
					zombiesKilled++;
				}
				// Remove bullet
				bullets[i].destroy();
				bullets.splice(i, 1);
				break;
			}
		}
	}
	// Update zombies
	for (var k = zombies.length - 1; k >= 0; k--) {
		var result = zombies[k].update();
		if (result === "gameover") {
			gameOver();
			return;
		}
	}
	// Update explosions
	for (var l = explosions.length - 1; l >= 0; l--) {
		if (explosions[l].update()) {
			explosions[l].destroy();
			explosions.splice(l, 1);
		}
	}
	// Update targets
	for (var m = targets.length - 1; m >= 0; m--) {
		if (targets[m].update()) {
			targets[m].destroy();
			targets.splice(m, 1);
		}
	}
	// Spawn zombies
	if (LK.ticks % waveInterval === 0 && zombiesInWave > 0) {
		spawnZombie();
	}
	// Check if wave is complete
	if (zombiesInWave <= 0 && zombies.length === 0 && !waitingForNextWave) {
		// Set flag to prevent multiple wave completions
		waitingForNextWave = true;
		// Start next wave after delay
		wave++;
		LK.setTimeout(function () {
			startWave();
		}, 3000);
		// Grant bonus gold between waves
		var bonus = 50 + (wave - 1) * 10;
		gold += bonus;
		upgradePanel.updateGold(gold);
		// Show wave complete message
		waveCompleteText = new Text2("WAVE " + (wave - 1) + " COMPLETE!", {
			size: 80,
			fill: 0x33ff33
		});
		waveCompleteText.x = CENTER_X;
		waveCompleteText.y = CENTER_Y;
		waveCompleteText.anchor.set(0.5);
		game.addChild(waveCompleteText);
		bonusText = new Text2("BONUS: +" + bonus + " GOLD", {
			size: 60,
			fill: 0xffcc00
		});
		bonusText.x = CENTER_X;
		bonusText.y = CENTER_Y + 100;
		bonusText.anchor.set(0.5);
		game.addChild(bonusText);
		// Fade out text
		waveTextInterval = LK.setInterval(function () {
			waveCompleteText.alpha -= 0.02;
			bonusText.alpha -= 0.02;
			if (waveCompleteText.alpha <= 0) {
				waveCompleteText.destroy();
				bonusText.destroy();
				LK.clearInterval(waveTextInterval);
				waveCompleteText = null;
				bonusText = null;
				waveTextInterval = null;
			}
		}, 30);
	}
	// Update manual cooldown
	if (manualCooldown > 0) {
		manualCooldown--;
	}
});
// Start the game
startGame();

===================================================================
--- original.js
+++ change.js
@@ -299,8 +299,42 @@
 		anchorX: 0.5,
 		anchorY: 1
 	});
 	// Create upgrade buttons
+	self.createUpgradeButton = function (label, position) {
+		var button = new Container();
+		var buttonGraphics = button.attachAsset('upgradeButton', {
+			anchorX: 0.5,
+			anchorY: 0.5
+		});
+		var buttonText = new Text2(label, {
+			size: 30,
+			fill: 0xffffff
+		});
+		buttonText.anchor.set(0.5);
+		buttonText.y = -20;
+		button.addChild(buttonText);
+		var costText = new Text2("", {
+			size: 24,
+			fill: 0xffcc00
+		});
+		costText.anchor.set(0.5);
+		costText.y = 20;
+		button.addChild(costText);
+		button.x = -670 + position * 450;
+		button.y = -200;
+		self.addChild(button);
+		return {
+			container: button,
+			costText: costText,
+			bounds: {
+				x: button.x - 225,
+				y: button.y - 50,
+				width: 450,
+				height: 100
+			}
+		};
+	};
 	var buttons = {
 		damage: self.createUpgradeButton("Damage", 0),
 		fireRate: self.createUpgradeButton("Fire Rate", 1),
 		range: self.createUpgradeButton("Range", 2),