/**** 
* Classes
****/ 
// Bullet class
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletSprite = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5,
		flipY: 1 // flip vertically
	});
	// Target coordinates for the bullet
	self.targetX = null;
	self.targetY = null;
	self.speed = 48; // pixels per frame, positive value
	self.dirX = 0;
	self.dirY = -1;
	self.setTarget = function (tx, ty) {
		// Calculate direction vector
		var dx = tx - self.x;
		var dy = ty - self.y;
		var len = Math.sqrt(dx * dx + dy * dy);
		if (len > 0) {
			self.dirX = dx / len;
			self.dirY = dy / len;
		} else {
			self.dirX = 0;
			self.dirY = -1;
		}
		self.targetX = tx;
		self.targetY = ty;
	};
	self.update = function () {
		// Store lastX/lastY for event triggers
		if (typeof self.lastX === "undefined") self.lastX = self.x;
		if (typeof self.lastY === "undefined") self.lastY = self.y;
		// Move in direction
		self.x += self.dirX * self.speed;
		self.y += self.dirY * self.speed;
		// Rotate bullet sprite to face movement direction
		if (self.dirX !== 0 || self.dirY !== 0) {
			// atan2 returns angle in radians, 0 is to the right, so subtract Math.PI/2 to make 0 point up
			bulletSprite.rotation = Math.atan2(self.dirY, self.dirX) - Math.PI / 2;
		}
		// Update lastX/lastY for next frame
		self.lastX = self.x;
		self.lastY = self.y;
	};
	return self;
});
// Enemy class
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemySprite = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = enemySprite.width * 0.5;
	self.speed = 3 + Math.random() * 3; // much slower zombies
	self.dir = Math.random() < 0.5 ? -1 : 1;
	self.xSpeed = self.dir * (2 + Math.random() * 3); // also slow horizontal
	self.update = function () {
		self.y += self.speed;
		self.x += self.xSpeed;
		// Bounce off walls
		if (self.x < self.radius) {
			self.x = self.radius;
			self.xSpeed *= -1;
		}
		if (self.x > 2048 - self.radius) {
			self.x = 2048 - self.radius;
			self.xSpeed *= -1;
		}
	};
	return self;
});
// Obstacle class
var Obstacle = Container.expand(function () {
	var self = Container.call(this);
	var obsSprite = self.attachAsset('obstacle', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = obsSprite.width;
	self.height = obsSprite.height;
	self.speed = 12 + Math.random() * 8;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player class
var Player = Container.expand(function () {
	var self = Container.call(this);
	var playerSprite = self.attachAsset('player', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = playerSprite.width * 0.5;
	self.lives = 3;
	self.invincible = false;
	self.invincibleTicks = 0;
	self.shootCooldown = 0;
	self.update = function () {
		if (self.invincible) {
			self.invincibleTicks--;
			if (self.invincibleTicks <= 0) {
				self.invincible = false;
				playerSprite.alpha = 1;
			} else {
				// Flicker effect
				playerSprite.alpha = LK.ticks % 10 < 5 ? 0.4 : 1;
			}
		}
		if (self.shootCooldown > 0) self.shootCooldown--;
	};
	// Called when player is hit
	self.hit = function () {
		if (self.invincible) return;
		self.lives--;
		self.invincible = true;
		self.invincibleTicks = 90; // 1.5 seconds
		playerSprite.alpha = 0.4;
		LK.effects.flashObject(self, 0xff0000, 500);
		LK.getSound('hit').play();
	};
	// Called when player picks up a powerup
	self.powerup = function () {
		self.invincible = true;
		self.invincibleTicks = 180; // 3 seconds
		playerSprite.alpha = 0.4;
		LK.getSound('powerup').play();
	};
	return self;
});
// Powerup class
var Powerup = Container.expand(function () {
	var self = Container.call(this);
	var puSprite = self.attachAsset('powerup', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.radius = puSprite.width * 0.5;
	self.speed = 10;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// Music
// Sound effects
// Powerup: green ellipse
// Bullet: yellow box
// Obstacle: orange box
// Enemy: red ellipse
// Player character: blue box
// Game state variables
var player;
var bullets = [];
var enemies = [];
// Removed obstacles array as obstacles are deleted from the game
var powerups = [];
var dragNode = null;
var lastTouch = {
	x: 0,
	y: 0
};
var scoreTxt, livesTxt;
var spawnTick = 0;
var difficulty = 1; // wave number, always between 1 and 10
var gameOver = false;
// Goal object at the bottom
var goalObj = null;
// Wave system variables
var wave = 1; // current wave number (1-10)
var waveEnemyCount = 0; // number of enemies to spawn this wave
var waveEnemiesSpawned = 0; // how many enemies have been spawned this wave
var waveEnemiesDefeated = 0; // how many enemies have been defeated this wave
var waveInProgress = false;
// UI
scoreTxt = new Text2('0', {
	size: 120,
	fill: "#fff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
livesTxt = new Text2('♥♥♥', {
	size: 90,
	fill: 0xFF5252
});
livesTxt.anchor.set(1, 0);
LK.gui.topRight.addChild(livesTxt);
// Start music
LK.playMusic('arcadebg');
// Create player
player = new Player();
player.x = 2048 / 2;
player.y = 2732 - 350;
game.addChild(player);
// Add plus buttons to the right and left of the player
var plusBtnLeft = LK.getAsset('powerup', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: player.x - 370,
	y: player.y,
	scaleX: 1.5,
	scaleY: 1.5
});
var plusBtnRight = LK.getAsset('powerup', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: player.x + 370,
	y: player.y,
	scaleX: 1.5,
	scaleY: 1.5
});
game.addChild(plusBtnLeft);
game.addChild(plusBtnRight);
// Optionally, store for later use if you want to add interaction
// Create goal object at the bottom center
goalObj = LK.getAsset('obstacle', {
	anchorX: 0.5,
	anchorY: 0.5,
	x: 2048 / 2,
	y: 2732 - 100,
	scaleX: 1.2,
	scaleY: 1.2
});
game.addChild(goalObj);
// Helper: update lives display
function updateLives() {
	var s = '';
	for (var i = 0; i < player.lives; i++) s += '♥';
	livesTxt.setText(s);
}
// Helper: spawn enemy
function spawnEnemy() {
	var e = new Enemy();
	e.x = 200 + Math.random() * (2048 - 400);
	e.y = -100;
	enemies.push(e);
	game.addChild(e);
}
// Removed spawnObstacle function as obstacles are deleted from the game
// Helper: spawn powerup
function spawnPowerup() {
	var p = new Powerup();
	p.x = 200 + Math.random() * (2048 - 400);
	p.y = -80;
	powerups.push(p);
	game.addChild(p);
}
// Touch controls: drag player
game.down = function (x, y, obj) {
	// Don't allow drag from top left 100x100
	if (x < 100 && y < 100) return;
	if (player && !gameOver) {
		dragNode = player;
		lastTouch.x = x;
		lastTouch.y = y;
	}
};
game.move = function (x, y, obj) {
	if (dragNode && !gameOver) {
		// Player movement disabled: do not update player.x or player.y
		lastTouch.x = x;
		lastTouch.y = y;
	}
};
game.up = function (x, y, obj) {
	dragNode = null;
};
// Tap to shoot (anywhere except top left 100x100)
game.on('down', function (x, y, obj) {
	if (x < 100 && y < 100) return;
	if (player && !gameOver && player.shootCooldown <= 0) {
		var b = new Bullet();
		b.x = player.x;
		b.y = player.y - player.radius - 20;
		b.setTarget(x, y); // Set bullet direction toward tap
		bullets.push(b);
		game.addChild(b);
		player.shootCooldown = 12; // 0.2s
		LK.getSound('shoot').play();
	}
});
// Main game loop
game.update = function () {
	if (gameOver) return;
	// Wave-based enemy spawning logic
	if (!waveInProgress) {
		// Start new wave
		waveInProgress = true;
		waveEnemiesSpawned = 0;
		waveEnemiesDefeated = 0;
		waveEnemyCount = 5 + (wave - 1) * 2; // wave 1: 5, wave 2: 7, ..., wave 10: 23
		if (waveEnemyCount < 1) waveEnemyCount = 1;
		if (waveEnemyCount > 23) waveEnemyCount = 23;
	}
	// Player update
	player.update();
	// Spawn logic for current wave
	if (waveInProgress && waveEnemiesSpawned < waveEnemyCount) {
		// Spawn enemies at a fixed interval
		if (spawnTick % 30 === 0) {
			spawnEnemy();
			waveEnemiesSpawned++;
		}
	}
	if (spawnTick % 300 === 0 && Math.random() < 0.5) {
		spawnPowerup();
	}
	// Bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		var b = bullets[i];
		b.update();
		if (b.y < -60) {
			b.destroy();
			bullets.splice(i, 1);
			continue;
		}
		// Bullet hits enemy
		for (var j = enemies.length - 1; j >= 0; j--) {
			var e = enemies[j];
			if (b.intersects(e)) {
				LK.setScore(LK.getScore() + 10);
				scoreTxt.setText(LK.getScore());
				LK.getSound('enemyDown').play();
				e.destroy();
				enemies.splice(j, 1);
				b.destroy();
				bullets.splice(i, 1);
				waveEnemiesDefeated++;
				// If all enemies for this wave are defeated, advance to next wave
				if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
					wave++;
					if (wave > 10) wave = 10;
					waveInProgress = false;
				}
				break;
			}
		}
	}
	// Enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		var e = enemies[i];
		e.update();
		// Enemy reaches goal object
		if (goalObj && e.intersects(goalObj)) {
			if (!player.invincible) {
				player.hit();
				updateLives();
				if (player.lives <= 0) {
					gameOver = true;
					LK.effects.flashScreen(0xff0000, 1000);
					LK.showGameOver();
					return;
				}
			}
			e.destroy();
			enemies.splice(i, 1);
			waveEnemiesDefeated++;
			// If all enemies for this wave are defeated, advance to next wave
			if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
				wave++;
				if (wave > 10) wave = 10;
				waveInProgress = false;
			}
			continue;
		}
		if (e.y > 2732 + 100) {
			e.destroy();
			enemies.splice(i, 1);
			continue;
		}
		// Enemy hits player
		if (e.intersects(player)) {
			if (!player.invincible) {
				player.hit();
				updateLives();
				if (player.lives <= 0) {
					gameOver = true;
					LK.effects.flashScreen(0xff0000, 1000);
					LK.showGameOver();
					return;
				}
			}
			e.destroy();
			enemies.splice(i, 1);
			waveEnemiesDefeated++;
			// If all enemies for this wave are defeated, advance to next wave
			if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
				wave++;
				if (wave > 10) wave = 10;
				waveInProgress = false;
			}
		}
	}
	// Obstacles removed from game
	// Powerups
	for (var i = powerups.length - 1; i >= 0; i--) {
		var p = powerups[i];
		p.update();
		if (p.y > 2732 + 80) {
			p.destroy();
			powerups.splice(i, 1);
			continue;
		}
		// Powerup hits player
		if (p.intersects(player)) {
			player.powerup();
			LK.setScore(LK.getScore() + 50);
			scoreTxt.setText(LK.getScore());
			p.destroy();
			powerups.splice(i, 1);
		}
	}
};
// Score display
scoreTxt.setText(LK.getScore());
updateLives();

===================================================================
--- original.js
+++ change.js
@@ -181,8 +181,14 @@
 var difficulty = 1; // wave number, always between 1 and 10
 var gameOver = false;
 // Goal object at the bottom
 var goalObj = null;
+// Wave system variables
+var wave = 1; // current wave number (1-10)
+var waveEnemyCount = 0; // number of enemies to spawn this wave
+var waveEnemiesSpawned = 0; // how many enemies have been spawned this wave
+var waveEnemiesDefeated = 0; // how many enemies have been defeated this wave
+var waveInProgress = false;
 // UI
 scoreTxt = new Text2('0', {
 	size: 120,
 	fill: "#fff"
@@ -291,22 +297,27 @@
 });
 // Main game loop
 game.update = function () {
 	if (gameOver) return;
-	// Increase difficulty over time, clamp between 1 and 10
-	if (LK.ticks % 600 === 0) {
-		difficulty++;
-		if (difficulty > 10) difficulty = 10;
-		if (difficulty < 1) difficulty = 1;
+	// Wave-based enemy spawning logic
+	if (!waveInProgress) {
+		// Start new wave
+		waveInProgress = true;
+		waveEnemiesSpawned = 0;
+		waveEnemiesDefeated = 0;
+		waveEnemyCount = 5 + (wave - 1) * 2; // wave 1: 5, wave 2: 7, ..., wave 10: 23
+		if (waveEnemyCount < 1) waveEnemyCount = 1;
+		if (waveEnemyCount > 23) waveEnemyCount = 23;
 	}
 	// Player update
 	player.update();
-	// Spawn logic
-	spawnTick++;
-	if (spawnTick % Math.max(30 - difficulty * 2, 8) === 0) {
-		// spawn more zombies, higher chance
-		if (Math.random() < 0.85) spawnEnemy();
-		if (Math.random() < 0.25) spawnEnemy(); // sometimes spawn two at once
+	// Spawn logic for current wave
+	if (waveInProgress && waveEnemiesSpawned < waveEnemyCount) {
+		// Spawn enemies at a fixed interval
+		if (spawnTick % 30 === 0) {
+			spawnEnemy();
+			waveEnemiesSpawned++;
+		}
 	}
 	if (spawnTick % 300 === 0 && Math.random() < 0.5) {
 		spawnPowerup();
 	}
@@ -329,8 +340,15 @@
 				e.destroy();
 				enemies.splice(j, 1);
 				b.destroy();
 				bullets.splice(i, 1);
+				waveEnemiesDefeated++;
+				// If all enemies for this wave are defeated, advance to next wave
+				if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
+					wave++;
+					if (wave > 10) wave = 10;
+					waveInProgress = false;
+				}
 				break;
 			}
 		}
 	}
@@ -351,8 +369,15 @@
 				}
 			}
 			e.destroy();
 			enemies.splice(i, 1);
+			waveEnemiesDefeated++;
+			// If all enemies for this wave are defeated, advance to next wave
+			if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
+				wave++;
+				if (wave > 10) wave = 10;
+				waveInProgress = false;
+			}
 			continue;
 		}
 		if (e.y > 2732 + 100) {
 			e.destroy();
@@ -372,8 +397,15 @@
 				}
 			}
 			e.destroy();
 			enemies.splice(i, 1);
+			waveEnemiesDefeated++;
+			// If all enemies for this wave are defeated, advance to next wave
+			if (waveEnemiesDefeated >= waveEnemyCount && waveInProgress) {
+				wave++;
+				if (wave > 10) wave = 10;
+				waveInProgress = false;
+			}
 		}
 	}
 	// Obstacles removed from game
 	// Powerups