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

/**** 
* Classes
****/ 
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	var bulletGraphics = self.attachAsset('attackEffect', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	bulletGraphics.scaleX = 0.5;
	bulletGraphics.scaleY = 0.5;
	// Set bullet speed based on boost status
	self.speed = bulletSpeedBoostTimer > 0 ? baseBulletSpeed * 1.5 : baseBulletSpeed;
	self.targetX = 0;
	self.targetY = 0;
	self.damage = 0;
	self.isPlayerBullet = true;
	self.targetEnemy = null; // Specific enemy this bullet is targeting
	self.update = function () {
		// Check for direct collision with enemies/player regardless of distance
		if (self.isPlayerBullet) {
			// Only check collision with the specific target enemy
			if (self.targetEnemy && !self.targetEnemy.isRespawning && !self.targetEnemy.destroyed && self.intersects(self.targetEnemy)) {
				self.targetEnemy.takeDamage(self.damage);
				self.destroy();
				return;
			}
		} else {
			// Enemy bullet hitting player
			if (!player.isRespawning && self.intersects(player)) {
				player.takeDamage(self.damage);
				self.destroy();
				return;
			}
		}
		var dx = self.targetX - self.x;
		var dy = self.targetY - self.y;
		var distance = Math.sqrt(dx * dx + dy * dy);
		// If reached target position, destroy bullet
		if (distance < self.speed) {
			self.destroy();
			return;
		}
		// Move towards target
		var moveX = dx / distance * self.speed;
		var moveY = dy / distance * self.speed;
		self.x += moveX;
		self.y += moveY;
		// Remove if out of bounds
		if (self.x < 0 || self.x > 2048 || self.y < 0 || self.y > 2732) {
			self.destroy();
		}
	};
	return self;
});
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	var enemyGraphics = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var healthBarBg = self.attachAsset('healthBarBg', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 0,
		y: -60
	});
	var healthBar = self.attachAsset('healthBar', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 0,
		y: -60
	});
	self.maxHealth = 30; // Reduced health for faster kills like Vampire Survivors
	self.health = 30;
	self.speed = 2;
	self.attackRange = 120;
	self.attackDamage = 8; // Higher damage but less health overall
	self.attackCooldown = 0;
	self.isRespawning = false;
	self.respawnTimer = 0;
	self.aiTimer = 0;
	self.spawnImmunityTimer = 0; // Prevents attacking immediately after spawn
	self.targetX = 0;
	self.targetY = 0;
	self.takeDamage = function (damage) {
		if (self.isRespawning || self.health <= 0) return; // Don't take damage if already dead
		// Vampire Survivors style damage - each hit does significant damage but not instant kill
		self.health -= damage;
		if (self.health < 0) self.health = 0;
		self.updateHealthBar();
		// Flash red when taking damage
		tween(enemyGraphics, {
			tint: 0xFF0000
		}, {
			duration: 200,
			onFinish: function onFinish() {
				tween(enemyGraphics, {
					tint: 0xFFFFFF
				}, {
					duration: 200
				});
			}
		});
		if (self.health <= 0) {
			self.die();
		}
		LK.getSound('hit').play();
	};
	self.updateHealthBar = function () {
		var healthPercent = self.health / self.maxHealth;
		healthBar.scaleX = healthPercent;
		if (healthPercent > 0.6) {
			healthBar.tint = 0x00FF00;
		} else if (healthPercent > 0.3) {
			healthBar.tint = 0xFFFF00;
		} else {
			healthBar.tint = 0xFF0000;
		}
	};
	self.die = function () {
		self.isRespawning = true;
		self.respawnTimer = 180; // 3 seconds at 60fps
		enemyGraphics.visible = false;
		healthBar.visible = false;
		healthBarBg.visible = false;
		// Move enemy far off-screen during respawn to prevent collision issues
		self.x = -1000;
		self.y = -1000;
		// Increment killed count and spawn new enemy only if under limit
		enemiesKilled++;
		score++;
		scoreText.setText('Score: ' + score);
		if (enemies.length < maxEnemies) {
			spawnNewEnemy();
		}
	};
	self.respawn = function () {
		self.health = self.maxHealth;
		// Set position first before making visible
		self.x = 300 + Math.random() * 1400;
		self.y = 400 + Math.random() * 1800;
		// Reset spawn immunity
		self.spawnImmunityTimer = 60; // 1 second of spawn immunity
		// Then update state and make visible
		self.isRespawning = false;
		self.respawnTimer = 0;
		enemyGraphics.visible = true;
		enemyGraphics.alpha = 1;
		healthBar.visible = true;
		healthBarBg.visible = true;
		self.updateHealthBar();
		LK.getSound('respawn').play();
	};
	self.attack = function () {
		if (self.attackCooldown > 0 || self.isRespawning || self.spawnImmunityTimer > 0) return;
		self.attackCooldown = 120; // 2 second cooldown
		if (!player.isRespawning) {
			// Create bullet projectile towards player
			var bullet = game.addChild(new Bullet());
			bullet.x = self.x;
			bullet.y = self.y;
			bullet.targetX = player.x;
			bullet.targetY = player.y;
			bullet.damage = self.attackDamage;
			bullet.isPlayerBullet = false;
			bullets.push(bullet);
		}
		// Create attack effect
		var attackEffect = LK.getAsset('attackEffect', {
			anchorX: 0.5,
			anchorY: 0.5
		});
		attackEffect.x = self.x;
		attackEffect.y = self.y;
		attackEffect.alpha = 0.7;
		attackEffect.tint = 0xFF4444;
		attackEffect.scaleX = 0.8;
		attackEffect.scaleY = 0.8;
		game.addChild(attackEffect);
		// Scale and fade out attack effect
		tween(attackEffect, {
			scaleX: 1.2,
			scaleY: 1.2,
			alpha: 0
		}, {
			duration: 200,
			onFinish: function onFinish() {
				attackEffect.destroy();
			}
		});
		LK.getSound('attack').play();
	};
	self.update = function () {
		if (self.attackCooldown > 0) {
			self.attackCooldown--;
		}
		if (self.spawnImmunityTimer > 0) {
			self.spawnImmunityTimer--;
			// Flash during spawn immunity period
			if (self.spawnImmunityTimer % 10 < 5) {
				enemyGraphics.alpha = 0.7;
			} else {
				enemyGraphics.alpha = 1;
			}
		}
		if (self.isRespawning) {
			self.respawnTimer--;
			if (self.respawnTimer <= 0) {
				self.respawn();
			}
			return;
		}
		// Chase player AI - move towards player and attack when close
		if (!player.isRespawning) {
			var dx = player.x - self.x;
			var dy = player.y - self.y;
			var playerDistance = Math.sqrt(dx * dx + dy * dy);
			// Move towards player with speed multiplier
			var currentSpeed = self.speed * enemySpeedMultiplier;
			if (playerDistance > currentSpeed) {
				// Create a formation around the player instead of direct chase
				// Update AI timer for random movement changes
				self.aiTimer++;
				if (self.aiTimer >= 60) {
					// Change direction every second
					self.aiTimer = 0;
					// Calculate a preferred distance from player (spread enemies out)
					var preferredDistance = 180 + Math.random() * 120; // 180-300 pixels from player
					// If too close to preferred distance, move in a circular pattern
					if (playerDistance < preferredDistance + 50) {
						// Move in circular pattern around player
						var circleAngle = Math.atan2(dy, dx) + (Math.random() - 0.5) * Math.PI; // Add large random offset
						var moveX = Math.cos(circleAngle) * currentSpeed * 0.7; // Slower circular movement
						var moveY = Math.sin(circleAngle) * currentSpeed * 0.7;
					} else {
						// Generate random offset angle (-60 to +60 degrees) for wider spread
						var offsetAngle = (Math.random() - 0.5) * Math.PI / 1.5; // ±60 degrees in radians
						var baseAngle = Math.atan2(dy, dx);
						var newAngle = baseAngle + offsetAngle;
						var moveX = Math.cos(newAngle) * currentSpeed * 0.8; // Slightly slower approach
						var moveY = Math.sin(newAngle) * currentSpeed * 0.8;
					}
				} else {
					// Use stored movement direction with slight randomness
					var moveX = dx / playerDistance * currentSpeed * 0.9;
					var moveY = dy / playerDistance * currentSpeed * 0.9;
				}
				self.x += moveX;
				self.y += moveY;
			}
			// Attack if close enough to player
			if (playerDistance <= self.attackRange) {
				self.attack();
			}
		}
		// Check collision with other enemies and push away if overlapping
		for (var e = 0; e < enemies.length; e++) {
			var otherEnemy = enemies[e];
			if (otherEnemy !== self && !otherEnemy.isRespawning && !self.isRespawning) {
				var dx = otherEnemy.x - self.x;
				var dy = otherEnemy.y - self.y;
				var distance = Math.sqrt(dx * dx + dy * dy);
				var minDistance = 120; // Reduced minimum distance to allow enemies closer together
				if (distance < minDistance && distance > 0) {
					// Calculate push direction (away from other enemy) with reduced force
					var pushStrength = (minDistance - distance) * 1.2; // Reduced push force
					var pushX = -(dx / distance) * pushStrength;
					var pushY = -(dy / distance) * pushStrength;
					// Apply moderate push force to separate enemies
					self.x += pushX;
					self.y += pushY;
					// Also apply counter-force to the other enemy for better separation
					otherEnemy.x += dx / distance * pushStrength * 0.5;
					otherEnemy.y += dy / distance * pushStrength * 0.5;
				}
			}
		}
		// Keep enemy in bounds
		if (self.x < 150) self.x = 150;
		if (self.x > 1898) self.x = 1898;
		if (self.y < 150) self.y = 150;
		if (self.y > 2582) self.y = 2582;
	};
	return self;
});
var HealthPack = Container.expand(function () {
	var self = Container.call(this);
	var healthPackGraphics = self.attachAsset('healthPack', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.healAmount = 25; // Heal amount (50% of max health for new system)
	self.lifetime = 600; // 10 seconds at 60fps
	// Pulse animation for visibility
	var pulseDirection = 1;
	var pulseSpeed = 0.02;
	self.update = function () {
		// Pulse animation
		healthPackGraphics.scaleX += pulseDirection * pulseSpeed;
		healthPackGraphics.scaleY += pulseDirection * pulseSpeed;
		if (healthPackGraphics.scaleX > 1.3 || healthPackGraphics.scaleX < 0.8) {
			pulseDirection *= -1;
		}
		// Reduce lifetime
		self.lifetime--;
		if (self.lifetime <= 0) {
			self.destroy();
		}
		// Check collision with player
		if (!player.isRespawning && self.intersects(player)) {
			// Heal player
			var oldHealth = player.health;
			player.health = Math.min(player.maxHealth, player.health + self.healAmount);
			player.updateHealthBar();
			// Give immunity for 2 seconds
			player.immunityTimer = 120;
			// Increase bullet speed for 3 seconds
			bulletSpeedBoostTimer = 180; // 3 seconds at 60fps
			// Visual effect
			tween(healthPackGraphics, {
				scaleX: 2,
				scaleY: 2,
				alpha: 0
			}, {
				duration: 300,
				onFinish: function onFinish() {
					self.destroy();
				}
			});
			LK.getSound('heal').play();
		}
	};
	return self;
});
var Player = Container.expand(function () {
	var self = Container.call(this);
	var playerGraphics = self.attachAsset('player', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var healthBarBg = self.attachAsset('healthBarBg', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 0,
		y: -60
	});
	var healthBar = self.attachAsset('healthBar', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 0,
		y: -60
	});
	self.maxHealth = 50; // Reduced health like Vampire Survivors
	self.health = 50;
	self.speed = 8;
	self.attackRange = 100;
	self.attackDamage = 15; // Balanced damage for new health system
	self.attackCooldown = 0;
	self.isRespawning = false;
	self.respawnTimer = 0;
	self.immunityTimer = 0; // Immunity period after respawn
	self.takeDamage = function (damage, source) {
		if (self.isRespawning || self.immunityTimer > 0) return;
		// Prevent damage from explosions and enemy spawning
		if (source === 'explosion' || source === 'spawn') {
			return;
		}
		self.health -= damage;
		if (self.health < 0) self.health = 0;
		self.updateHealthBar();
		// Flash red when taking damage
		tween(playerGraphics, {
			tint: 0xFF0000
		}, {
			duration: 200,
			onFinish: function onFinish() {
				tween(playerGraphics, {
					tint: 0xFFFFFF
				}, {
					duration: 200
				});
			}
		});
		if (self.health <= 0) {
			self.die();
		}
		LK.getSound('hit').play();
	};
	self.updateHealthBar = function () {
		var healthPercent = self.health / self.maxHealth;
		healthBar.scaleX = healthPercent;
		if (healthPercent > 0.6) {
			healthBar.tint = 0x00FF00;
		} else if (healthPercent > 0.3) {
			healthBar.tint = 0xFFFF00;
		} else {
			healthBar.tint = 0xFF0000;
		}
	};
	self.die = function () {
		// Show game over screen which will reset the game
		LK.showGameOver();
	};
	self.respawn = function () {
		self.health = self.maxHealth;
		self.isRespawning = false;
		self.respawnTimer = 0;
		playerGraphics.alpha = 1;
		healthBar.visible = true;
		healthBarBg.visible = true;
		self.updateHealthBar();
		// Respawn at center position since map is reset
		self.x = 500;
		self.y = 1000;
		// Add brief immunity period after respawn
		self.immunityTimer = 180; // 3 seconds of immunity
		// Spawn initial enemies after map reset
		for (var i = 0; i < 3; i++) {
			spawnNewEnemy();
		}
		LK.getSound('respawn').play();
	};
	// Vampire Survivors style automatic shooting - no manual attack method needed
	self.update = function () {
		if (self.attackCooldown > 0) {
			self.attackCooldown--;
		}
		if (self.immunityTimer > 0) {
			self.immunityTimer--;
			// Flash during immunity period
			if (self.immunityTimer % 10 < 5) {
				playerGraphics.alpha = 0.5;
			} else {
				playerGraphics.alpha = 1;
			}
		}
		if (self.isRespawning) {
			self.respawnTimer--;
			if (self.respawnTimer <= 0) {
				self.respawn();
			}
			return;
		}
		// Vampire Survivors style automatic continuous shooting
		if (self.attackCooldown <= 0) {
			// Find closest enemy within range
			var closestEnemy = null;
			var closestDistance = Infinity;
			var maxRange = 400; // Maximum shooting range
			for (var i = 0; i < enemies.length; i++) {
				var enemy = enemies[i];
				if (!enemy.isRespawning) {
					var distance = Math.sqrt(Math.pow(enemy.x - self.x, 2) + Math.pow(enemy.y - self.y, 2));
					if (distance < closestDistance && distance <= maxRange) {
						closestDistance = distance;
						closestEnemy = enemy;
					}
				}
			}
			if (closestEnemy) {
				// Set attack cooldown based on fire rate
				var baseFireRate = 30; // Base frames between shots (faster than before)
				var fireRateReduction = Math.min(fireRateBoostLevel * 2, baseFireRate * 0.4);
				self.attackCooldown = baseFireRate - fireRateReduction;
				// Create bullet projectile
				var bullet = game.addChild(new Bullet());
				bullet.x = self.x;
				bullet.y = self.y;
				bullet.targetX = closestEnemy.x;
				bullet.targetY = closestEnemy.y;
				bullet.damage = self.attackDamage;
				bullet.isPlayerBullet = true;
				bullet.targetEnemy = closestEnemy;
				bullets.push(bullet);
				// Create muzzle flash effect
				var attackEffect = LK.getAsset('attackEffect', {
					anchorX: 0.5,
					anchorY: 0.5
				});
				attackEffect.x = self.x;
				attackEffect.y = self.y;
				attackEffect.alpha = 0.7;
				attackEffect.tint = 0x4499FF;
				attackEffect.scaleX = 0.6;
				attackEffect.scaleY = 0.6;
				game.addChild(attackEffect);
				// Scale and fade out attack effect
				tween(attackEffect, {
					scaleX: 1.0,
					scaleY: 1.0,
					alpha: 0
				}, {
					duration: 150,
					onFinish: function onFinish() {
						attackEffect.destroy();
					}
				});
				LK.getSound('attack').play();
			}
		}
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// Create arena background
var arena = game.addChild(LK.getAsset('arena', {
	anchorX: 0.5,
	anchorY: 0.5
}));
arena.x = 2048 / 2;
arena.y = 2732 / 2;
// Game variables
var player;
var enemies = [];
var bullets = [];
var moveUp = false;
var moveDown = false;
var moveLeft = false;
var moveRight = false;
var targetX = 0;
var targetY = 0;
var isMovingToTarget = false;
var enemiesKilled = 0;
var score = 0;
var baseFireRate = 30; // Base attack cooldown - Vampire Survivors style faster firing
var currentFireRate = 30;
var fireRateBoostLevel = 0; // Tracks fire rate improvements
var maxEnemies = 8; // Base maximum number of enemies allowed
var enemySpeedMultiplier = 1.0; // Gradually increases enemy speed
var explosionRadius = 150; // Radius for chain explosions
var difficultyLevel = 0; // Current difficulty level
var lastDifficultyScore = 0; // Score at last difficulty increase
var healthPacks = [];
var lastHealthPackSpawn = 0;
var bulletSpeedBoostTimer = 0; // Timer for bullet speed boost
var baseBulletSpeed = 15; // Base bullet speed
var enemySpawnTimer = 0; // Timer for continuous enemy spawning
var baseSpawnInterval = 120; // Base spawn interval (2 seconds at 60fps)
var nextHealthRestoreScore = 1000; // Score threshold for next health restore
var hasRestoredHealthAtThreshold = false; // Track if health was restored at current threshold
// Start main music
LK.playMusic('Main');
// Initialize music state tracking
game.main1Playing = false;
game.main3Playing = false;
game.randomMusicPlaying = false;
// Create player
player = game.addChild(new Player());
player.x = 500;
player.y = 1000;
// Function to spawn new enemy from off-screen edges (Vampire Survivors style)
function spawnNewEnemy() {
	var enemy = game.addChild(new Enemy());
	// Choose random edge to spawn from (off-screen)
	var spawnSide = Math.floor(Math.random() * 4); // 0=top, 1=right, 2=bottom, 3=left
	var spawnOffset = Math.random(); // Random position along edge (0% to 100%)
	// Spawn outside visible area for true Vampire Survivors effect
	var offScreenDistance = 100; // Distance outside visible area
	switch (spawnSide) {
		case 0:
			// Top edge - spawn above screen
			enemy.x = spawnOffset * 2048;
			enemy.y = -offScreenDistance;
			break;
		case 1:
			// Right edge - spawn to the right of screen
			enemy.x = 2048 + offScreenDistance;
			enemy.y = spawnOffset * 2732;
			break;
		case 2:
			// Bottom edge - spawn below screen
			enemy.x = spawnOffset * 2048;
			enemy.y = 2732 + offScreenDistance;
			break;
		case 3:
			// Left edge - spawn to the left of screen
			enemy.x = -offScreenDistance;
			enemy.y = spawnOffset * 2732;
			break;
	}
	// Give new enemies a brief spawn immunity to prevent instant collision damage
	enemy.spawnImmunityTimer = 60; // 1 second of spawn immunity
	enemy.targetX = enemy.x;
	enemy.targetY = enemy.y;
	enemies.push(enemy);
}
// Initial enemies will be spawned by the continuous spawning system
// No need for initial spawn - let the timer handle it
// UI Elements
var instructionText = new Text2('Tap to move - Auto attack enemies nearby', {
	size: 40,
	fill: 0xFFFFFF
});
instructionText.anchor.set(0.5, 0);
LK.gui.top.addChild(instructionText);
instructionText.y = 100;
// Score display
var scoreText = new Text2('Score: 0', {
	size: 50,
	fill: 0xFFD700
});
scoreText.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreText);
scoreText.y = 150;
var dragNode = null;
var lastTouchTime = 0;
// Touch controls
game.down = function (x, y, obj) {
	if (player.isRespawning) return;
	// Keep target position in bounds
	targetX = Math.max(150, Math.min(1898, x));
	targetY = Math.max(150, Math.min(2582, y));
	// Stop any current movement tween
	tween.stop(player, {
		x: true,
		y: true
	});
	// Calculate distance for duration (closer = faster)
	var distance = Math.sqrt(Math.pow(targetX - player.x, 2) + Math.pow(targetY - player.y, 2));
	var duration = Math.max(200, Math.min(1000, distance * 2)); // 200ms to 1000ms based on distance
	isMovingToTarget = true;
	// Tween player to target position
	tween(player, {
		x: targetX,
		y: targetY
	}, {
		duration: duration,
		easing: tween.easeOut,
		onFinish: function onFinish() {
			isMovingToTarget = false;
		}
	});
};
game.move = function (x, y, obj) {
	// No drag movement needed - player moves via tween to clicked position
};
game.up = function (x, y, obj) {
	// No action needed - player auto-attacks when moving
};
// Main game loop
game.update = function () {
	// Vampire Survivors style continuous enemy spawning
	enemySpawnTimer++;
	var currentSpawnInterval = Math.max(30, baseSpawnInterval - Math.floor(score / 50) * 10); // Faster spawning as score increases
	if (enemySpawnTimer >= currentSpawnInterval && enemies.length < maxEnemies + difficultyLevel) {
		spawnNewEnemy();
		enemySpawnTimer = 0; // Reset spawn timer
	}
	// Music transitions based on score
	if (score >= 100 && score < 500) {
		// Play main1 music from score 100 to 500
		if (!game.main1Playing) {
			LK.stopMusic();
			LK.playMusic('main1');
			game.main1Playing = true;
		}
	} else if (score >= 500 && score < 1500) {
		// Play main2 music from score 500 to 1500
		if (game.main1Playing) {
			LK.stopMusic();
			LK.playMusic('main2');
			game.main1Playing = false;
		}
	} else if (score >= 1500 && score < 3000) {
		// Play main3 music from score 1500 to 3000
		if (game.main1Playing || !game.main3Playing) {
			LK.stopMusic();
			LK.playMusic('main3');
			game.main1Playing = false;
			game.main3Playing = true;
		}
	} else if (score >= 3000) {
		// Random music rotation every 2000 points after 3000
		var musicThreshold = 3000 + Math.floor((score - 3000) / 2000) * 2000;
		if (score >= musicThreshold && score < musicThreshold + 50 && !game.randomMusicPlaying) {
			// Choose random music
			var musicTracks = ['main1', 'Main', 'main2', 'main3'];
			var randomTrack = musicTracks[Math.floor(Math.random() * musicTracks.length)];
			LK.stopMusic();
			LK.playMusic(randomTrack);
			game.main1Playing = false;
			game.main3Playing = false;
			game.randomMusicPlaying = true;
		} else if (score >= musicThreshold + 50) {
			game.randomMusicPlaying = false;
		}
	}
	// Update bullet speed boost timer
	if (bulletSpeedBoostTimer > 0) {
		bulletSpeedBoostTimer--;
	}
	// Check for fire rate boost every 100 kills
	var newFireRateBoostLevel = Math.floor(enemiesKilled / 100);
	if (newFireRateBoostLevel > fireRateBoostLevel) {
		fireRateBoostLevel = newFireRateBoostLevel;
		// Visual feedback for fire rate increase
		LK.effects.flashScreen(0x0099FF, 300); // Blue flash to indicate fire rate boost
	}
	// Check for difficulty increase every 25 points
	if (score - lastDifficultyScore >= 25) {
		difficultyLevel++;
		lastDifficultyScore = score;
		// Systematic enemy speed progression based on score ranges
		if (score <= 100) {
			// Early game: minimal speed increase
			enemySpeedMultiplier = 1.0 + score * 0.005; // Max 1.5x at score 100
		} else if (score <= 200) {
			// Mid game: moderate increase
			enemySpeedMultiplier = 1.5 + (score - 100) * 0.003; // 1.5x to 1.8x
		} else if (score <= 400) {
			// Late game: controlled increase
			enemySpeedMultiplier = 1.8 + (score - 200) * 0.002; // 1.8x to 2.2x
		} else {
			// End game: capped maximum speed
			enemySpeedMultiplier = Math.min(2.5, 2.2 + (score - 400) * 0.001); // Max 2.5x speed
		}
		// Spawn additional enemies based on difficulty level
		var enemiesToSpawn = Math.min(2, difficultyLevel); // Spawn 1-2 enemies per difficulty increase
		for (var d = 0; d < enemiesToSpawn && enemies.length < maxEnemies + difficultyLevel; d++) {
			spawnNewEnemy();
		}
		// Visual feedback for difficulty increase
		LK.effects.flashScreen(0x00FF00, 500); // Green flash to indicate difficulty increase
	}
	// Health restore system - restore health at score milestones (1000, 2000, 3000, etc.)
	if (score >= nextHealthRestoreScore && !hasRestoredHealthAtThreshold) {
		// Restore player health to full
		player.health = player.maxHealth;
		player.updateHealthBar();
		// Set flag to prevent multiple restores at same threshold
		hasRestoredHealthAtThreshold = true;
		// Set next threshold
		nextHealthRestoreScore += 1000;
		// Visual feedback for health restore
		LK.effects.flashScreen(0x00FF99, 800); // Green-cyan flash for health restore
	}
	// Reset health restore flag when score increases past threshold
	if (score >= nextHealthRestoreScore - 1000 && score < nextHealthRestoreScore) {
		hasRestoredHealthAtThreshold = false;
	}
	// Spawn health pack when player health is low (below 25%)
	if (player.health < player.maxHealth * 0.25 && LK.ticks - lastHealthPackSpawn > 300 &&
	// 5 second cooldown
	healthPacks.length === 0) {
		// Only one health pack at a time
		var healthPack = game.addChild(new HealthPack());
		// Spawn at random location
		healthPack.x = 300 + Math.random() * 1400;
		healthPack.y = 400 + Math.random() * 1800;
		healthPacks.push(healthPack);
		lastHealthPackSpawn = LK.ticks;
	}
	// Update all game objects
	player.update();
	for (var i = 0; i < enemies.length; i++) {
		enemies[i].update();
	}
	// Update health packs and clean up destroyed ones
	for (var i = healthPacks.length - 1; i >= 0; i--) {
		var healthPack = healthPacks[i];
		if (healthPack.destroyed) {
			healthPacks.splice(i, 1);
		} else {
			healthPack.update();
		}
	}
	// Update bullets and clean up destroyed ones
	for (var i = bullets.length - 1; i >= 0; i--) {
		var bullet = bullets[i];
		if (bullet.destroyed === true || !bullet.parent) {
			bullets.splice(i, 1);
		} else {
			bullet.update();
		}
	}
};