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

/**** 
* Classes
****/ 
// BuildTile class (for tower placement)
var BuildTile = Container.expand(function () {
	var self = Container.call(this);
	// Attach tile asset (box, light gray)
	var tileAsset = self.attachAsset('buildTile', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.occupied = false;
	self.tower = null;
	// For highlighting
	self.highlight = function (on) {
		tileAsset.tint = on ? 0x2ecc40 : 0xbdc3c7;
	};
	return self;
});
// Bullet class
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	// Attach bullet asset (small yellow box)
	var bulletAsset = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.target = null;
	self.damage = 5;
	self.speed = 24;
	self.update = function () {
		if (!self.target || self.target.health <= 0 || self.target.reachedBase) {
			self.destroyed = true;
			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 < 32) {
			// Hit
			self.target.takeDamage(self.damage);
			self.destroyed = true;
			return;
		}
		var moveDist = Math.min(self.speed, dist);
		self.x += dx / dist * moveDist;
		self.y += dy / dist * moveDist;
	};
	return self;
});
// Enemy (Creep) class
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	// Attach enemy asset (ellipse, purple)
	var enemyAsset = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Enemy stats
	self.maxHealth = 10 + (currentWave - 1) * 5;
	self.health = self.maxHealth;
	self.speed = 2 + (currentWave - 1) * 0.2; // Slightly faster each wave
	self.reward = 5 + (currentWave - 1) * 2;
	// Path progress
	self.pathIndex = 0;
	self.pathProgress = 0;
	// For hit flash
	self.isFlashing = false;
	// Move along path
	self.update = function () {
		if (self.pathIndex >= path.length - 1) return;
		var from = path[self.pathIndex];
		var to = path[self.pathIndex + 1];
		var dx = to.x - from.x;
		var dy = to.y - from.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		if (dist === 0) {
			self.pathIndex++;
			self.pathProgress = 0;
			return;
		}
		var moveDist = self.speed;
		self.pathProgress += moveDist;
		if (self.pathProgress >= dist) {
			self.pathIndex++;
			self.pathProgress = 0;
			if (self.pathIndex >= path.length - 1) {
				// Reached end
				self.x = to.x;
				self.y = to.y;
				self.reachedBase = true;
				return;
			}
		}
		var t = self.pathProgress / dist;
		self.x = from.x + dx * t;
		self.y = from.y + dy * t;
	};
	// Take damage
	self.takeDamage = function (dmg) {
		self.health -= dmg;
		if (!self.isFlashing) {
			self.isFlashing = true;
			tween(enemyAsset, {
				tint: 0xffffff
			}, {
				duration: 80,
				onFinish: function onFinish() {
					tween(enemyAsset, {
						tint: 0x8e44ad
					}, {
						duration: 120,
						onFinish: function onFinish() {
							self.isFlashing = false;
						}
					});
				}
			});
		}
	};
	return self;
});
// Tower class
var Tower = Container.expand(function () {
	var self = Container.call(this);
	// Attach tower asset (box, blue)
	var towerAsset = self.attachAsset('tower', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Tower stats
	self.level = 1;
	self.range = 320;
	self.damage = 5;
	self.fireRate = 60; // frames per shot
	self.cooldown = 0;
	// For upgrade flash
	self.isFlashing = false;
	// Show range circle (for placement)
	self.rangeCircle = self.attachAsset('rangeCircle', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0.15
	});
	self.rangeCircle.width = self.range * 2;
	self.rangeCircle.height = self.range * 2;
	self.rangeCircle.visible = false;
	// Upgrade tower
	self.upgrade = function () {
		if (self.level >= 3) return false;
		self.level++;
		self.damage += 5;
		self.range += 40;
		self.fireRate = Math.max(30, self.fireRate - 10);
		self.rangeCircle.width = self.range * 2;
		self.rangeCircle.height = self.range * 2;
		// Flash for upgrade
		if (!self.isFlashing) {
			self.isFlashing = true;
			tween(towerAsset, {
				tint: 0xffff00
			}, {
				duration: 120,
				onFinish: function onFinish() {
					tween(towerAsset, {
						tint: 0x3498db
					}, {
						duration: 180,
						onFinish: function onFinish() {
							self.isFlashing = false;
						}
					});
				}
			});
		}
		return true;
	};
	// Tower attack logic
	self.update = function () {
		if (self.cooldown > 0) {
			self.cooldown--;
			return;
		}
		// Find nearest enemy in range
		var nearest = null;
		var minDist = 99999;
		for (var i = 0; i < enemies.length; i++) {
			var e = enemies[i];
			var dx = e.x - self.x;
			var dy = e.y - self.y;
			var dist = Math.sqrt(dx * dx + dy * dy);
			if (dist <= self.range && dist < minDist) {
				nearest = e;
				minDist = dist;
			}
		}
		if (nearest) {
			// Shoot
			var b = new Bullet();
			b.x = self.x;
			b.y = self.y;
			b.target = nearest;
			b.damage = self.damage;
			b.speed = 24;
			b.lastX = b.x;
			b.lastY = b.y;
			bullets.push(b);
			game.addChild(b);
			self.cooldown = self.fireRate;
		}
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// Path definition (array of {x, y}), from top left to bottom right
var path = [{
	x: 180,
	y: 300
}, {
	x: 180,
	y: 1200
}, {
	x: 800,
	y: 1200
}, {
	x: 800,
	y: 2000
}, {
	x: 1800,
	y: 2000
}, {
	x: 1800,
	y: 2600
}];
// --- Start Game Button Logic ---
var gameStarted = false;
var startBtn = new Text2('▶ Start Game', {
	size: 120,
	fill: 0x27AE60
});
startBtn.anchor.set(0.5, 0.5);
LK.gui.center.addChild(startBtn);
function setStartBtnVisible(visible) {
	startBtn.visible = visible;
}
setStartBtnVisible(true);
startBtn.down = function (x, y, obj) {
	if (!gameStarted) {
		gameStarted = true;
		setStartBtnVisible(false);
		setNextWaveBtnVisible(true);
	}
};
// Hide all gameplay UI until game starts
setNextWaveBtnVisible(false);
if (typeof kpTxt !== "undefined") kpTxt.visible = false;
if (typeof healthTxt !== "undefined") healthTxt.visible = false;
if (typeof waveTxt !== "undefined") waveTxt.visible = false;
if (typeof nextWaveBtn !== "undefined") nextWaveBtn.visible = false;
// Show gameplay UI when game starts
function showGameplayUI() {
	kpTxt.visible = true;
	healthTxt.visible = true;
	waveTxt.visible = true;
	nextWaveBtn.visible = false;
}
var _origStartWave = startWave;
startWave = function startWave() {
	if (!gameStarted) return;
	showGameplayUI();
	_origStartWave();
};
// Buildable tile positions (not on path)
var buildTilePositions = [{
	x: 500,
	y: 600
}, {
	x: 1100,
	y: 800
}, {
	x: 400,
	y: 1600
}, {
	x: 1200,
	y: 1500
}, {
	x: 1700,
	y: 1000
}, {
	x: 1500,
	y: 2200
}, {
	x: 900,
	y: 2100
}];
// Global game state
var enemies = [];
var towers = [];
var bullets = [];
var buildTiles = [];
var baseHealth = 10;
var knowledgePoints = 30;
var currentWave = 1;
var maxWaves = 10;
var waveInProgress = false;
var waveTimer = null;
var spawnIndex = 0;
var spawnDelay = 40; // frames between spawns
var enemiesToSpawn = 0;
var selectedTile = null;
// Asset initialization
// Draw path (for visual reference)
for (var i = 0; i < path.length - 1; i++) {
	var from = path[i];
	var to = path[i + 1];
	var dx = to.x - from.x;
	var dy = to.y - from.y;
	var dist = Math.sqrt(dx * dx + dy * dy);
	var steps = Math.floor(dist / 40);
	for (var s = 0; s <= steps; s++) {
		var t = s / steps;
		var px = from.x + dx * t;
		var py = from.y + dy * t;
		var node = LK.getAsset('pathDot', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: 32,
			height: 32,
			color: 0x7f8c8d,
			shape: 'ellipse'
		});
		node.x = px;
		node.y = py;
		game.addChild(node);
	}
}
// Place buildable tiles
for (var i = 0; i < buildTilePositions.length; i++) {
	var pos = buildTilePositions[i];
	var tile = new BuildTile();
	tile.x = pos.x;
	tile.y = pos.y;
	buildTiles.push(tile);
	game.addChild(tile);
}
// Base indicator (ellipse, red)
var baseNode = LK.getAsset('base', {
	anchorX: 0.5,
	anchorY: 0.5,
	width: 160,
	height: 160,
	color: 0xe74c3c,
	shape: 'ellipse'
});
baseNode.x = path[path.length - 1].x;
baseNode.y = path[path.length - 1].y;
game.addChild(baseNode);
// GUI: Knowledge Points
var kpTxt = new Text2('KP: ' + knowledgePoints, {
	size: 90,
	fill: 0x222222
});
kpTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(kpTxt);
// GUI: Base Health
var healthTxt = new Text2('Base: ' + baseHealth, {
	size: 90,
	fill: 0xE74C3C
});
healthTxt.anchor.set(0.5, 0);
LK.gui.topRight.addChild(healthTxt);
// GUI: Wave
var waveTxt = new Text2('Wave: ' + currentWave + '/' + maxWaves, {
	size: 90,
	fill: 0x2980B9
});
waveTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(waveTxt);
// GUI: Next Wave Button
var nextWaveBtn = new Text2('▶ Next Wave', {
	size: 90,
	fill: 0x27AE60
});
nextWaveBtn.anchor.set(0.5, 0);
LK.gui.bottom.addChild(nextWaveBtn);
// Show/hide next wave button
function setNextWaveBtnVisible(visible) {
	nextWaveBtn.visible = visible;
}
setNextWaveBtnVisible(true);
// Start next wave
function startWave() {
	if (waveInProgress || currentWave > maxWaves) return;
	waveInProgress = true;
	setNextWaveBtnVisible(false);
	enemiesToSpawn = 6 + currentWave * 2;
	spawnIndex = 0;
}
// Next wave button event
nextWaveBtn.down = function (x, y, obj) {
	if (!waveInProgress && currentWave <= maxWaves) {
		startWave();
	}
};
// Build/upgrade tower on tile
function tryBuildOrUpgrade(tile) {
	if (tile.occupied) {
		// Try upgrade
		if (tile.tower.level < 3) {
			var upgradeCost = 20 + tile.tower.level * 15;
			if (knowledgePoints >= upgradeCost) {
				knowledgePoints -= upgradeCost;
				tile.tower.upgrade();
				kpTxt.setText('KP: ' + knowledgePoints);
			}
		}
	} else {
		// Build new tower
		var buildCost = 20;
		if (knowledgePoints >= buildCost) {
			knowledgePoints -= buildCost;
			var tower = new Tower();
			tower.x = tile.x;
			tower.y = tile.y;
			towers.push(tower);
			game.addChild(tower);
			tile.occupied = true;
			tile.tower = tower;
			kpTxt.setText('KP: ' + knowledgePoints);
		}
	}
}
// Highlight build tiles on touch
game.down = function (x, y, obj) {
	// Convert to game coordinates
	for (var i = 0; i < buildTiles.length; i++) {
		var tile = buildTiles[i];
		var dx = x - tile.x;
		var dy = y - tile.y;
		if (dx * dx + dy * dy < 70 * 70) {
			// Select this tile
			if (selectedTile && selectedTile !== tile) {
				selectedTile.highlight(false);
				if (selectedTile.tower) selectedTile.tower.rangeCircle.visible = false;
			}
			selectedTile = tile;
			tile.highlight(true);
			if (tile.tower) {
				tile.tower.rangeCircle.visible = true;
			} else {
				// Show a temp range circle for new tower
				if (!tile.tempRange) {
					tile.tempRange = LK.getAsset('rangeCircle', {
						anchorX: 0.5,
						anchorY: 0.5,
						alpha: 0.12
					});
					tile.tempRange.width = 640;
					tile.tempRange.height = 640;
					tile.tempRange.x = tile.x;
					tile.tempRange.y = tile.y;
					game.addChild(tile.tempRange);
				}
				tile.tempRange.visible = true;
			}
			return;
		}
	}
	// If tap on selected tile, build/upgrade
	if (selectedTile) {
		var dx = x - selectedTile.x;
		var dy = y - selectedTile.y;
		if (dx * dx + dy * dy < 70 * 70) {
			tryBuildOrUpgrade(selectedTile);
		}
		// Hide highlight and range
		selectedTile.highlight(false);
		if (selectedTile.tower) selectedTile.tower.rangeCircle.visible = false;
		if (selectedTile.tempRange) selectedTile.tempRange.visible = false;
		selectedTile = null;
	}
};
// Remove highlight/range on up
game.up = function (x, y, obj) {
	if (selectedTile) {
		selectedTile.highlight(false);
		if (selectedTile.tower) selectedTile.tower.rangeCircle.visible = false;
		if (selectedTile.tempRange) selectedTile.tempRange.visible = false;
		selectedTile = null;
	}
};
// Main game update
game.update = function () {
	// Spawn enemies for wave
	if (waveInProgress && enemiesToSpawn > 0 && LK.ticks % spawnDelay === 0) {
		var enemy = new Enemy();
		enemy.x = path[0].x;
		enemy.y = path[0].y;
		enemy.pathIndex = 0;
		enemy.pathProgress = 0;
		enemies.push(enemy);
		game.addChild(enemy);
		enemiesToSpawn--;
	}
	// Update enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		var e = enemies[i];
		e.update();
		if (e.health <= 0) {
			// Enemy defeated
			knowledgePoints += e.reward;
			kpTxt.setText('KP: ' + knowledgePoints);
			e.destroy();
			enemies.splice(i, 1);
		} else if (e.reachedBase) {
			// Enemy reached base
			baseHealth--;
			healthTxt.setText('Base: ' + baseHealth);
			e.destroy();
			enemies.splice(i, 1);
			LK.effects.flashScreen(0xe74c3c, 400);
			if (baseHealth <= 0) {
				LK.showGameOver();
				return;
			}
		}
	}
	// Update towers
	for (var i = 0; i < towers.length; i++) {
		towers[i].update();
	}
	// Update bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		var b = bullets[i];
		b.update();
		if (b.destroyed) {
			b.destroy();
			bullets.splice(i, 1);
		}
	}
	// End wave if all enemies defeated and none left to spawn
	if (waveInProgress && enemies.length === 0 && enemiesToSpawn === 0) {
		waveInProgress = false;
		currentWave++;
		if (currentWave > maxWaves) {
			LK.showYouWin();
			return;
		}
		waveTxt.setText('Wave: ' + currentWave + '/' + maxWaves);
		setNextWaveBtnVisible(true);
	}
};

===================================================================
--- original.js
+++ change.js
@@ -267,12 +267,12 @@
 	}
 };
 // Hide all gameplay UI until game starts
 setNextWaveBtnVisible(false);
-kpTxt.visible = false;
-healthTxt.visible = false;
-waveTxt.visible = false;
-nextWaveBtn.visible = false;
+if (typeof kpTxt !== "undefined") kpTxt.visible = false;
+if (typeof healthTxt !== "undefined") healthTxt.visible = false;
+if (typeof waveTxt !== "undefined") waveTxt.visible = false;
+if (typeof nextWaveBtn !== "undefined") nextWaveBtn.visible = false;
 // Show gameplay UI when game starts
 function showGameplayUI() {
 	kpTxt.visible = true;
 	healthTxt.visible = true;