===================================================================
--- original.js
+++ change.js
@@ -1,6 +1,437 @@
-/****
+/**** 
+* Plugins
+****/ 
+var tween = LK.import("@upit/tween.v1");
+
+/**** 
+* Classes
+****/ 
+// Bullet class
+var Bullet = Container.expand(function () {
+	var self = Container.call(this);
+	var bulletGfx = self.attachAsset('bullet', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.dx = 0;
+	self.dy = 0;
+	self.damage = 1;
+	self.lifetime = 60; // ticks
+	self.update = function () {
+		self.x += self.dx;
+		self.y += self.dy;
+		self.lifetime--;
+		if (self.lifetime <= 0) {
+			self.destroy();
+		}
+	};
+	return self;
+});
+// Enemy class
+var Enemy = Container.expand(function () {
+	var self = Container.call(this);
+	var enemyGfx = self.attachAsset('enemyUnit', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.hp = 2 + wave;
+	self.speed = 2 + 0.2 * wave;
+	self.targetX = commandCenterPos.x;
+	self.targetY = commandCenterPos.y;
+	self.reward = 10 + 2 * wave;
+	self.update = function () {
+		var dx = self.targetX - self.x;
+		var dy = self.targetY - self.y;
+		var dist = Math.sqrt(dx * dx + dy * dy);
+		if (dist > 2) {
+			self.x += dx / dist * self.speed;
+			self.y += dy / dist * self.speed;
+		}
+	};
+	return self;
+});
+// Turret class
+var Turret = Container.expand(function () {
+	var self = Container.call(this);
+	// Attach base
+	var base = self.attachAsset('turretBase', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	// Attach barrel
+	var barrel = self.attachAsset('turretBarrel', {
+		anchorX: 0.5,
+		anchorY: 0.85,
+		y: -30
+	});
+	self.level = 1;
+	self.fireRate = 60; // ticks between shots
+	self.lastShot = 0;
+	self.range = 500;
+	self.damage = 1;
+	self.upgrade = function () {
+		if (self.level < 3) {
+			self.level += 1;
+			self.fireRate = Math.max(30, self.fireRate - 10);
+			self.range += 80;
+			self.damage += 1;
+			// Animate upgrade
+			tween(self, {
+				scaleX: 1.2,
+				scaleY: 1.2
+			}, {
+				duration: 120,
+				easing: tween.easeOut,
+				onFinish: function onFinish() {
+					tween(self, {
+						scaleX: 1,
+						scaleY: 1
+					}, {
+						duration: 120,
+						easing: tween.easeIn
+					});
+				}
+			});
+		}
+	};
+	// Find nearest enemy in range
+	self.findTarget = function () {
+		var minDist = self.range;
+		var target = null;
+		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 < minDist) {
+				minDist = dist;
+				target = e;
+			}
+		}
+		return target;
+	};
+	// Called every tick
+	self.update = function () {
+		// Find target
+		var target = self.findTarget();
+		if (target) {
+			// Rotate barrel towards target
+			var dx = target.x - self.x;
+			var dy = target.y - self.y;
+			var angle = Math.atan2(dy, dx) - Math.PI / 2;
+			barrel.rotation = angle;
+			// Fire if ready
+			if (LK.ticks - self.lastShot >= self.fireRate) {
+				self.lastShot = LK.ticks;
+				var b = new Bullet();
+				b.x = self.x;
+				b.y = self.y;
+				b.rotation = angle + Math.PI / 2;
+				b.dx = Math.cos(angle + Math.PI / 2) * 32;
+				b.dy = Math.sin(angle + Math.PI / 2) * 32;
+				b.damage = self.damage;
+				bullets.push(b);
+				game.addChild(b);
+			}
+		}
+	};
+	// Touch to upgrade
+	self.down = function (x, y, obj) {
+		if (resources >= turretUpgradeCost(self.level)) {
+			resources -= turretUpgradeCost(self.level);
+			self.upgrade();
+			updateResourceText();
+		}
+	};
+	return self;
+});
+
+/**** 
 * Initialize Game
-****/
+****/ 
 var game = new LK.Game({
-	backgroundColor: 0x000000
-});
\ No newline at end of file
+	backgroundColor: 0x222831
+});
+
+/**** 
+* Game Code
+****/ 
+// Build button
+// Upgrade button
+// Bullet
+// Enemy unit
+// Command center
+// Turret barrel
+// Turret base
+// Game constants
+var baseWidth = 2048;
+var baseHeight = 2732;
+var commandCenterPos = {
+	x: baseWidth / 2,
+	y: baseHeight - 350
+};
+var turretSpots = [{
+	x: baseWidth / 2 - 350,
+	y: baseHeight - 700
+}, {
+	x: baseWidth / 2 + 350,
+	y: baseHeight - 700
+}, {
+	x: baseWidth / 2 - 600,
+	y: baseHeight - 1100
+}, {
+	x: baseWidth / 2 + 600,
+	y: baseHeight - 1100
+}, {
+	x: baseWidth / 2,
+	y: baseHeight - 1100
+}];
+var maxTurrets = 5;
+var turretBuildCost = 50;
+function turretUpgradeCost(level) {
+	return 40 * level;
+}
+var wave = 1;
+var enemies = [];
+var bullets = [];
+var turrets = [];
+var resources = 100;
+var commandCenterHP = 10;
+var isPlacingTurret = false;
+// Command Center
+var commandCenter = LK.getAsset('commandCenter', {
+	anchorX: 0.5,
+	anchorY: 0.5,
+	x: commandCenterPos.x,
+	y: commandCenterPos.y
+});
+game.addChild(commandCenter);
+// GUI: Resource display
+var resourceTxt = new Text2('Resources: 100', {
+	size: 80,
+	fill: "#fff"
+});
+resourceTxt.anchor.set(0.5, 0);
+LK.gui.top.addChild(resourceTxt);
+// GUI: Wave display
+var waveTxt = new Text2('Wave: 1', {
+	size: 80,
+	fill: "#fff"
+});
+waveTxt.anchor.set(0.5, 0);
+LK.gui.top.addChild(waveTxt);
+waveTxt.y = 90;
+// GUI: Command Center HP
+var hpTxt = new Text2('Base HP: 10', {
+	size: 80,
+	fill: "#fff"
+});
+hpTxt.anchor.set(0.5, 0);
+LK.gui.top.addChild(hpTxt);
+hpTxt.y = 180;
+// GUI: Build Turret Button
+var buildBtn = LK.getAsset('buildBtn', {
+	anchorX: 0.5,
+	anchorY: 0.5,
+	x: baseWidth / 2 - 250,
+	y: baseHeight - 180
+});
+var buildBtnTxt = new Text2('Build Turret\n50', {
+	size: 48,
+	fill: "#fff"
+});
+buildBtnTxt.anchor.set(0.5, 0.5);
+buildBtn.addChild(buildBtnTxt);
+game.addChild(buildBtn);
+// GUI: Upgrade All Button
+var upgradeBtn = LK.getAsset('upgradeBtn', {
+	anchorX: 0.5,
+	anchorY: 0.5,
+	x: baseWidth / 2 + 250,
+	y: baseHeight - 180
+});
+var upgradeBtnTxt = new Text2('Upgrade All', {
+	size: 48,
+	fill: "#fff"
+});
+upgradeBtnTxt.anchor.set(0.5, 0.5);
+upgradeBtn.addChild(upgradeBtnTxt);
+game.addChild(upgradeBtn);
+// Update resource text
+function updateResourceText() {
+	resourceTxt.setText('Resources: ' + resources);
+}
+function updateWaveText() {
+	waveTxt.setText('Wave: ' + wave);
+}
+function updateHPText() {
+	hpTxt.setText('Base HP: ' + commandCenterHP);
+}
+// Build turret on next available spot
+function buildTurret() {
+	if (resources < turretBuildCost) return;
+	if (turrets.length >= maxTurrets) return;
+	var spot = turretSpots[turrets.length];
+	var t = new Turret();
+	t.x = spot.x;
+	t.y = spot.y;
+	turrets.push(t);
+	game.addChild(t);
+	resources -= turretBuildCost;
+	updateResourceText();
+}
+// Upgrade all turrets
+function upgradeAllTurrets() {
+	for (var i = 0; i < turrets.length; i++) {
+		var t = turrets[i];
+		if (t.level < 3 && resources >= turretUpgradeCost(t.level)) {
+			resources -= turretUpgradeCost(t.level);
+			t.upgrade();
+		}
+	}
+	updateResourceText();
+}
+// Build button event
+buildBtn.down = function (x, y, obj) {
+	buildTurret();
+};
+// Upgrade button event
+upgradeBtn.down = function (x, y, obj) {
+	upgradeAllTurrets();
+};
+// Place initial turret
+buildTurret();
+// Enemy spawn logic
+var spawnTimer = 0;
+var enemiesToSpawn = 0;
+function startWave() {
+	enemiesToSpawn = 4 + wave * 2;
+	spawnTimer = 0;
+	updateWaveText();
+}
+startWave();
+// Main game update
+game.update = function () {
+	// Turrets update
+	for (var i = 0; i < turrets.length; i++) {
+		turrets[i].update();
+	}
+	// Bullets update
+	for (var i = bullets.length - 1; i >= 0; i--) {
+		var b = bullets[i];
+		b.update();
+		// Remove if out of bounds
+		if (b.x < -100 || b.x > baseWidth + 100 || b.y < -100 || b.y > baseHeight + 100 || b.lifetime <= 0) {
+			b.destroy();
+			bullets.splice(i, 1);
+			continue;
+		}
+		// Check collision with enemies
+		for (var j = enemies.length - 1; j >= 0; j--) {
+			var e = enemies[j];
+			if (b.intersects(e)) {
+				e.hp -= b.damage;
+				b.destroy();
+				bullets.splice(i, 1);
+				// Animate hit
+				tween(e, {
+					scaleX: 1.2,
+					scaleY: 1.2
+				}, {
+					duration: 80,
+					onFinish: function onFinish() {
+						tween(e, {
+							scaleX: 1,
+							scaleY: 1
+						}, {
+							duration: 80
+						});
+					}
+				});
+				if (e.hp <= 0) {
+					// Enemy destroyed
+					resources += e.reward;
+					updateResourceText();
+					e.destroy();
+					enemies.splice(j, 1);
+				}
+				break;
+			}
+		}
+	}
+	// Enemies update
+	for (var i = enemies.length - 1; i >= 0; i--) {
+		var e = enemies[i];
+		e.update();
+		// Check if reached command center
+		if (e.intersects(commandCenter)) {
+			commandCenterHP -= 1;
+			updateHPText();
+			// Animate base hit
+			LK.effects.flashObject(commandCenter, 0xff0000, 300);
+			e.destroy();
+			enemies.splice(i, 1);
+			if (commandCenterHP <= 0) {
+				LK.effects.flashScreen(0xff0000, 1000);
+				LK.showGameOver();
+				return;
+			}
+		}
+	}
+	// Enemy spawn
+	if (enemiesToSpawn > 0) {
+		if (spawnTimer <= 0) {
+			// Spawn enemy at random edge
+			var edge = Math.floor(Math.random() * 3);
+			var ex, ey;
+			if (edge === 0) {
+				// left
+				ex = 100;
+				ey = 600 + Math.random() * 800;
+			} else if (edge === 1) {
+				// right
+				ex = baseWidth - 100;
+				ey = 600 + Math.random() * 800;
+			} else {
+				// top
+				ex = baseWidth / 2 - 400 + Math.random() * 800;
+				ey = 100;
+			}
+			var enemy = new Enemy();
+			enemy.x = ex;
+			enemy.y = ey;
+			enemies.push(enemy);
+			game.addChild(enemy);
+			enemiesToSpawn--;
+			spawnTimer = Math.max(30, 90 - wave * 2);
+		} else {
+			spawnTimer--;
+		}
+	} else if (enemies.length === 0) {
+		// Next wave
+		wave++;
+		commandCenterHP = Math.min(10, commandCenterHP + 2);
+		updateHPText();
+		startWave();
+	}
+};
+// Touch to upgrade turrets directly
+game.down = function (x, y, obj) {
+	// Check if touch is on a turret
+	for (var i = 0; i < turrets.length; i++) {
+		var t = turrets[i];
+		var dx = x - t.x;
+		var dy = y - t.y;
+		if (dx * dx + dy * dy < 100 * 100) {
+			// Try upgrade
+			if (resources >= turretUpgradeCost(t.level) && t.level < 3) {
+				resources -= turretUpgradeCost(t.level);
+				t.upgrade();
+				updateResourceText();
+			}
+			return;
+		}
+	}
+};
+// Prevent placing elements in top left 100x100
+// (All GUI is centered or at bottom, so nothing to do here)
\ No newline at end of file