===================================================================
--- original.js
+++ change.js
@@ -1,6 +1,194 @@
-/****
+/**** 
+* Plugins
+****/ 
+var tween = LK.import("@upit/tween.v1");
+
+/**** 
+* Classes
+****/ 
+var Collectible = Container.expand(function (isLightWorld) {
+	var self = Container.call(this);
+	self.isLightWorld = isLightWorld;
+	var collectibleGraphics = self.attachAsset(isLightWorld ? 'lightCollectible' : 'darkCollectible', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.speed = -8;
+	self.collected = false;
+	self.update = function () {
+		self.x += self.speed;
+		collectibleGraphics.rotation += 0.1;
+	};
+	return self;
+});
+var Obstacle = Container.expand(function (isLightWorld) {
+	var self = Container.call(this);
+	self.isLightWorld = isLightWorld;
+	var obstacleGraphics = self.attachAsset(isLightWorld ? 'lightObstacle' : 'darkObstacle', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.speed = -8;
+	self.update = function () {
+		self.x += self.speed;
+	};
+	return self;
+});
+var Player = Container.expand(function () {
+	var self = Container.call(this);
+	var playerGraphics = self.attachAsset('player', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.verticalSpeed = 0;
+	self.gravity = 0.5;
+	self.jumpPower = -12;
+	self.isGrounded = false;
+	return self;
+});
+
+/**** 
 * Initialize Game
-****/
+****/ 
 var game = new LK.Game({
-	backgroundColor: 0x000000
-});
\ No newline at end of file
+	backgroundColor: 0x87CEEB
+});
+
+/**** 
+* Game Code
+****/ 
+var isLightWorld = true;
+var player = null;
+var obstacles = [];
+var collectibles = [];
+var gameSpeed = 8;
+var spawnTimer = 0;
+var groundY = 2200;
+var lastSpawnX = 2200;
+var scoreTxt = new Text2('Score: 0', {
+	size: 80,
+	fill: 0xFFFFFF
+});
+scoreTxt.anchor.set(0.5, 0);
+LK.gui.top.addChild(scoreTxt);
+var worldIndicator = new Text2('Light World', {
+	size: 60,
+	fill: 0xFFD700
+});
+worldIndicator.anchor.set(0.5, 1);
+LK.gui.bottom.addChild(worldIndicator);
+function updateWorldVisuals() {
+	if (isLightWorld) {
+		game.setBackgroundColor(0x87CEEB);
+		worldIndicator.setText('Light World');
+		worldIndicator.style.fill = "#FFD700";
+	} else {
+		game.setBackgroundColor(0x2C1810);
+		worldIndicator.setText('Dark World');
+		worldIndicator.style.fill = "#9C27B0";
+	}
+	tween(game, {}, {
+		duration: 200,
+		onFinish: function onFinish() {
+			for (var i = 0; i < obstacles.length; i++) {
+				var obstacle = obstacles[i];
+				obstacle.alpha = obstacle.isLightWorld === isLightWorld ? 1 : 0.3;
+			}
+			for (var j = 0; j < collectibles.length; j++) {
+				var collectible = collectibles[j];
+				collectible.alpha = collectible.isLightWorld === isLightWorld ? 1 : 0.3;
+			}
+		}
+	});
+}
+function spawnObstacle() {
+	var worldType = Math.random() < 0.5;
+	var obstacle = new Obstacle(worldType);
+	obstacle.x = 2200;
+	obstacle.y = groundY - 50;
+	obstacle.alpha = obstacle.isLightWorld === isLightWorld ? 1 : 0.3;
+	obstacles.push(obstacle);
+	game.addChild(obstacle);
+}
+function spawnCollectible() {
+	var worldType = Math.random() < 0.5;
+	var collectible = new Collectible(worldType);
+	collectible.x = 2200;
+	collectible.y = groundY - Math.random() * 300 - 100;
+	collectible.alpha = collectible.isLightWorld === isLightWorld ? 1 : 0.3;
+	collectibles.push(collectible);
+	game.addChild(collectible);
+}
+player = game.addChild(new Player());
+player.x = 400;
+player.y = groundY - 40;
+updateWorldVisuals();
+game.down = function (x, y, obj) {
+	isLightWorld = !isLightWorld;
+	updateWorldVisuals();
+	LK.getSound('flip').play();
+	if (player.isGrounded) {
+		player.verticalSpeed = player.jumpPower;
+		player.isGrounded = false;
+	}
+};
+game.update = function () {
+	if (!player) return;
+	player.verticalSpeed += player.gravity;
+	player.y += player.verticalSpeed;
+	if (player.y >= groundY - 40) {
+		player.y = groundY - 40;
+		player.verticalSpeed = 0;
+		player.isGrounded = true;
+	}
+	spawnTimer += 1;
+	gameSpeed = Math.min(12, 8 + LK.getScore() / 100);
+	if (spawnTimer % Math.max(60, 120 - LK.getScore()) === 0) {
+		if (Math.random() < 0.7) {
+			spawnObstacle();
+		} else {
+			spawnCollectible();
+		}
+	}
+	for (var i = obstacles.length - 1; i >= 0; i--) {
+		var obstacle = obstacles[i];
+		obstacle.speed = -gameSpeed;
+		if (obstacle.x < -100) {
+			obstacle.destroy();
+			obstacles.splice(i, 1);
+			continue;
+		}
+		if (obstacle.isLightWorld === isLightWorld && player.intersects(obstacle)) {
+			LK.getSound('hit').play();
+			LK.effects.flashScreen(0xff0000, 1000);
+			LK.showGameOver();
+			return;
+		}
+	}
+	for (var j = collectibles.length - 1; j >= 0; j--) {
+		var collectible = collectibles[j];
+		collectible.speed = -gameSpeed;
+		if (collectible.x < -100) {
+			collectible.destroy();
+			collectibles.splice(j, 1);
+			continue;
+		}
+		if (!collectible.collected && collectible.isLightWorld === isLightWorld && player.intersects(collectible)) {
+			collectible.collected = true;
+			LK.setScore(LK.getScore() + 10);
+			scoreTxt.setText('Score: ' + LK.getScore());
+			LK.getSound('collect').play();
+			tween(collectible, {
+				alpha: 0,
+				scaleX: 2,
+				scaleY: 2
+			}, {
+				duration: 300,
+				onFinish: function onFinish() {
+					collectible.destroy();
+				}
+			});
+			collectibles.splice(j, 1);
+		}
+	}
+};
\ No newline at end of file