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

/**** 
* Classes
****/ 
// Car class
var Car = Container.expand(function () {
	var self = Container.call(this);
	var carSprite = self.attachAsset('car', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = carSprite.width;
	self.height = carSprite.height;
	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
	});
	// Set fixed size for all obstacles
	obsSprite.width = 200;
	obsSprite.height = 200;
	self.width = obsSprite.width;
	self.height = obsSprite.height;
	self.speed = 22; // pixels per frame, can be increased for difficulty
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// ObstacleBlack class (large, rare, black)
var ObstacleBlack = Container.expand(function () {
	var self = Container.call(this);
	var obsSprite = self.attachAsset('obstacleBlack', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	obsSprite.width = 320;
	obsSprite.height = 320;
	self.width = obsSprite.width;
	self.height = obsSprite.height;
	self.speed = 22;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// ObstaclePurple class
var ObstaclePurple = Container.expand(function () {
	var self = Container.call(this);
	var obsSprite = self.attachAsset('obstaclePurple', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	obsSprite.width = 200;
	obsSprite.height = 200;
	self.width = obsSprite.width;
	self.height = obsSprite.height;
	self.speed = 22;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});

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

/**** 
* Game Code
****/ 
// Road width: 1200px, centered
// Game area: 2048x2732
// Car asset: blue box, 200x350
// Obstacle asset: red box, 200x200
// Road lane asset: gray box, 2048x2732 (background, not used as a background, but for lane lines)
var ROAD_WIDTH = 1200;
var ROAD_LEFT = (2048 - ROAD_WIDTH) / 2;
var ROAD_RIGHT = ROAD_LEFT + ROAD_WIDTH;
var CAR_Y = 2732 - 500; // Car vertical position
// Draw lane lines (visual only)
var laneLines = [];
for (var i = 1; i < 4; i++) {
	var laneX = ROAD_LEFT + ROAD_WIDTH / 4 * i;
	for (var j = 0; j < 6; j++) {
		var line = LK.getAsset('laneLine', {
			anchorX: 0.5,
			anchorY: 0.5,
			x: laneX,
			y: j * 500 + 200,
			alpha: 0.25
		});
		game.addChild(line);
		laneLines.push(line);
	}
}
// Add left and right lane edge lines
var edgeLines = [];
for (var j = 0; j < 6; j++) {
	// Left edge (road boundary)
	var leftEdge = LK.getAsset('laneLine', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: ROAD_LEFT,
		y: j * 500 + 200,
		alpha: 0.7
	});
	game.addChild(leftEdge);
	edgeLines.push(leftEdge);
	// Right edge (road boundary)
	var rightEdge = LK.getAsset('laneLine', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: ROAD_RIGHT,
		y: j * 500 + 200,
		alpha: 0.7
	});
	game.addChild(rightEdge);
	edgeLines.push(rightEdge);
	// Far left vertical line (game border)
	var farLeft = LK.getAsset('laneLine', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 0 + 30,
		// 30px from the very left
		y: j * 500 + 200,
		alpha: 0.4
	});
	game.addChild(farLeft);
	edgeLines.push(farLeft);
	// Far right vertical line (game border)
	var farRight = LK.getAsset('laneLine', {
		anchorX: 0.5,
		anchorY: 0.5,
		x: 2048 - 30,
		// 30px from the very right
		y: j * 500 + 200,
		alpha: 0.4
	});
	game.addChild(farRight);
	edgeLines.push(farRight);
}
// Car
var car = new Car();
car.x = 2048 / 2;
car.y = CAR_Y;
game.addChild(car);
// Obstacles
var obstacles = [];
// Score
var score = 0;
var scoreTxt = new Text2('0', {
	size: 120,
	fill: "#fff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Touch controls
var dragX = null;
var dragStartCarX = null;
// Move handler
function handleMove(x, y, obj) {
	if (dragX !== null) {
		// Clamp to road
		var dx = x - dragX;
		var newCarX = dragStartCarX + dx;
		if (newCarX < ROAD_LEFT + car.width / 2) newCarX = ROAD_LEFT + car.width / 2;
		if (newCarX > ROAD_RIGHT - car.width / 2) newCarX = ROAD_RIGHT - car.width / 2;
		car.x = newCarX;
	}
	// Check collision
	for (var i = 0; i < obstacles.length; i++) {
		if (car.intersects(obstacles[i])) {
			LK.effects.flashScreen(0xff0000, 800);
			LK.showGameOver();
			return;
		}
	}
}
// Touch down
game.down = function (x, y, obj) {
	// Only allow drag if touch is on car or below
	if (y > car.y - car.height / 2 - 100) {
		dragX = x;
		dragStartCarX = car.x;
		handleMove(x, y, obj);
	}
};
// Touch up
game.up = function (x, y, obj) {
	dragX = null;
	dragStartCarX = null;
};
// Move
game.move = handleMove;
// Main update
game.update = function () {
	// Animate lane lines for road movement
	for (var i = 0; i < laneLines.length; i++) {
		laneLines[i].y += 22;
		if (laneLines[i].y > 2732 + 100) {
			laneLines[i].y -= 2732 + 400;
		}
	}
	// Animate edge lines for road movement
	for (var i = 0; i < edgeLines.length; i++) {
		edgeLines[i].y += 22;
		if (edgeLines[i].y > 2732 + 100) {
			edgeLines[i].y -= 2732 + 400;
		}
	}
	// Obstacles update
	for (var i = obstacles.length - 1; i >= 0; i--) {
		var obs = obstacles[i];
		obs.update();
		if (obs.y - obs.height / 2 > 2732 + 100) {
			// Passed, remove and score
			obs.destroy();
			obstacles.splice(i, 1);
			score += 1;
			scoreTxt.setText(score);
		} else if (car.intersects(obs)) {
			LK.effects.flashScreen(0xff0000, 800);
			LK.showGameOver();
			return;
		}
	}
	// --- Dynamic difficulty: obstacle speed and spawn rate scale with score ---
	// Calculate difficulty scaling
	var minSpawnInterval = 12; // minimum ticks between spawns (faster = more obstacles)
	var maxSpawnInterval = 40; // slowest spawn interval (start)
	var spawnInterval = Math.floor(maxSpawnInterval - Math.min(score, 60) * 0.4); // gets faster with score, clamps at min
	if (spawnInterval < minSpawnInterval) spawnInterval = minSpawnInterval;
	// Calculate speed scaling
	var baseSpeed = 22;
	var maxSpeed = 60;
	var speed = baseSpeed + Math.min(score, 100) * 0.35; // up to maxSpeed
	if (speed > maxSpeed) speed = maxSpeed;
	// Update all obstacle speeds to match current difficulty
	for (var i = 0; i < obstacles.length; i++) {
		obstacles[i].speed = speed;
	}
	// Also update lane line and edge line speeds for road movement
	for (var i = 0; i < laneLines.length; i++) {
		laneLines[i].y += speed;
		if (laneLines[i].y > 2732 + 100) {
			laneLines[i].y -= 2732 + 400;
		}
	}
	for (var i = 0; i < edgeLines.length; i++) {
		edgeLines[i].y += speed;
		if (edgeLines[i].y > 2732 + 100) {
			edgeLines[i].y -= 2732 + 400;
		}
	}
	// Spawn new obstacles
	if (LK.ticks % spawnInterval === 0) {
		// Random lane: 4 lanes
		var lane = Math.floor(Math.random() * 4);
		var laneCenter = ROAD_LEFT + ROAD_WIDTH / 8 + lane * (ROAD_WIDTH / 4);
		// 7% black, 18% big red (removed), 30% normal, 45% purple
		var obs;
		var r = Math.random();
		if (r < 0.07) {
			obs = new ObstacleBlack();
		} else if (r < 0.37) {
			obs = new Obstacle();
		} else {
			obs = new ObstaclePurple();
		}
		obs.x = laneCenter;
		obs.y = -obs.height / 2;
		obs.speed = speed; // set initial speed
		game.addChild(obs);
		obstacles.push(obs);
	}
};

===================================================================
--- original.js
+++ change.js
@@ -79,19 +79,8 @@
 
 /**** 
 * Game Code
 ****/ 
-// Add background image (full screen, behind all elements)
-var background = LK.getAsset('obstaclePurple', {
-	anchorX: 0.5,
-	anchorY: 0.5,
-	x: 2048 / 2,
-	y: 2732 / 2,
-	width: 2048,
-	height: 2732,
-	alpha: 0.18 // subtle, not too strong
-});
-game.addChild(background);
 // Road width: 1200px, centered
 // Game area: 2048x2732
 // Car asset: blue box, 200x350
 // Obstacle asset: red box, 200x200