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

/**** 
* Classes
****/ 
// Barrier (obstacle)
var Barrier = Container.expand(function () {
	var self = Container.call(this);
	var barrierSprite = self.attachAsset('barrier', {
		anchorX: 0.5,
		anchorY: 1
	});
	self.width = barrierSprite.width;
	self.height = barrierSprite.height;
	self.speed = 0; // Will be set by game
	// Called every tick
	self.update = function () {
		self.x -= self.speed;
	};
	return self;
});
// PrintableBlock (special printable barrier)
var PrintableBlock = Container.expand(function () {
	var self = Container.call(this);
	var blockSprite = self.attachAsset('barrier', {
		anchorX: 0.5,
		anchorY: 1
	});
	self.width = blockSprite.width;
	self.height = blockSprite.height;
	self.speed = 0; // Will be set by game
	// Optionally, visually distinguish printable blocks (e.g. by color)
	blockSprite.color = 0x27ae60; // greenish, but engine may ignore this
	// Called every tick
	self.update = function () {
		self.x -= self.speed;
	};
	return self;
});
// Runner (player character)
var Runner = Container.expand(function () {
	var self = Container.call(this);
	var runnerSprite = self.attachAsset('runner', {
		anchorX: 0.5,
		anchorY: 1
	});
	self.width = runnerSprite.width;
	self.height = runnerSprite.height;
	self.groundY = 0; // Will be set after ground is created
	self.isJumping = false;
	self.jumpStartY = 0;
	self.jumpStartTime = 0;
	self.jumpDuration = 0;
	self.jumpHeight = 0;
	self.velocityY = 0;
	// Physics
	self.gravity = 1.2; // px per tick^2 (reduced for slower fall)
	self.jumpVelocity = -52; // px per tick (negative is up)
	// Called every tick
	self.update = function () {
		// If jumping, apply velocity
		if (self.isJumping) {
			self.y += self.velocityY;
			self.velocityY += self.gravity;
			// Landed
			if (self.y >= self.groundY) {
				self.y = self.groundY;
				self.isJumping = false;
				self.velocityY = 0;
			}
		}
	};
	// Start jump
	self.jump = function () {
		if (!self.isJumping) {
			self.isJumping = true;
			self.velocityY = self.jumpVelocity;
		}
	};
	// Cancel jump (for variable jump height)
	self.cancelJump = function () {
		if (self.isJumping && self.velocityY < -18) {
			self.velocityY = -18;
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x0a0a2a
});

/**** 
* Game Code
****/ 
// Pixel starry night background
var backgroundStars = [];
var BG_STAR_SCROLL_SPEED = 1.2; // slower for parallax
var BG_STAR_LAYERS = 3;
var BG_STARS_PER_LAYER = [32, 24, 16]; // more in front, less in back
var BG_STAR_COLORS = [0xffffff,
// white
0xcce6ff,
// blueish
0xfff6cc,
// yellowish
0xffcccc,
// reddish
0xb0b0ff // purple/blue
];
var BG_STAR_SIZES = [6, 10, 16]; // back, mid, front
function createBackgroundStars() {
	for (var layer = 0; layer < BG_STAR_LAYERS; layer++) {
		var count = BG_STARS_PER_LAYER[layer];
		var size = BG_STAR_SIZES[layer];
		for (var i = 0; i < count; i++) {
			var color = BG_STAR_COLORS[Math.floor(Math.random() * BG_STAR_COLORS.length)];
			var star = LK.getAsset('ground', {
				anchorX: 0.5,
				anchorY: 0.5,
				width: size + Math.floor(Math.random() * 2),
				height: size + Math.floor(Math.random() * 2),
				x: Math.floor(Math.random() * 2048),
				y: Math.floor(Math.random() * 2200)
			});
			star.tint = color;
			// Twinkle: randomize alpha, and store twinkle params
			star.alpha = 0.7 + Math.random() * 0.3;
			star._twinkleSpeed = 0.008 + Math.random() * 0.012 + layer * 0.004;
			star._twinklePhase = Math.random() * Math.PI * 2;
			star._starLayer = layer;
			backgroundStars.push(star);
			game.addChild(star);
		}
	}
}
createBackgroundStars();
function updateBackgroundStars() {
	for (var i = 0; i < backgroundStars.length; i++) {
		var star = backgroundStars[i];
		// Parallax: slower for further layers
		var speed = BG_STAR_SCROLL_SPEED * (0.5 + 0.5 * (BG_STAR_LAYERS - star._starLayer) / BG_STAR_LAYERS);
		star.x -= speed;
		// Twinkle
		star.alpha = 0.7 + 0.3 * Math.sin(LK.ticks * star._twinkleSpeed + star._twinklePhase);
		// Wrap around
		if (star.x < -star.width) {
			star.x = 2048 + Math.random() * 80;
			star.y = Math.floor(Math.random() * 2200);
			// Optionally randomize color and twinkle
			star.tint = BG_STAR_COLORS[Math.floor(Math.random() * BG_STAR_COLORS.length)];
			star._twinkleSpeed = 0.008 + Math.random() * 0.012 + star._starLayer * 0.004;
			star._twinklePhase = Math.random() * Math.PI * 2;
		}
	}
}
// Game constants
var GROUND_Y = 2200; // y position of ground top
var RUNNER_START_X = 400;
var BARRIER_MIN_GAP = 600;
var BARRIER_MAX_GAP = 950;
var BARRIER_MIN_HEIGHT = 180;
var BARRIER_MAX_HEIGHT = 320;
var BARRIER_WIDTH = 80;
var SCROLL_START_SPEED = 13;
var SCROLL_MAX_SPEED = 24;
var SCROLL_ACCEL = 0.018; // px per tick^2
// Character (costume) options
var CHARACTER_OPTIONS = [{
	id: 'runner',
	color: 0x2d9cdb
},
// blue
{
	id: 'runner',
	color: 0xe67e22
},
// orange
{
	id: 'runner',
	color: 0x27ae60
},
// green
{
	id: 'runner',
	color: 0x8e44ad
} // purple
];
var selectedCharacterIndex = 0;
// Game state
var runner = null;
var ground = null;
var barriers = [];
var score = 0;
var scrollSpeed = SCROLL_START_SPEED;
var lastBarrierX = 0;
var isGameOver = false;
var isTouching = false;
// Menu state
var isMenuOpen = true;
var menuContainer = null;
var costumeContainer = null;
// Score display
var scoreTxt = new Text2('0', {
	size: 140,
	fill: 0xFFFFFF
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Dash button UI
var dashBtn = LK.getAsset('barrier', {
	anchorX: 0.5,
	anchorY: 0.5,
	width: 320,
	height: 160,
	x: 2048 - 240,
	y: 2732 - 220
});
dashBtn.tint = 0x2d9cdb;
var dashTxt = new Text2('DASH', {
	size: 80,
	fill: 0xffffff
});
dashTxt.anchor.set(0.5, 0.5);
dashTxt.x = dashBtn.x;
dashTxt.y = dashBtn.y;
LK.gui.addChild(dashBtn);
LK.gui.addChild(dashTxt);
// Dash state
var dashActive = false;
var dashCooldown = false;
var dashDuration = 32; // frames (about 0.5s)
var dashCooldownTime = 90; // frames (about 1.5s)
var dashTimer = 0;
var dashCooldownTimer = 0;
// Dash button event
dashBtn.down = function (x, y, obj) {
	if (isMenuOpen || isGameOver) return;
	if (!dashActive && !dashCooldown) {
		dashActive = true;
		dashTimer = dashDuration;
		dashCooldown = false;
		dashBtn.alpha = 0.5;
		dashTxt.alpha = 0.5;
	}
};
dashTxt.down = dashBtn.down;
// Create ground
ground = LK.getAsset('ground', {
	anchorX: 0,
	anchorY: 0,
	x: 0,
	y: GROUND_Y
});
game.addChild(ground);
// Create runner (with selected costume)
function createRunnerWithCostume() {
	var costume = CHARACTER_OPTIONS[selectedCharacterIndex];
	var r = new Runner();
	// Set color if possible
	if (r.children && r.children[0]) {
		r.children[0].tint = costume.color;
	}
	r.x = RUNNER_START_X;
	r.groundY = GROUND_Y;
	r.y = GROUND_Y;
	return r;
}
runner = createRunnerWithCostume();
game.addChild(runner);
// Menu UI
function showMenu() {
	isMenuOpen = true;
	if (menuContainer) {
		menuContainer.visible = true;
		return;
	}
	menuContainer = new Container();
	// Background overlay
	var overlay = LK.getAsset('ground', {
		anchorX: 0,
		anchorY: 0,
		x: 0,
		y: 0,
		width: 2048,
		height: 2732
	});
	overlay.alpha = 0.85;
	menuContainer.addChild(overlay);
	// Title
	var title = new Text2('Endless Runner', {
		size: 180,
		fill: 0xffffff
	});
	title.anchor.set(0.5, 0);
	title.x = 2048 / 2;
	title.y = 400;
	menuContainer.addChild(title);
	// Play button
	var playBtn = LK.getAsset('barrier', {
		anchorX: 0.5,
		anchorY: 0.5,
		width: 500,
		height: 180,
		x: 2048 / 2,
		y: 900
	});
	playBtn.tint = 0x27ae60;
	menuContainer.addChild(playBtn);
	var playTxt = new Text2('PLAY', {
		size: 120,
		fill: 0xffffff
	});
	playTxt.anchor.set(0.5, 0.5);
	playTxt.x = playBtn.x;
	playTxt.y = playBtn.y;
	menuContainer.addChild(playTxt);
	// Color button
	var colorBtn = LK.getAsset('barrier', {
		anchorX: 0.5,
		anchorY: 0.5,
		width: 500,
		height: 180,
		x: 2048 / 2,
		y: 1200
	});
	colorBtn.tint = 0x2980b9;
	menuContainer.addChild(colorBtn);
	var colorTxt = new Text2('COLOR', {
		size: 100,
		fill: 0xffffff
	});
	colorTxt.anchor.set(0.5, 0.5);
	colorTxt.x = colorBtn.x;
	colorTxt.y = colorBtn.y;
	menuContainer.addChild(colorTxt);
	// Play button event
	playBtn.down = function (x, y, obj) {
		hideMenu();
		startGame();
	};
	playTxt.down = playBtn.down;
	// Color button event
	colorBtn.down = function (x, y, obj) {
		showCostumeMenu();
	};
	colorTxt.down = colorBtn.down;
	game.addChild(menuContainer);
}
function hideMenu() {
	isMenuOpen = false;
	if (menuContainer) menuContainer.visible = false;
	if (costumeContainer) costumeContainer.visible = false;
}
function showCostumeMenu() {
	if (!costumeContainer) {
		costumeContainer = new Container();
		// Overlay
		var overlay = LK.getAsset('ground', {
			anchorX: 0,
			anchorY: 0,
			x: 0,
			y: 0,
			width: 2048,
			height: 2732
		});
		overlay.alpha = 0.85;
		costumeContainer.addChild(overlay);
		// Title
		var title = new Text2('Select Costume', {
			size: 150,
			fill: 0xffffff
		});
		title.anchor.set(0.5, 0);
		title.x = 2048 / 2;
		title.y = 400;
		costumeContainer.addChild(title);
		// Costume preview
		var preview = LK.getAsset('runner', {
			anchorX: 0.5,
			anchorY: 1,
			x: 2048 / 2,
			y: 1200,
			width: 300,
			height: 300
		});
		preview.tint = CHARACTER_OPTIONS[selectedCharacterIndex].color;
		costumeContainer.addChild(preview);
		// Left arrow
		var leftBtn = LK.getAsset('barrier', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: 120,
			height: 120,
			x: 2048 / 2 - 250,
			y: 1200
		});
		leftBtn.tint = 0x888888;
		costumeContainer.addChild(leftBtn);
		var leftTxt = new Text2('<', {
			size: 120,
			fill: 0xffffff
		});
		leftTxt.anchor.set(0.5, 0.5);
		leftTxt.x = leftBtn.x;
		leftTxt.y = leftBtn.y;
		costumeContainer.addChild(leftTxt);
		// Right arrow
		var rightBtn = LK.getAsset('barrier', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: 120,
			height: 120,
			x: 2048 / 2 + 250,
			y: 1200
		});
		rightBtn.tint = 0x888888;
		costumeContainer.addChild(rightBtn);
		var rightTxt = new Text2('>', {
			size: 120,
			fill: 0xffffff
		});
		rightTxt.anchor.set(0.5, 0.5);
		rightTxt.x = rightBtn.x;
		rightTxt.y = rightBtn.y;
		costumeContainer.addChild(rightTxt);
		// Select button
		var selectBtn = LK.getAsset('barrier', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: 400,
			height: 140,
			x: 2048 / 2,
			y: 1700
		});
		selectBtn.tint = 0x27ae60;
		costumeContainer.addChild(selectBtn);
		var selectTxt = new Text2('SELECT', {
			size: 90,
			fill: 0xffffff
		});
		selectTxt.anchor.set(0.5, 0.5);
		selectTxt.x = selectBtn.x;
		selectTxt.y = selectBtn.y;
		costumeContainer.addChild(selectTxt);
		// Arrow events
		leftBtn.down = function (x, y, obj) {
			selectedCharacterIndex = (selectedCharacterIndex + CHARACTER_OPTIONS.length - 1) % CHARACTER_OPTIONS.length;
			preview.tint = CHARACTER_OPTIONS[selectedCharacterIndex].color;
		};
		leftTxt.down = leftBtn.down;
		rightBtn.down = function (x, y, obj) {
			selectedCharacterIndex = (selectedCharacterIndex + 1) % CHARACTER_OPTIONS.length;
			preview.tint = CHARACTER_OPTIONS[selectedCharacterIndex].color;
		};
		rightTxt.down = rightBtn.down;
		// Select event
		selectBtn.down = function (x, y, obj) {
			if (runner) {
				runner.destroy();
			}
			runner = createRunnerWithCostume();
			game.addChild(runner);
			costumeContainer.visible = false;
			menuContainer.visible = true;
		};
		selectTxt.down = selectBtn.down;
		game.addChild(costumeContainer);
	} else {
		// Update preview
		var preview = costumeContainer.children[2];
		preview.tint = CHARACTER_OPTIONS[selectedCharacterIndex].color;
		costumeContainer.visible = true;
	}
	if (menuContainer) menuContainer.visible = false;
}
// Start game from menu
function startGame() {
	hideMenu();
	resetGame();
}
// Show menu on load
showMenu();
// Helper: spawn a barrier at x
function spawnBarrier(x) {
	// 25% chance to spawn a PrintableBlock instead of a Barrier
	var isPrintable = Math.random() < 0.25;
	var barrier;
	if (isPrintable) {
		barrier = new PrintableBlock();
	} else {
		barrier = new Barrier();
	}
	barrier.x = x;
	// Randomize height
	var h = BARRIER_MIN_HEIGHT + Math.floor(Math.random() * (BARRIER_MAX_HEIGHT - BARRIER_MIN_HEIGHT + 1));
	barrier.height = h;
	barrier.children[0].height = h;
	barrier.y = GROUND_Y;
	barrier.speed = scrollSpeed;
	barriers.push(barrier);
	game.addChild(barrier);
}
// Helper: reset game state
function resetGame() {
	// Remove barriers
	for (var i = 0; i < barriers.length; i++) {
		barriers[i].destroy();
	}
	barriers = [];
	score = 0;
	scrollSpeed = SCROLL_START_SPEED;
	lastBarrierX = 1400;
	isGameOver = false;
	runner.x = RUNNER_START_X;
	runner.y = GROUND_Y;
	runner.isJumping = false;
	runner.velocityY = 0;
	scoreTxt.setText('0');
	// Spawn initial barriers
	for (var i = 0; i < 3; i++) {
		var gap = BARRIER_MIN_GAP + Math.floor(Math.random() * (BARRIER_MAX_GAP - BARRIER_MIN_GAP + 1));
		lastBarrierX += gap;
		spawnBarrier(lastBarrierX);
	}
}
// Start game
resetGame();
// Touch/press to jump
game.down = function (x, y, obj) {
	if (isMenuOpen || isGameOver) return;
	isTouching = true;
	runner.jump();
};
// Release to cut jump short
game.up = function (x, y, obj) {
	if (isMenuOpen || isGameOver) return;
	isTouching = false;
	runner.cancelJump();
};
// Main update loop
game.update = function () {
	if (isMenuOpen || isGameOver) return;
	updateBackgroundStars();
	// Dash logic
	if (dashActive) {
		// Temporarily boost scroll speed
		scrollSpeed += 13;
		dashTimer--;
		if (dashTimer <= 0) {
			dashActive = false;
			dashCooldown = true;
			dashCooldownTimer = dashCooldownTime;
			dashBtn.alpha = 0.3;
			dashTxt.alpha = 0.3;
		}
	} else if (dashCooldown) {
		dashCooldownTimer--;
		if (dashCooldownTimer <= 0) {
			dashCooldown = false;
			dashBtn.alpha = 1;
			dashTxt.alpha = 1;
		}
	}
	// Accelerate scroll speed
	if (scrollSpeed < SCROLL_MAX_SPEED) {
		scrollSpeed += SCROLL_ACCEL;
		if (scrollSpeed > SCROLL_MAX_SPEED) scrollSpeed = SCROLL_MAX_SPEED;
	}
	// Update runner
	runner.update();
	// Update barriers
	for (var i = barriers.length - 1; i >= 0; i--) {
		var barrier = barriers[i];
		barrier.speed = scrollSpeed;
		barrier.update();
		// Passed barrier
		if (!barrier.passed && barrier.x + BARRIER_WIDTH / 2 < runner.x - runner.width / 2) {
			barrier.passed = true;
			score += 1;
			scoreTxt.setText(score + '');
			LK.setScore(score);
		}
		// Remove off-screen barriers
		if (barrier.x < -BARRIER_WIDTH) {
			barrier.destroy();
			barriers.splice(i, 1);
		}
	}
	// Spawn new barriers
	if (barriers.length === 0 || barriers[barriers.length - 1].x < 2048 - BARRIER_MAX_GAP) {
		var gap = BARRIER_MIN_GAP + Math.floor(Math.random() * (BARRIER_MAX_GAP - BARRIER_MIN_GAP + 1));
		var newX = 2048 + gap;
		spawnBarrier(newX);
	}
	// Collision detection
	for (var i = 0; i < barriers.length; i++) {
		var barrier = barriers[i];
		if (runner.intersects(barrier)) {
			// Game over
			isGameOver = true;
			LK.effects.flashScreen(0xff0000, 800);
			LK.showGameOver();
			return;
		}
	}
};
// On game over, reset state for next run
LK.on('gameover', function () {
	showMenu();
});
// Prevent elements in top left 100x100
// (All elements are placed away from this area by design)

===================================================================
--- original.js
+++ change.js
@@ -212,8 +212,46 @@
 	fill: 0xFFFFFF
 });
 scoreTxt.anchor.set(0.5, 0);
 LK.gui.top.addChild(scoreTxt);
+// Dash button UI
+var dashBtn = LK.getAsset('barrier', {
+	anchorX: 0.5,
+	anchorY: 0.5,
+	width: 320,
+	height: 160,
+	x: 2048 - 240,
+	y: 2732 - 220
+});
+dashBtn.tint = 0x2d9cdb;
+var dashTxt = new Text2('DASH', {
+	size: 80,
+	fill: 0xffffff
+});
+dashTxt.anchor.set(0.5, 0.5);
+dashTxt.x = dashBtn.x;
+dashTxt.y = dashBtn.y;
+LK.gui.addChild(dashBtn);
+LK.gui.addChild(dashTxt);
+// Dash state
+var dashActive = false;
+var dashCooldown = false;
+var dashDuration = 32; // frames (about 0.5s)
+var dashCooldownTime = 90; // frames (about 1.5s)
+var dashTimer = 0;
+var dashCooldownTimer = 0;
+// Dash button event
+dashBtn.down = function (x, y, obj) {
+	if (isMenuOpen || isGameOver) return;
+	if (!dashActive && !dashCooldown) {
+		dashActive = true;
+		dashTimer = dashDuration;
+		dashCooldown = false;
+		dashBtn.alpha = 0.5;
+		dashTxt.alpha = 0.5;
+	}
+};
+dashTxt.down = dashBtn.down;
 // Create ground
 ground = LK.getAsset('ground', {
 	anchorX: 0,
 	anchorY: 0,
@@ -509,8 +547,28 @@
 // Main update loop
 game.update = function () {
 	if (isMenuOpen || isGameOver) return;
 	updateBackgroundStars();
+	// Dash logic
+	if (dashActive) {
+		// Temporarily boost scroll speed
+		scrollSpeed += 13;
+		dashTimer--;
+		if (dashTimer <= 0) {
+			dashActive = false;
+			dashCooldown = true;
+			dashCooldownTimer = dashCooldownTime;
+			dashBtn.alpha = 0.3;
+			dashTxt.alpha = 0.3;
+		}
+	} else if (dashCooldown) {
+		dashCooldownTimer--;
+		if (dashCooldownTimer <= 0) {
+			dashCooldown = false;
+			dashBtn.alpha = 1;
+			dashTxt.alpha = 1;
+		}
+	}
 	// Accelerate scroll speed
 	if (scrollSpeed < SCROLL_MAX_SPEED) {
 		scrollSpeed += SCROLL_ACCEL;
 		if (scrollSpeed > SCROLL_MAX_SPEED) scrollSpeed = SCROLL_MAX_SPEED;