public void update(Map map, Snake[] snakes, double dt) {
		realX += Snake.xOffset(heading) * SPEED * dt;
		realY += Snake.yOffset(heading) * SPEED * dt;
		if (!map.passable(tileX(), tileY())) {
			finished = true;
			return;
		}
		for (Snake s : snakes) {
			if (s.hit(tileX(), tileY())) {
				finished = true;
				return;
			}
		}
	}