Colostle is a solo RPG rulebook that allows you to play a single player adventure campaign through the impossible and incredible world of the Colostle. The Colostle is a castle so big that there are oceans, mountains and cities within its rooms! There is no 'outside' to the Colostle, everything is within. And stalking these Roomlands, are the Rooks, huge walking stone castle towers that attack anything they see, but hold the Rookstones, the only source of magic in this world.