it uses a modified version of Chaosium's Basic Roleplaying system. mostly it's the call of Cthulhu with the player characters being a little bit stronger because they having given some laundry training, and a complete overhaul of the magic system to reflect that magic can be cast by computers. Also the book itself is in canon as there are notes that Bob has scribbled periodically in order to make sure there isn't any dangerously accurate Cthulhu mythos knowledge in the book. this is not surprising because Charles Stross started his career designing monsters for AD&D first edition in the magazine White Dwarf. if you wish to purchase the game you can buy a PDF version of it here. <a href="http://rpg.drivethrustuff.com/product/83956/The-Laundry-RPG?cPath=8376" rel="nofollow">http://rpg.drivethrustuff.com/product/83956/The-Laundry-RPG?cPath=8376</a>
