The idea is an obvious one, you'd think: make a Batman game where you act like Batman. Except, looking at the history of Batman games, it doesn't appear to have occurred to anyone else. Like, ever.
Batman as a fighter. Batman as a platformer. Even Batman as a surrealistic isometric adventure. They all capture bits of the Caped Crusader, sure - hell, even the surrealistic one - but it's not the whole picture.
Arkham Asylum, created by London's Rocksteady Studios, mixes the three together and puts them in the BioShock-esque closed setting of the titular Asylum. The idea is that the Joker and his hundreds of goons - plus assorted other supervillains - have taken over, and Batman must bring all his talents to bear to stop them.