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.
Obviously enough, this can involve just punching the bleeding daylights out of people: Batman's highly-honed martial art prowess is simulated by your ability to chain attacks between thugs. The problems build when these thugs have weapons. Knives are one thing - your cloak can be used to stun before delivering pummelage - but when gunpowder enters the scene, Batman leaves it.
Since he doesn't use such cowardly weapons himself, this leads to the second part of the game: stealth. Except that's a somewhat dirty word for the developer, who much prefers the phrase 'Predator'. This isn't about you being weak. This is about you picking a group of thugs one by one until they're all quivering in fear - a behaviour built into the AI system.
Guards will group to guard each other, descend into panic and blindfire. As well as batarangs and gliding kicks, highly distinctive tricks are available, such as grabbing someone passing beneath you and stringing them up. And once they're dangling, you can cut the rope and use them as a trap.
Alternating between stealthy violence and unstealthy violence isn't the full extent of Batman though. He's also The World's Greatest Detective (I object - Sherlock Holmes) (Me too! - Poirot) (And Me! - Jennifer Fletcher). The point being, you can enter an investigative mode, which turns the world into CSI o-vision, and brings everything from fingerprints to your opponent's weapons into focus. The latter is useful when planning who to take down first, but the former leads into puzzle-solving. Once you've identified who a set of fingerprints belong to, you can follow them - an 'evidence trail'.
Asylum also thoroughly explores such superhero tropes as the deathtrap - providing a real in-game justification for puzzles. And attention has been paid the Joker, who takes a similar role to BioShock's Andrew Ryan or SHODAN (System Shock), baiting and mocking you every step of the way.
In short, if Arkham Asylum is able to pull these disparate elements together, we could end up with one of the best superhero games of all time. Gotham's a dark city, but ironically, this looks like it's got a bright future.