Batman: Arkham Asylum is a paradigm of focused design that is as remarkable for what it leaves out as for the wealth of gameplay included. Consistently good gameplay mechanics, that all revolve around making the player understand what it is to be Batman, joined with exceptional artistic direction produce a game that while limited in scope, is compelling for its entire length.
A typical approach to a batman game produces a nondescript product with a compulsory driving section so that we include the batmobile, maybe a flying session to include the batwing and combat based around a batarang that might as well be a reskinned pistol. Rocksteady's genius in making Arkham asylum is that while many of Batman's gadgets are included, they've based the feel and gameplay mechanics around his character not his trappings. Indeed this is a Batman game with no batmobile driving section at all.
Throughout the game the player is made to understand that while batman may be a mere human he's a superhero due to his unstoppable willpower, unshakable moral centre and ability to figure out the weakspots in his enemy's moves. This is acheived not merely by telling the player this about the main character, but by showing it through the way the game plays and the art choices back this up. By doing this, Arkham Asylum provides a narrative experience unique to games.
To give you a few examples of how the gameplay relfects bats' foibles, in combat the player can see when he's about to be hit by an indicator temporarily above an enemy's head, while very 'gamey' this gives the player a little bit of Batman's awareness of his stiuation. His willpower is shown to particularly good effect in 3 scarecrow levels that show Batman refusing to surrender even when his perceptions of his environment are completely altered. Backing this up is amazingly well judged animation that consistently shows a strong purposeful bent to Bats' actions.
All in all, this is game that shows by focusing on expressing a character through all the tools at a game designers disposal, you can produce a game that is interesting, even if like me, you were not a fan of the character beforehand. Truly an exceptional piece of work.