I just finished Arkham Asylum. No spoilers, don't worry.
The thing about the game is that it got me thinking about themed games, and how the gameplay doesn't usually match the theme. For example, Arkham Asylum was a Metroid game.
But it got me thinking. If you were free to make a Batman game, no rules, no regulations, no DC dictating to you, what would you make?
I think the Arkham idea is a good one. You put it in Arkham and not only do you have a limitless supply of supervillains and freaks, you also have a chance to make your game about madness. Every story needs a point or it wallows in itself. Like Arkham Asylum does.
My first move, in making my imaginary Arkham game, would be to ditch the bat. You don't play Batman.
You play the supervillains.
I'm a big fan of replayability and deep, wide gameplay, so I would probably make it an open world (well, open-asylum) game. But there is no centralized leader. You can choose any supervillain, and play through the game in only a loosely scripted manner.
This gives us three points of strong gameplay. One is the specific gameplay of the character - and how their madness affects it. For example, Mr. Freeze and Harley Quinn would play very differently in terms of how they move, attack, and so forth. But more importantly, their psychology affects the way they can interact with the world.
Quinn's silly, childish insanities lend themselves to a kind of Tank Girl feel, tainted by her obsession with the Joker. She would be better able to interact with both supervillains and random inmates, she would play around with pianos or complicated control pads, or so forth. Mr. Freeze would be more likely to disassemble, hack, or repair the devices in Arkham, and to build up a lair. There are a lot of potential ways to do it, and it would require some prototyping to figure it out in detail.
The second point of strong gameplay is the dynamic of all of the supervillains expanding into the asylum. This can not only provide the typical deep gameplay of strategic expansion, but also the added unique flavor of negotiating with total madmen, both from a position of strength and weakness.
The third point of strong gameplay comes from the plot and arcs we can introduce. Using some moderately flexible triggers, we can create an emergent story (we could even re-use the same components in the existing Arkham game, although I don't know why we'd bother). But, more than that, we can also have their madness evolve as the game progresses.
The point of the game is exploring the dynamics of the kind of fantasy madnesses these characters suffer from.
There are many other games you could come up with for a Batman theme exploring a point. It is somewhat hard to find a point that can support a thirty-hour game, but certainly not impossible. You could even make a game exploring the oldies but goodies that Batman has explored in the past, such as the existence of a superhero causing an upward spiral of supervillains.
Perhaps you have some good ideas yourself? At the very least, I hope you understand what I'm trying to say.
If you've played Arkham Asylum, tell me whether you thought the same things about it.