I just finished Batman:
Arkham City last night, and after completing it, I can easily say that it
is one of the most enjoyable experiences that one can have on a platform. But throughout my playthrough, I
continually wondered what it is that Arkham
City does right that superhero games up to this point haven’t been able to
do. True, there have been a few
good superhero games (the Spiderman games of the PS2
era come to mind), but for the most part, games that are tied
to superheroes have been uninteresting.
After finishing the game, I started to realize what makes the Batman
games (especially the ones made by Rocksteady) so intriguing. 
Na Na Na Batman
One of these realizations was the fact that Batman is
essentially just a smart guy who happens to have cool gadgets and a way
to self fund new ventures. Because
his powers come from his tools and intellect, Batman lends himself very well to
a progression based game, such as Zelda,
where he can get another weapon in his arsenal at a set period that opens up
much more of the world. Yet even
when he does have something like the line launcher, he still feels powerful
enough to where he is fun to play as.
Also, because he is a regular guy, the dynamics of the game can be much
different. Throughout Arkham City (and even in Arkham Asylum), the bosses are tough to
beat, but the much more difficult battles are when you find yourself fighting a
group of 12 different guys. Unlike
someone like Superman, Batman can fairly easily go down to a group of 12 guys
if you do not keep your guards and counters up. Rocksteady realized this was the case,
developed accordingly, and made an exciting experience from it. 
Remember this little gem?
Another thing that Batman has that sets him apart is a very fleshed out universe. Sure, a Green Arrow game could be interesting, but would that many people really want to play it? Batman has integrated himself into popular culture to that point that even people who don’t know much about comics know who The Joker is, while if the same group were polled about Brick (from the Green Arrow series), they would have no idea or any inclination to know who he is. With Batman’s popularity and integration into media, it makes it so that not only fans of the comic or movies will buy the game, but also anyone else who enjoyed any other form of media that includes Batman. While Superman or Spiderman may have the next closest fan bases and large universes, it would be hard to justify a game because what is the incentive to progress? With Batman, there are many new weapons and gadgets to get, in addition to increases in suit and gadget functionality, but it’s not as easy to just remove all of Superman’s powers and have him gain them back eventually without making the story seem ridiculous. And with Spiderman, the scope is slowly starting to shift away from the thing that made Spiderman games fun in the beginning, which was the ability to swing around a large city without much consequence. I certainly think that Rocksteady could make a good Spiderman game, but until that time, the Batman will rule over superhero game superiority.