1. New Gadgets
2. Every Playable Character Possible
4. Lots of Costumes
5. Finish the unsolved Mysteries
In Arkham City there are a couple side missions that end on a cliffhanger...well...one cliffhanger and a prophecy. So now that we are on the final Rocksteady game I and probably a large amount of fans want some closure on these missions.
Well, that's the end of my list...turns out these games are so well made that my list of things I wanna see is short. I have no doubt the game will be fun, well written, well acted, a time killer, and a compelling mystery. So as long as Rocksteady doesn't get lazy and release the same game they already made (though given the stuff we know about the game already this isn't happening), we are all in store for the greatest superhero game ever made. The only downside of this game is that nobody is going to follow their example and create a say, Avengers/Justice League Game that plays as well.