District 9, I was thinking of a really intellectual game, where you get to explore the storyline though different characters like in Heavy rain. You will need to do a lot of negotiation, yet it will have action as well. Do to the fact that you will need to do a lot of talking, it might be possible for a good player to avoid conflicts. Also it will have a good and evil system (A GOOD ONE) where doing bad things gives you benefits such as the ability to avoid combat, while doing good gives you rather more conflict or nothing.
For instance you are in a fight, some guy who is on your side broke his leg. He is useless, yet he has a quite a powerful weapon that will make combat way more easy. The guy won't give you, so the only way to get the weapon is to kill him, that is bad karma. Also 18+ different endings Etc. The irony here is that the "Bad" thing to is always the easy way. Being the bad guy is easy and you will end up as a human hero, or an alien revolutionist, controlling the city and killing every human in your way. Or die ether ways as a good guy...
Since I started pissing on the good side, I was thinking of that Rev rant episode http://www.youtube.com/watch?v=uXXHGno1vAA . If you play as a bad guy you get 3 more hours of game play. Also, you have only one save file, you have to take consequences.
Combine it with Bioshock styled game play and you got a heck of a blockbuster...