personally...I think there's plenty of themes that haven't been put to good use
here are a few examples
1960's spy themes
1970's cop theme
1950's film noir
fantasy first person shooters
1970's soul movie (ie foxy brown...shaft..etc...)
world war 1
cold war espionage...
and what about tron 2.0...? that seemed like it got reviewed well...i never got around to playing the full game though...
FEAR looks promising as well...
what about postal 2...haha while the gameplay was truly horrible it had a "unique" spin on things... imagine if they had actually made a good game to go along with the shocking elements of the game