In this day and age, it's hard to come up with something truly original and unique. Everything has already been done. I think the best way of getting something with a unique feel, is to take aspects from different games, and use them in combinations that have never been before. So in this thread, I want you to take aspects from your favorite games, and combine them to make your ultimate game experience.
As for me, I wouldmake a Grand Theft Auto type open world, along with Rockstars brand of gunplay, in Fallout 3's post apocalyptic wasteland and level progression. With a Mass Effect like dialogue tree that comes with game affecting consequences. What type of game would you create?