A game that mixes the best aspects of Mirrors Egde + The club + COD4 + Gears of War and throws in a little super natural element in there.
You'd have the guys who run around flying roof top to roof top like a crazy monkey men/ninjas, lightly armed, but fast as hell. Running around like Neo in the Matrix. (mirrors edge/The club).
The Rambo types who come through with Heavy duty weapons made to blow things up, and heavily armored. slow, but they can take as much as they give. Basically a really big, and slow nearly bullet proof Rambo (Gears of War).
The balanced guy who can do a little bit of everything. Quick, but not as mobile as the first guy, but better protected. Not as heavily equipped as the second, but no slouch with the weaponry either. Plays efficiently picking guys off with precision shots (COD4)
3 different views the Call of Duty, the Club, and Gears of War view points. Each class would have it's own set of Weapons that you could unlock as you level up, COD style. Each offering a totally different style of play. Now thats a best selling game and Greatest game of all time contender. Someone make me a game developer already.