For several years I've had this idea for a co-op game bounce around my mind. I've always loved the Mission: Impossible franchise; the movies, the old shows, even some of the crappy games that have been released under its name. What amazes me is that M:I is based on teamwork to pull off objectives, and there's never been a co-op game based around this concept. It could be set up with 4 players, each with their own objectives to complete:
1. The Point Man - This player's objectives would involve fooling guards and targets. You might have to retrieve IMF pickups or acquire data from locked areas. Probably the most difficult character to play, but you get to wear cool disguises Agent 47 style!
2. The Tech Specialist - Your job is to hack computers and electronic devices that may give the Point Man trouble. But first you'd have to get to an access point where you can work. The hacking could be like a puzzle game. You'll need to give the other players feedback as to what's going on that you can see from security cameras as well.
3. The Interceptor/Silencer - You're backing up the Point Man. You might gain access as a guest or a guard. Someone with a much lower profile than who the Point Man is impersonating. You provide on-scene surveillance, and if need be, you may have to silently deal with guards that your Point Man can't get past. Zero body count if possible. Killing anyone will severely lower your whole team's mission rating.
4. The Clutch Guy - You're providing transportation for the team (legal means or otherwise), and you're also ensuring the team can escape. You're generally outside the building or main area of the mission. You may have objectives like cutting the power to the building from the outside or causing a diversion. Your role doesn't quite have as many restrictions as the other members might have, although killing is still a last resort.
Objectives could be dynamic, like if one player fails their task maybe the other players could do something to fix the problem. There would also some sort of suspicion meter a la Hitman. Your team needs to keep low profiles throughout a mission (or high in the Point Man's case as needed.) Also, maybe there could be an optional feature where voice chat could affect the mission, like if the Point Man is talking to the other team members too loudly they might attract unwanted attention.
I think given the right developers, it could be an awesome co-op game, although since it's not some "kill everything that moves" shooter it wouldn't sell like Call of Duty or Battlefield. Communication and working together as a team would be absolutely crucial. What do you guys think?