This forum seems to attract a thoughtful bunch, so let me propose an idea I imagine would be great fun in a FPS, RTS, and maybe other genres as well?
You take your players, (humans are ideal, but an AI could work) and divide them into various team. There can be any number of teams, and the teams don't always have to be equal in size. Give each team a random objective, and these objectives should usually force some conflict or competition between the various teams. Give each team information about their objective, but do not always reveal the opposing teams objectives or the complete scenario. Award points based on success (including partial success) of objectives.
Consider a few of the possible scenarios which might occur:
Team 1 is given the objective to defend an object ("the football", I'll call it). Full points are given if the football is kept safe the entire game. Partial points are given if the football is captured, but not destroyed.
Team 2 is given the objective to capture the football. Full points are given if the football is captured. Partial points are given if the football is not destroyed.
Team 1 and team 2 are both aware of each other and are aware they will be in competition over the football - yet neither team is aware of the third team....
Team 3 is given the objective to destroy the football.
So now we have both team 1 and team 2 who are fighting over the football, but neither team is willing to destroy the football (as they can obtain at least partial points so long as the football is not destroyed). Then a surprise third team shows up during the actual game which is attempting to destroy the football. Team 1 and team 2, although competing against each other, might do well to cooperate against team 3.
A simpler example:
Team 1 and team 2 are both large teams with infinite respawns, and they are pitted against each other in a team death match (FPS game). Team 3 is a smaller team with no respawns and must escort a specific player though the chaos.
Another:
Team 1 defends a target team 2 is attacking.
Team 3 defends a target team 4 is attacking.
Team 1 and team 3 are unaware of each other, how will they react?
When the scenarios are finished teams are awarded their score and there is full discloser of all teams and their objectives. About the objective information given before the game: You would have to be completely honest about some things, namely the scoring objectives, people need to know the real objective of the game, even if they don't know the entire situation surrounding the objective. All players would understand in advance that they may not be aware of the entire situation; they may not know about all teams or objectives.
I have played around with some proof of concept code which generates these sceneries and it works. What I'm still trying to balance (and it would depend on the details of the game it was actually implemented in) would be how to balance the scoring based on the difficulty of your task.
Now that I've explained and demonstrated the idea I'll share my source of inspiration: In COD4, in the sniper level, you sneak through an apartment complex which is empty, but it was really tense the first time because you never know whether you might run into someone or not. You get setup and wait for a meeting between two terrorist groups (whatever?), you then have to snipe a specific target during this meeting. I loved the feeling of being alone and hidden during this level, and the tensity of wondering if anyone is in the building with you (the first time at least, the level always plays out the same). Could such a situation ever be created in a multiplayer environment? It could - maybe.
Pit two teams against each other in a tense situation with a 3rd unknown team set to sabotage the situation. Of course, sometimes you'll have to allow the "meeting" to go peacefully (that is, instruct both team 1 and team 2 to not engage each other, and do NOT have a secret 3rd team), but then you end up with a scenario without any action. Some may consider that boring, but you would always be suspecting a conflict, and perhaps this alone would be enough to keep things interesting?
Maybe the online community, especially the FPS crowd, would never go for something so complex. What was suppose to be a tense situation would be running by people jumping up and down on top of cars while others are off in the corner trying to glitch their way out of the map. Maybe the whole thing is too complicated? Would people get frustrated and abandon objectives, turn to team killing or other greifing?
Again, this seems to be a fairly thoughtful group and open to new game ideas, so I'm interested in any comments or questions anyone has. Thanks. (Also, have I posted this on these forums before? I thought I had, but can't find the old post.)