I think that a setting that could be interesting to both the masses and us would be something set in current times, but with a twist of conspiracy (not bush did 9/11). A more smaller-scaled type of scenario, put in an exotic locale to make things more interesting. An Iraqi insurgent group planning to take control of an important base (or whatever), with the quests given to you by the cell leader - acquiring weapons, ambushing convoys, stealing plans ... eventually you find out that the cell leader used you all to capture a nuclear rocket silo (or maybe just a briefcase of plutonium) and plans to fake a US attack on Iraq with the use of WMD to spark ultimate repricussions for the US... now you get to choose whether you allow him to do that and kill millions of your countrymen, or if you save them, or maybe use the WMD on another country... that would be pretty sweet. It would be something you could relate, with the potential for plot twists, and you can easily expand on the story: there can be relationships (no I don't mean romance) with the other cell members, suspicion thrown around, maybe a US Army soldier with whom you develop a sort of "nemesis" relationship i.e. he tries to stop all your missions, you somewhat find respect for each other or quite the opposite depending on your own choices and the way you go through missions.