Red Orchestra: Ostfront 41-45 is a realistic FPS set in the rarely-seen Eastern front of WWII, which had the Allied Russians fighting against the Nazi Germany. A big deal about his game is that it is veeeeery close to the real thing. You have to adjust your aiming for gravity, shootings occur at realistic distances, with similar accuracy, and there are massive vehicular battles involving a few dozen Tanks and Transports. It's not easy in any sense of the word, but once you've figured it out, it's incredibly fun.
http://en.wikipedia.org/wiki/Red_Orchestra:_Ostfront_41-45
The game has a thriving community that have created mods that add all sorts of things, including maps, armies (I know of mods that add US, British, Italian, and Romanian Troops), vehicles, AT cannons (Which were mysteriously absent in the retail game), paratrooping, and even classes (I still don't know why there wasn't a medic class in the basic game when you could die in 2 hits) Again, the game is hard, but there's a lot to do in here. I remember playing as an Artillery commander. You'd have to mark a spot with binoculars, then speak into a radio. About a minute later, the explosions would start. All the effort just makes it even more satisfying to see a tank crumble apart under the explosive rain.
http://en.wikipedia.org/wiki/Red_Orchestra:_Ostfront_41-45
The game has a thriving community that have created mods that add all sorts of things, including maps, armies (I know of mods that add US, British, Italian, and Romanian Troops), vehicles, AT cannons (Which were mysteriously absent in the retail game), paratrooping, and even classes (I still don't know why there wasn't a medic class in the basic game when you could die in 2 hits) Again, the game is hard, but there's a lot to do in here. I remember playing as an Artillery commander. You'd have to mark a spot with binoculars, then speak into a radio. About a minute later, the explosions would start. All the effort just makes it even more satisfying to see a tank crumble apart under the explosive rain.