Anything, that you are playing against the winning team would be controversial. I think you could do a World War 2 game where you play as the Russians.
Actually, I would love a Civil War game, but that will never happen because it is Americans killing Americans...but also War was very different back then. People fought by marching in a line and firing...that is not an interesting Video Game.
Now, they could take a game and put it in the past, but design levels and such around more modern warfare...but then it isn't historically accurate.