Are you sure they're called FFA? FFA I thought was a 1vs1vs1vs1 teams locked. Diplomacy is teams unlocked.
I've seen FFA's before but not diplomacy.
Yeah I think you are right, it's the length of the game. So with diplomacy though, you can win with an Ally correct? It doesn't have to end in a 1v1... or am I wrong? I liked playing the diplo games in Rise of Nations. Really made for a dynamic experience. Some people might stab you in the back while others would stick with you no matter what. Plus you don't really know who your ally will be until you're in the game part way through. I also wonder how trading pacts would work with humans. When I play SP I like to start a lot of cease fires and trade agreements to boost my economy.