Crusader Kings II has a whopping 32 player online multiplayer mode. Something not often found in games of this sort which can make for a very intense and strategic gameplay session.

The game allows for one to make their own choices with there being many "win" conditions in that you can choose to progress how you like. Want to take over all of Europe, that is possible, want to create a successful lineage of family that keeps to themselves, this is also possible.