True anonymous "role-playing" multi-player. Hitler can give you orders and get annoyed, maybe even sack you and yet you don't even know who it is in reality.
Ability to implement a true command hierarchy. Players can command at any operational level. No real limit to number of players that can be involved.
True Fog of War, where you really don't know WTF is going on
Much more too, I'm just going off the top of my head.