Norton I
Warlord
I've given this some thought and I think that the relevant things of vassalship can be used in a game with human players without the vassal option on. Basically, being a vassal state just means that you are protected by a more powerful state and in return you do what they say. In a democracy game, teams can work such agreements out in much detail and don't need a standard game mechanic for it. I'd say turn it off to avoid exploits and encourage teams to come up with their own diplomatic structures.