I'm up for another game. As someone who appreciate the roleplaying side of OW, having some sort of player-enforced variant sounds fun. A few random ideas, most of them bad:
1) Pacifist run - cities aren't allowed to build anything under the military category
2) Warmonger run - no founding, only conquering! Not allowed to use settlers
3) Celibacy - no marriage allowed! We have to rely on "adopt an heir" events to continue our legacy
4) Barbarian run - no workers allowed! All tiles must remained unimproved