How's the challenge format? Something like: [i]Battlefield says: "You are player 1 and have to pick Atlantis against player 2 who is (insert other random name here) and plays Arcoscephale."?
Or do we bid on nations? Do we know opponent's nations before creating the pretender? "as defined" means standard settings (indep 3, standard richness, standard research, common events, graphs on, renaming disallowed)?
I think that's all I can think off I need to know.
