Interesting idea - we've been trying a sort of decentralised PBM in the Throne Room with the "Will of the Senate" game. Each general fights their own battles, although the economy and army movement etc are determined by the Consul (with directions from the Senate). I've been wondering what would be a suitable PBM with a more "provincial" feel and Greece is the natural.

Working out the logistics of how to do this is non-trivial (passing a savegame around each city player each turn would slow things to a crawl), but not insurmountable.