You could do that in the origonal Medieval as well using the console {I forget the commands now} and -ian {debugging} mode . You would start a game , set the A.I. to "fully automatic" and it would chain-resolve turn after turn untill you toggled it off then you could chose whatever faction you wanted {through another console function} including emergent factions . Some of use used this to play the Mongols from their first turn of arrival .
A propper Eras setup would be a good way to allow the game to start in the middle of certain wars and I'd like to see such with full troop numbers deployed from the onset {would make for some interesting starting possitions with some factions} .
Bookmarks