For Feudalism 3 - make unique, named leaders that you can kill in battle(once dead, always). Roaming armies that are on the map, that can attack your cities(leader of them can attack), start with small country maybe, and allow the countries that you control to rebel after you conquer, with leaders leading rebellions, so game continues indefinately. :) +1 so he sees.
Well, it seems you are better than me!