I always has a part in my game when I see a civ respawning and want to play with it, with respawns you can get situations that you can't have in a normal game: playing as Iraq, Maghreb or the Mamluks (Islamic Babylonia, Carthage and Egypt) Mexico (Aztecs after occupation) modern China and many others. I suggest having a pop-up message to play as a respawned civ similiar to the "a new civ is being born" it will happen when you only played one civ and a civ will respawn you'll get a "a new civ had declared it's independence, do you want to take control of the INSERT NAME HERE?"