Especially in 64-player games, a lot of people end up quitting. I think that there should be a mechanism to replace quit or AFK players with new players who volunteer to do so.
Sound like something Premium players should be able to do.
There could be a menu for premium players of games they can join, replacing players who have quit or have been removed for inactivity, where the player still has stars.
Could be an option when creating a new game “Allow New Players to Replace AI’s”.
The players in the game should be notified when an AI is replaced, in the same way they are told about an player quitting of being removed for inactivity.
I’m not sure about the value joining a game in the late stages, maybe only allow joining if no player has reached 50% of the victory condition yet.
Also not sure a player should be allowed to rejoin the game in this way (there is an admin option which reinstates a inactive player already).