Something very weird has happened in the game. I don't think this is intended behavior, but maybe I'm wrong.
I can't post a screenshot because of obvious competitive reasons, but anyone that has met AstralPhaser Empire (the one whisperr was handling until 2 turns ago) can check what I've seen.
Its values on the graphs have dropped tremendously. At first I thought the AI was rearraging efforts, like removing from Tech and making gold and troops (AI loves to do that), but then I saw that in nearly all graphs it had a tremendous drop, even those like Espionage (that I've never seen a drop, only horizontal segments as the worst case).
I thought the civ had died, but then I can see some strong and scary horsemen roaming near my borders.
So what exactly this retire option does? I can see the civ's units with their flag and allegiance, and also the nation in the player list, but those demographic changes are too drastic to be conceivable to me.