Cloud gaming is effectively impossible due to little things like the speed of light. Sure, you could play Civilization via cloud but good fucking luck with competitive shooters.

Would be cool to play civ5 on a long term server.

I’m thinking something that emails you when its your turn too. Like playing chess over mail.

Civ over mail. Physical mail. Like those old mail chess games in the times before online chess (use lichess.org btw <3 ).

Move a scout, wait 3-5 days for the answer.

The best free, adless Chess server

Free online chess server. Play chess in a clean interface. No registration, no ads, no plugin required. Play chess with the computer, friends or random opponents.

lichess.org
Interesting. I mean it more in the sense that civ is just a long game regardless, so some async maybe help.