If you're looking for a system that works perfectly for a play-by-post game, Ironsworn is it. It's the perfect mix of a stroytelling system but with streamlined dice mechanics for conflict resolution. Combat doesn't take a half-hour of dice rolling and checking charts, which amounts to days worth of posts in a message board setting. Ironsworn is elegant and expansive and so easy to import adventures from other systems that I don't think I'll need any other rules set for a long time, if ever. As a solo playing newbie, I've had no issues running Ironsworn for myself thanks to the GM emulation built into the system. It has quickly become my favorite game to play.
As an added bonus, it's quarantine compatible for all viruses and apocalypses.