I'm playing in two: Crabbe in
Galactic Prison Riot (coincidentally along with PK) and Goat Moonbeam in the increasingly not safe for work
Goat Simulator.
I'm not narrating one yet, but am just trying to get my face-to-face group interested.
Quite apart from full stories, one potential use is to run 'between adventures' sessions, as the asynchronous aspect means that your PCs can go off in different directions and at different paces quite happily, ready to be brought back together for the next live session.
Graham