This is extremely specific, but I'm looking for an rpg that is playable on social media and has the ability to support an amorphous group of people (strangers playing, people dropping in and out of the game, random people who aren't playing still providing prompts for those who are, etc). Basically, a 1 to N player game. So, not unrelated to prior questions about one-player rpgs, but not quite the same thing.
I'm indifferent as to whether it's a GM-less game or not, as long as it only needs 1 consistent player/GM/etc, though I have trouble imagining a game with a GM that is consistent with these requirements.
Vincent Baker's Sundered Land: A Doomed Pilgrim is quite close to fitting the bill - as it is played by a group over google+ or some equivalent and people can drop in and out - but it still requires a minimum of either two dedicated active players or one plus a large group of desultory contributors. Are there any similar games that could support both group and solo play, or a mixture of the two?