I found myself really digging Die, a comic about a group of adults who had a traumatic experience playing D&D in their teens (more or less getting stuck in the game world, Jumanji-style, for two years) and who then return to the world once again.
Kieron Gillen, the comic author, developed an RPG for the comic that is influenced greatly by PbtA philosophy: http://diecomic.com/rpg/
I wonder if it'd be possible to set up a game that's based on the comic's premise, using the RPG rules.
The biggest downside is that the game suggests each character is unique in their role--but I'm considering having PCs from different groups who've come to the world (and either having other PCs as part of their original party, allowing them to be apped in +roster style, or just letting them be NPCs in a backstory).
Worth considering further? Or is it too difficult to juggle that sort of "different clusters of 'unique' character types" premise?