Settings That Would Make for Great Roleplaying

Hey so, what are some settings from fiction that you think might make for solid roleplaying potential but which don't (yet) have an official TTRPG game or supplement? I'd also maybe accept those with obscure or out-of-print supplements.

I was thinking about what sorts of settings make for good or interesting RP potential. For instance, settings with a lot of diverse regions and a state of relative social chaos make for good "classic" roleplaying games, whether science fiction or fantasy. I don't want to limit my imagination solely to those (though I'm interested in hearing some ideas,) so I'm interested in hearing about what settings people on this subreddit might think could make for a solid place to set their games.