While I am not particularly fond of Monte Cook's more recent works (that is, the #Cypher system and the settings that were published for it), his Ptolus city book is one of my all-time favorite #ttrpg settings.

I love the kind of exhaustive detail and lore you only get when a setting has been developed for years. And the setting has enough internal consistency to justify most of the usual "Dungeon Fantasy" tropes - including explanation for just why there are all these dungeons to explore and baddies to fight for player character types.

One day, I want to run a campaign set in it. I'm not sure which system I'd use - #GURPS would be my favorite, with #Pathfinder2e being the close second. But I'm sure I would enjoy it.