I had to admit, I was disappointed that Dungeon World was not literally about a World of Dungeons, and it led me to making a setting I haven't used yet, the "Demiplane of Dungeon" (the notes live mostly in my head rather than in any written form, sadly). A living, slowly-shifting dungeon home to numerous sentient beings who are just doing their best to get by in a world that doesn't have a lot of natural food resources, while at the same time not falling to the "full of evil raiders"/"every man for himself" motifs you get in a lot of similar (often post-apocalypse) resource-poor settings.