I'm going to suggest something different: A fantasy western!
(Sorry if this whole thing is way too specific, I'm just fantasizing here)
A generation or two ago, a surface nation was driven underground, because of natural disasters, a foreign invasion by gruesome demons, religious/political persecution, or something else that's just too awful for them to easily return, and maybe will come after them at some point. They now live in a vast underground cave complex, in small communities, with a few larger, walled cities.
Light is provided by the precious glow rock, mined and quarried, and prospectors are always searching for more deposits. Both mining companies and individual miners are in operation, and there's bandits and claim jumpers and what have you. There's always need for more glow rock, and it doesn't last forever either.
Food is mostly provided by lizard farms, with herds of lizards transported between farms and towns by handlers or "lizard boys" (somebody can come up with a more elegant term). Lizard rustlers are the worst kind of scum, those guys need to hang!
Everybody favors hand crossbows because reasons! Uhm, like ease of use and all the underground critters are poisonous, so you'd best not let them get close enough to bite you. The military carries great big harpoon guns as well to handle bigger threats.
There's an indigenous people, probably lizard men or "primitive" dark elves. These are seen as barbaric by the newcomers, because they don't have the same level of technology, and can be hostile when their lands and sacred places are invaded. However, they have a rich and spiritual culture.
Yeah, I could probably go on, but you get the picture.