what about and unground place, themed like doodle dug. (maybe you could meet dug)
It'll have lots of gems everywhere The creatures would be gobblers, snakes, and ghosts. Maybe even skeletons,and spiders.
The npc would be mole people, marleybonians, and tunnling wizards
Maybe there could be really dark places where your character uses a magic lantern to help see. There could be lots of clothes and gear to go with this too.