Was thinking of something along the lines of the newer Castlevania titles, Lament of Innocence and Curse of Darkness. Both have pretty neat map layouts and puzzles. Could be crypt and ruins tilesets mostly with retextures, although I don't know if you can key specific textures to specific maps or not. You would think so considering the Briny Map for the Leviatan battle doesn't have it's textures or layout appear in any other map. Think this could be a cool mod project not just for TL but for Torchlight 2 as well.