I'm honestly a complete noob to tabletop RPGs, having only read the manuals for DnD 4th edition and never having played, but I'd like to know if an RPG or setting for one exists for China Miéville's book Un Lun Dun. It's a personal favorite, and I think it would make for some great gameplay. If not, how would one go about creating a setting and in which RPG, and how difficult would this be?