To give a vague parallel here, there have been plenty of fantasy worlds that had deserts in them, but it wasn't until Dune came along that somebody explored the idea of an entire world that was a desert and the ramifications thereof. That's the kind of idea I'm thinking of, a particular setting built around a specific environment, and I can't think of any examples in the fantasy fiction I've read or gaming materials I've seen. I've seen one computer game that had a similar premise ... a long time ago. And that's all I can think of.
Problem is, for all my saturation in fantasy gaming, I haven't actually read much fantasy fiction that was written after 1955 or so ... so this could be a complete cliché and I could easily have not heard about it. The fantasy that interests me the most to read is classic pulp sword-and-sorcery, whereas this idea I've got is probably more suited to the contemporary epic.
I'll have to do some research and maybe make some discreet inquiries among my more contemporary-fantasy-minded friends. It could be that this is just the angle I need to really launch a good novel series.