The Discworld is a flat world that floats through space on the backs of four
giant elephants, which in turn stand on the back of a giant space turtle
(astrochelonia gigantis or something like that, if you speak Old).
Believe it or not, this is actually a very interesting series of books, and
as with many succesful stories a roleplaying game was written for it. So of
course I had to join in some time. As it was play-by-e-mail I don't know a
thing about the system but the setting just has to be hilarious.
Discworld and all associated books are copyright by Terry Pratchett.