A mix of satire and absurd comedy, the Discworld is literally that: a round, flat disc carried by four enormous elephants, themselves in turn riding on the back of a turtle. Chronicled in the novels of Terry Pratchett, the Discworld began as a satire of the fantasy genre and since metamorphosed into a fantasy-flavored funhouse mirror of the modern world.
This is the setting of the Discworld Roleplaying Game, published by Steve Jackson Games, which is scheduled for release in November of 2016. It is a stand-alone RPG that is compatible with the GURPS Fourth Edition rules. There is also an earlier, out-of-print version of the game which is compatible with GURPS Third Edition.