While at Chaosium he also created Stormbringer, Worlds of Wonder, Elfquest, and Superworld, and contributed to Thieves' World and Call of Cthulhu.
Written by Basic Role-Playing and RuneQuest author Steve Perrin, Superworld began as one third of the Worlds of Wonder product, which also included a generic fantasy setting, "Magic World", and a generic science fiction setting, "Future World", all using the same core Basic Role-Playing rules.