The Fimir were created at the behest of Games Workshop's then-owner, Bryan Ansell who wanted a race "to be as distinctive of Warhammer as the Broo are of Runequest".
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.