 Henderson's work includes "RuneQuest", "Worlds of Wonder" and "Superworld", and a partner in DunDraCon.He was one of the founders of the Society for Creative Anachronism (SCA), where he was known as Sir Steven MacEanruig.He wrote the first "RuneQuest" adventure supplement, "Balastor's Barracks" with assistance from Steve Perrin and Warren James.