Page "Basic Role-Playing" Paragraph 7

BRP was conceived of as a genre-generic engine around which any sort of RPG could be played, much like GURPS and the d20 system have become today.

In order to underscore this, Chaosium produced the Worlds of Wonder supplement, which contained the generic rules and several specific applications of those rules to given genres.

Superworld, specifically, began as a portion of the Worlds of Wonder product.