Arduin Basic?
The Arduin supplements began as supplements for D&D – OD&D that is. As they grew in popularity, and as TSR cracked down on unauthorized references to its own game within the pages of the Arduin booklets, Hargrave created his own competing RPG – his basic modifications to D&D, codified. The first appearance of this “new RPG” was called “The Arduin Adventure.” It came in a box with some supplemental material and its rule book was also sold separately. The simple, short rules were obviously based on the popular “Basic” D&D book complied by Dr. Holmes.
Geoffrey McKinney has described Hargrave’s production as:
“Imagine Holmes D&D, or B/X D&D, written by a hippy genius while well-supplied with strong red wine, and you’ll have a fair idea of this game.”