Arduin (The Arduin Grimoire) was an early "D&D variant" (aka it was extra material for D&D that claimed to be an entirely separate game) created by Dave Hargrave. It was well known for having dozens of extra races into the game (such as phraints), dozens of extra classes (long before Kits, much less PrCs, and including the wide-famed and deeply flawed Techno), and the wildest appearance tables on record (utterly independent height and weight tables, hair and eye could end up with such colours as purple, crystal, and multi-hued -- more based on current punk sensibility than on anime).
I knew a lot of people back in 1976-80 who used the extra spells, bizarre weapons, and totally wild races; I even knew some who played in his game down in the East Bay of California. I knew people who were as fanatical on Arduin (and continued to claim it as an independently created and complete game, despite such typos as "% a Liar" rather than "% in Lair" taken directly over from the original printing of D&D ... leading to the odd situation in Arduin that most dragons would lie like a rug

) as other were on early Traveller.
As a world, Arduin was sorta like Moorcock on acid -- the terrain made no sense, kingdoms base vaguely on a smattering of info about some culture were placed willy-nilly next to each other, and characters of 50th and 60th level were around every corner, as were space aliens and the potential of running across semi-automatic pistols and phaser pistols.
Yep, it was way over-the-top, but then again, that was pretty much all gaming back in the day
