I actually played Arduin with none other than David Hargrave himself. I was an official peon in Chaos Inc, the gaming club at Hargrave's Multiversal Trading Company in Concord CA. I was about 13 or 14 and he would con us kids into cleaning his store for the privilege of hanging out there. It was pretty lame. The game itself was much like the Kits of 2nd Ed, really more like Hackmaster. Everything went further than anything in D&D there were 20th level spells, stats in the twenties,your parentage charts could result in being demon sired or dragon sired with hige bonuses, and my favorite the tenth alignment, Amoral Evil. I am reminded of the scene from Spinal Tap with the amp that went to 11. "Why don't you just make Chaotic Evil, more Evil? Yeah but, Amoral Evil is even more Evil!!!"
He produced a series of "adventures" Citidel of Thunder, Caliban and one other at least. They had some decent background stories, and maps. But the actual dungeons only had ten rooms described or filled with encounters. That way "you could personalize your version of the dungeon." Isn't that great. You pay for a big bound adventure and still have to fill it with encounters and treasure! Hoody Hoo. We didn't know that, so we would wander around these empty dungeons until the DM would say "This room is filled with opalescent hues and ...." sudden there would be flavor text, we'd know it was time for an encounter.
I make fun of it. But it was probably a really well timed game for me. D&D seemed very rule heavy and failry staid compared to Arduin, and my adolescent mind loved all the craziness (you could actually play a Courtesean!). But the Phraints (D&D stole them with the Thri-Kreen) were cool and original. There were other elements that were pretty cool, but mostly it was pretty confusing. There was no attempt at balancing or being consistent (magic items frequently used superlatives that were contradictory, a thing that could cure any disease, a disease that couldn't be cured, etc..) In the one game I played with Mr. Hargrave my character was chased down by a Giant Slug and killed in a spray of acid breath.
I heard David Hargrave died back in the 90's. Whenever I roll a Natural Crit, I raise a glass to him, his critical hit charts were gruesome masterpieces!