[1] Hargrave was one of several early RPG players from the San Francisco Bay area to also become a game designer, having started by creating variant rules for his weekly Dungeons & Dragons campaign.

The setting of Arduin was heavily house-ruled and included hundreds of players and was situated in a neutral ground between nations that were once at war with each other.

[2]: 318  Chaosium listed the resulting book on its publication schedule for February 1977 to be its first role-playing game product, but the company instead rejected the incomplete manuscript that Hargrave submitted.

Active from 1978 to mid 1981, Grimoire Games's primary focus was the early Arduin series of RPG supplements, written by Hargrave.

[11] In the April–May 1979 edition of White Dwarf magazine (Issue 12), Don Turnbull gave the just-published Trilogy a below average rating of only 4 out of 10, finding it disorganized, hard to read, and "a mass of information, no doubt useless to some and useful to others."

Turnbull concluded "I could not advise anyone to buy The Grimoire from which to learn the fantasy game hobby from scratch, but if you want what is in effect a D&D supplement, don't mind the price and are prepared to be selective in what you extract from it, there will no doubt be useful snippets you could find.

"[1] In the Oct-Nov 1979 edition of Different Worlds (Issue 5), Mike Gunderloy admired the huge amount of supplementary information in the Arduin Trilogy that could be added to a D&D campaign.

"[13] In his 2023 book Monsters, Aliens, and Holes in the Ground, RPG historian Stu Horvath noted, "with the Arduin zines, Hargrave plants the first seeds of transgression in RPGs.

The zines seem calculated to shock, in the same way that some lurid heavy metal album covers sought to fluster squares with cartoon skulls, demons, and blood.

Second, a Prismatic Wall spell in Arduin appeared to be plagiarized directly from D&D; Hargrave changed some of the description, including some colors.

Hargrave further distanced himself from controversy by using white-out and typing correction tape to mask all direct references to Dungeons and Dragons, and then the volumes were reprinted exactly that way.

[16] Much criticism was made of Hargrave's combat mechanics, to the point where many Game Masters simply used either their own versions, or those of TSR.