Grimoire Games was a publishing company run by Jim Mathis. Active from 1978 to mid 1981, Grimoire Games's primary focus was the early Arduin series of RPG supplements, written by one of the grandfathers of the genre, David A. Hargrave. The most famous of these Hargrave supplements is the so-called "Arduin Trilogy".
- The Arduin Grimoire (Arduin Grimoire Vol. I). At least two different editions of this volume exist. These editions differ via cover artwork and some internal artwork (p. 79, among others). 1978.
- Welcome to Skull Tower (Arduin Grimoire Vol. II). 1978.
- The Runes of Doom (Arduin Grimoire Vol. III). 1978.
- The Arduin Trilogy is a box set containing the first three Arduin volumes.
- The Arduin Adventure, 1980. Arduin introductory boxed set. Contained the Arduin Adventure book (which was also available separately), a few sheets of magic items, three character sheets, and two 20-sided die.
- Monsters from Arduin (24 monster cards)
- Magic Weapons from Arduin (24 weapon cards)
- Magic Artifacts from Arduin (24 artifact cards)
- Arduin Character Sheets Combined Pack: A set of 24 character sheets for different Arduin races/character classes.
- Arduin Dungeon No. 1: Caliban (mid level adventure)
- Arduin Dungeon No. 2: The Howling Tower (low-level adventure)
- Arduin Dungeon No. 3: The Citadel of Thunder
- Arduin Dungeon No. 4: Death Heart (high-level wilderness and dungeon adventures)
Items distributed by Grimoire Games
- Manual of Aurania
- Wizard's Aide