Call of Cthulhu RPG (1988–2016)
- S. Petersen's Field Guide to Cthulhu Monsters (1988)
- S. Petersen's Field Guide to Creatures of the Dreamlands (1989)
- The Great Old Ones (1989)
- Delta Green (1997)
- Escape from Innsmouth (1997)
- H.P. Lovecraft's Dunwich (2002)
- The Keeper's Companion 2 (2002)
- H.P. Lovecraft's Arkham (2003)
- H.P. Lovecraft's Kingsport (2003)
- The Keeper's Companion Vol. 1 (2003)
- Shadows of Yog-Sothoth (2004)
- Miskatonic University (2005)
- Spawn of Azathoth (2005)
- The 1920s Investigator's Companion (2005)
- Malleus Monstrorum (2006)
- Tatters of the King (2006)
- Mansions of Madness (2007)
- Cthulhu Invictus (2009)
- Call of Cthulhu Keeper's Screen (2011)
- Atomic-Age Cthulhu (2015)
- Doors to Darkness (2016)
- S. Petersen's Field Guide to Lovecraftian Horrors (2016)