Call of Cthulhu variants (BRP)
These are CoC games using the Basic Role Playing system (d100). Not all of them are produced by Chaosium.
- Call of Cthulhu the base game, set in the 1920s
- Cthulhu Invictus CoC in the ancient Roman Empire
- Byzance An 800 CoC in IX century Byzanthium (French only)
- Cthulhu Dark Ages CoC in the middle ages (with Averoigne materials in Worlds of Cthulhu)
- Convict & Cthulhu CoC in Australia between 1795 and 1810
- Cthulhu by Gaslight CoC in the XIX century (1890s)
- Achtung! Cthulhu CoC in WWII era (has rules for Savage Worlds as well, and conversions for FATE and Trail of Cthulhu)
- World War Cthulhu CoC in WWII and Cold War eras
- Cthulhu Now CoC in modern times (1990s)
- Delta Green CoC meets X-Files, in the 1990s
- The Laundry CoC meets the MI6, in the 2000s (based on the Laundry book series)
- Dreamlands expansion of CoC dealing with the Dreamlands
- Cathulhu CoC with cat PCs
These are non-BRP games heavily featuring the Cthulhu Mythos. Mostly, these are either conversions of CoC to some other game system, or hybrid games merging the Cthulhu Mythos with another major theme (and often using a rules system suitable for that theme).
- D20 Call of Cthulhu D20 version of CoC
- Trail of Cthulhu GUMSHOE version of CoC, set in the 1930s, or in the Gaslight era
- Realms of Cthulhu Savage Worlds
- Silent Legions Stars Without Number
- Realms of Crawling Chaos Labyrinth Lord
- Eldritch Skies Cinematic Unisystem and Savage Worlds, set in 2030 (sci-fi themed)
- CthulhuTech Framewerk, set in 2085 (mecha-themed)
- Cthonian Stars Traveller, set in the near future
- GURPS Cthulhupunk GURPS, set in the near future (cyberpunk-themed)
- Alba di Cthulhu (a dedicated card based system; the game is set in a post-apocalyptic world after the rise of R'lyeh)
- Clockwork & Cthulhu Clockwork & Chivalry
- Dark Streets OpenQuest / D100 system
These are settings and supplements which include elements of the Cthulhu Mythos into an existing game. The list is definitely not meant to be exhaustive, listing only major supplements/settings.
- Deities & Demigods AD&D book with stats for the Cthulhu Mythos entities (later reprinted as Legends and Lore without the Mythos content).
- Freeport early d20 setting mixing Mythos themes (in particular Yig, Serpent-Men and the Yellow Sign) with a piratical D&D setting (originally for d20, available now for multiple systems including Savage Worlds, AGE, Pathfinder, FATE, True20, Castles & Crusades)
- Strange Aeons is an adventure path for Pathfinder which includes Mythos elements such as the Yellow Sign and the Great Old Ones. References to Cthulhu Mythos are also found in several Pathfinder bestiaries and modules.
- Sandy Petersen's Cthulhu Mythos for Pathfinder is an upcoming bestiary for Pathfinder by Call of Cthulhu's author.
- Primeval Thule is a campaign setting set inspired by the works of R. E. Howard, H. P. Lovecraft and C. A. Smith, which includes Mythos cults and monsters within a Conan-like setting.