In 1981, Chaosium released Call of Cthulhu, a roleplaying game set in Lovecraft’s fictional world. But the year before that, TSR included a “Cthulhu Mythos” chapter in Deities and Demigods (based on an article in The Dragon magazine from two years prior to that) and Chaosium included an “H.P. Lovecraft Creations” chapter in The Gateway Bestiary for RuneQuest. Since the first publication of Call of Cthulhu, other settings have been created for that system and Lovecraft’s creations have been adapted for many other roleplaying systems. (Note that links on game names lead to RPGGeek).

Call of Cthulhu (Chaosium, 1981)

When it began, Call of Cthulhu was primarily the creation of Sandy Petersen. Since then, it has advanced through several editions, been translated into over half a dozen languages, and won numerous awards. Call of Cthulhu is widely played and is considered one of the best roleplaying games ever created. (Purchase in hardcover from Amazon.com or Barnes & Noble.)

Besides the game’s default 1920s setting, numerous supplements allow play in other eras:

Cthulhu Invictus (Chaosium, 2004)

Set during the height of the Roman Empire, the first century A.D. (Purchase from Amazon.com or Barnes & Noble.)

Cthulhu Dark Ages (Chaosium, 2004)

Translated from the German Cthulhu 1000 AD and obviously set in the 10th century. (Purchase from Amazon.com or Barnes & Noble.)

Cthulhu by Gaslight (Chaosium, 1986)

The setting of Victorian England gives investigators opportunities to encounter Sherlock Holmes, Count Dracula, and Jack the Ripper. (Purchase from Amazon.com or Barnes & Noble.)

1920s and 1930s (Chaosium, 1981)

The default setting for Call of Cthulhu, Lovecraft’s own time.

Achtung! Cthulhu (Modiphius Entertainment, 2013)

The Nazis form a terrifying alliance with Cthulhu Mythos entities during World War II. (Purchase from Amazon.com.)

Atomic-Age Cthulhu (Chaosium, 2013)

Set in the 1950s, investigators must face horrors worse than mere nuclear war. (Purchase from Amazon.com or Barnes & Noble.)

Cthulhu Now (Chaosium, 1987)

Call of Cthulhu brought forward into a more modern and technological setting. (Purchase from Amazon.com or Barnes & Noble.)

Delta Green (Pagan Publishing, 1996)

Also using a modern setting, investigators work for Delta Green, a conspiratorial quasi-government agency. (Purchase from Amazon.com or Barnes & Noble.)

Cthulhu Rising (Chaosium, 2008)

A science-fiction setting in deep space in the year 2271. (Purchase from Amazon.com or Barnes & Noble.)

H.P. Lovecraft’s Dreamlands (Chaosium, 1986)

Lovecraft’s “Dreamlands” tales provide the fantasy setting for this supplement. (Purchase in hardcover from Amazon.com or Barnes & Noble or in paperback from Amazon.com or Barnes & Noble.)

Call of Cthulhu Roleplaying Game (Wizards of the Coast, 2002)

Call of Cthulhu adapted to the d20 System first developed for the third edition of Dungeons & Dragons. (Purchase from Amazon.com or Barnes & Noble.)

Cthulhu Dark (Graham Walmsley, 2010)

Originally published in The Unspeakable Oath issue 19, this is a set of “light” rules for roleplaying in the Cthulhu Mythos. The author’s storytelling guide, Stealing Cthulhu (2011), is based on the notion of “stealing” elements directly from Lovecraft’s stories and then adapting and combining them to create new scenarios.

Cthulhu Live (Chaosium, 1997)

Diceless live-action roleplaying rules for Lovecraftian adventures in the “default” 1920s setting. (Purchase from Amazon.com or Barnes & Noble.)

CthulhuTech (Catalyst Game Labs, 2007)

Rules for playing in a dark future where the human race nears extinction at the hands of invading Mythos horrors. (Purchase from Amazon.com or Barnes & Noble.)

De Profundis (Hogshead Publishing, 2001)

An unusual system that lacks a gamemaster. Players interact through storytelling correspondence, jointly creating their own story as it progresses. (Purchase from Amazon.com.)

Deities & Demigods (TSR, 1980)

The first significant reference to Lovecraft in roleplaying is likely “The Lovecraftian Mythos in Dungeons & Dragons” by Rob Kuntz (and J. Eric Holmes) in The Dragon issue 12 (volume II, number 6, February 1978). It included brief information for Azathoth, Byakhee, Cthuga [sic], Cthulhu, Deep Ones, the Great Race, Hastur the Unspeakable, Ithaqua, the Mi-Go, Nyarlathotep, the Old Ones (Elder Things), Shaggoths [sic], Shub-Niggurath, Yig, Yog-Sothoth, the Elder Sign, and the Necronomicon.
This information served as the basis for the “Cthulhu Mythos” chapter in TSR’s Deities & Demigods, a “cyclopedia” for Advanced Dungeons & Dragons, similar in format to their Monster Manual. The statistics for all the above creatures were greatly expanded for AD&D, Cthuga’s [sic] Flame Creature was added, and Yig was dropped. Because Chaosium had acquired the gaming rights to Lovecraft’s works, TSR opted to remove this chapter from the book’s third printing. More information about this is available in the rec.games.frp.dnd FAQ. (Purchase from Amazon.com.)

Eldritch Skies (Battlefield Press, 2012)

The near-future science-fiction setting is an alternate 21st century in which knowledge of the Cthulhu Mythos is universal. This has provided mankind with the technology to explore hyperspace and brought him face-to-face with the horrors that dwell there. (Purchase from Amazon.com.)

The Gateway Bestiary (Chaosium, 1980)

This collection of “Additional Monsters for RuneQuest” was created by Sandy Petersen. The “H.P. Lovecraft Creations” chapter includes statistics for Deep Ones, the Great Race, the Mi-Go, Nightgaunts, the Old Ones, Shoggoths, and Spawn of Yog-Sothoth. Petersen went on to create the Call of Cthulhu roleplaying game. (Purchase from Amazon.com.)

GURPS Cthulhupunk (Steve Jackson Games, 1995)

This GURPS worldbook combines Lovecraft’s Cthulhu Mythos with the science-fiction settings of GURPS Cyberpunk (1990) and GURPS Cyberworld (1993). (Purchase from Amazon.com or Barnes & Noble.)

The Laundry (Cubicle 7 Entertainment, 2010)

Based on Charles Stross’ “Laundry Files” novels, players work for a branch of the British Secret Service called the Laundry. The game uses Chaosium’s Basic Roleplaying system, the same rules on which Call of Cthulhu is based. (Purchase from Amazon.com or Barnes & Noble.)

Realms of Cthulhu (Reality Blurs, 2009)

Using the Savage Worlds system that focuses on light mechanisms, Realms of Cthulhu provides a feeling more in keeping with its “pulpy” setting. (Purchase from Amazon.com.)

Trail of Cthulhu (Pelgrane Press, 2008)

Set in the 1930s and based on the Gumshoe task resolution system in which players always succeed at investigative tasks, but may receive varying detail. (Purchase from Amazon.com or Barnes & Noble.)

tremulus (Reality Blurs, 2012)

A storytelling game with minimal preparation (“playbooks” provide a framework for character creation) and simple mechanisms (only using two six-sided dice). Both the players and the Keeper carry out “moves” and improvisation plays a key part in the game’s flavor.