Call of Cthulhu is a horror fiction role-playing game based on H. P. Lovecraft's story of the same name and the associated Cthulhu Mythos. The game, often abbreviated as CoC, is published by Chaosium and was originally created by Sandy Petersen; it was first released in 1981 and is in its seventh edition, with licensed foreign language editions available as well. Its game system is based on Chaosium's Basic Role-Playing (BRP) with additions for the horror genre. These include special rules for sanity and luck. It is one of the longest-running tabletop role-playing games still in publication.

In Call of Cthulhu, players control ordinary people: investigators, typically in the game's default historical 1920s setting, seeking to solve and uncover paranormal mysteries, usually linked to the Cthulhu Mythos, and survive its deadly creatures that are harmful to their lives and the human psyche. At its release in 1981, the game was notable for its emphasis on psychological horror, investigation, and character vulnerability rather than combat and heroic adventures, departing from the conventions of many contemporary role-playing games. Widely regarded as a pioneering horror role-playing game, it influenced numerous later games and helped establish horror as a major tabletop RPG genre.

Call of Cthulhu has also been adapted for video, card and board games using the setting and the Call of Cthulhu brand. Some include Call of Cthulhu: The Card Game, the board game Arkham Horror, and video games Call of Cthulhu: Dark Corners of the Earth and Call of Cthulhu (2018).

Gameplay Setting Call of Cthulhu is set in a darker version of our world based on H. P. Lovecraft's observation (from his essay, "Supernatural Horror in Literature") that "The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown." The original edition, first published in 1981, uses Basic Role-Playing as its basis and is set in the 1920s, the setting of many of Lovecraft's stories. Many supplements expanded the game's setting beyond the original 1920s to different historical periods and otherworldly locales. The Cthulhu by Gaslight supplement blends the occult and Holmesian mystery and is mostly set in England during the 1890s. Cthulhu Now and Delta Green are set in a modern/1980s era and deal with conspiracies. Recent settings include 1000 AD (Cthulhu: Dark Ages), the 23rd century (Cthulhu Rising) and Ancient Rome (Cthulhu Invictus). The protagonists may also travel to places that are not of this earth, such as the Dreamlands (which can be accessed through dreams as well as being physically connected to the earth), Carcosa, other planets, or the voids of space. In keeping with the Lovecraftian theme, the gamemaster is called the Keeper of Arcane Lore ("the keeper"), while player characters are called Investigators of the Unknown ("investigators").

While predominantly focused on Lovecraftian fiction and horror, playing in the Cthulhu Mythos is not required. The system also includes ideas for non-Lovecraft games, such as using folk horror or the settings of other authors and horror movies, or with entirely custom settings and creatures by the gamemaster and/or players.

Mechanics

CoC uses the Basic Role-Playing system first developed for RuneQuest and used in other Chaosium games. It is skill-based, with player characters getting better with their skills by succeeding at using them for as long as they stay functionally healthy and sane. They do not, however, gain hit points and do not become significantly harder to kill. The game does not use levels.

CoC uses percentile dice (with results ranging from 1 to 100) to determine success or failure. Every player statistic is intended to be compatible with the notion that there is a probability of success for a particular action given what the player is capable of doing. For example, an artist may have a 75% chance of being able to draw something (represented by having 75 in Art skill), and thus rolling a number under 75 would yield a success. Rolling or less of the skill level (1–15 in the example) would be a "special success" (or an "impale" for combat skills) and would yield some extra bonus to be determined by the keeper. For example, the artist character might draw especially well or especially fast, or catch some unapparent detail in the drawing.

The players take the roles of ordinary people drawn into the realm of the mysterious: detectives, criminals, scholars, artists, war veterans, etc. Often, happenings begin innocently enough, until more and more of the workings behind the scenes are revealed. As the characters learn more of the true horrors of the world and the irrelevance of humanity, their sanity (represented by "Sanity Points", abbreviated SAN) inevitably withers away. The game includes a mechanism for determining how damaged a character's sanity is at any given point; encountering the horrific beings usually triggers a loss of SAN points. To gain the tools they need to defeat the horrors – mystic knowledge and magic – the characters may end up losing some of their sanity, though other means such as pure firepower or simply outsmarting one's opponents also exist. CoC has a reputation as a game in which it is quite common for a player character to die in gruesome circumstances or end up in a mental institution. Eventual triumph of the players is not guaranteed.

History The original conception of Call of Cthulhu was Dark Worlds, a game commissioned by the publisher Chaosium but never published. Sandy Petersen contacted them regarding writing a supplement for their popular fantasy game RuneQuest set in Lovecraft's Dreamlands. He took over the writing of Call of Cthulhu, and the game was released in 1981. Petersen oversaw the first four editions with only minor changes to the system. Once he left, development was continued by Lynn Willis, who was credited as co-author in the fifth and sixth editions. After the death of Willis, Mike Mason became Call of Cthulhu line editor in 2013, continuing its development with Paul Fricker. Together they made the most significant rules alterations, more so than in any previous edition, culminating in the release of the 7th edition in 2014.

Editions

Edition Published Format Notes 1st edition 1981 Boxed set Includes the 16-page Basic Role-Playing booklet in addition to the main rulebook. 2nd edition 1983 Boxed set Includes a single rulebook; minor rules changes (summarized in 619 words in the Cthulhu Companion). 3rd edition 1986 Boxed set Divided the rules into a separate Investigator's Book and a Keeper's Book booklets. 4th edition 1989 Softcover Includes content from the Cthulhu Companion and Fragments of Fear: The Second Cthulhu Companion supplements. 5th edition 1992 Softcover The first version to credit Lynn Willis as co-author. Edition 5.5 1998 Softcover Reorganized and updated version of the 5th edition, with new cover art; the "Edition 5.5" designator appears on the title page. Edition 5.6 1999 Hardcover Corrected revised printing; the "Edition 5.6" designator appears on the title page. Edition 5.6.1 2001 Hardcover Corrected revised printing; the "Edition 5.6.1" designator appears on the title page. 20th Anniversary Edition 2001 Leather-bound hardcover book Limited edition bound in green leather, with new "ancient tome" layout. 6th edition 2004 Hardcover, softcover, or PDF Same layout and content as the 20th Anniversary Edition. 7th edition 2014 Hardcover, softcover, or PDF The rules were significantly revised by Paul Fricker and Mike Mason. New cover art and a full-color layout. The print version was released in spring 2016.

Early releases For those grounded in the RPG tradition, the very first release of Call of Cthulhu created a brand new framework for table-top gaming. Rather than the traditional format established by Dungeons & Dragons, which often involved the characters wandering through caves or tunnels and fighting different types of monsters, Sandy Petersen introduced the concept of the Onion Skin: Interlocking layers of information and nested clues that lead the player characters from seemingly minor investigations into a missing person to discovering mind-numbingly awful, global conspiracies to destroy the world. Unlike its predecessor games, CoC assumed that most investigators would not survive, alive or sane, and that the only safe way to deal with the vast majority of nasty things described in the rule books was to run away. A well-run CoC campaign should engender a sense of foreboding and inevitable doom in its players. The style and setting of the game, in a relatively modern time period, created an emphasis on real-life settings, character research, and thinking one's way around trouble.

The first book of Call of Cthulhu adventures was Shadows of Yog-Sothoth. In this work, the characters come upon a secret society's foul plot to destroy mankind, and pursue it first near to home and then in a series of exotic locations. This template was to be followed in many subsequent campaigns, including Fungi from Yuggoth (later known as Curse of Cthulhu and Day of the Beast), Spawn of Azathoth, and possibly the most highly acclaimed, Masks of Nyarlathotep.

Shadows of Yog-Sothoth is important not only because it represents the first published addition to the boxed first edition of Call of Cthulhu, but because its format defined a new way of approaching a campaign of linked RPG scenarios involving actual clues for the would-be detectives amongst the players to follow and link in order to uncover the dastardly plots afoot. Its format has been used by every other campaign-length Call of Cthulhu publication. The standard of CoC scenarios was well received by independent reviewers. The Asylum and Other Tales, a series of stand alone articles released in 1983, rated an overall 9/10 in Issue 47 of White Dwarf magazine.

The standard of the included 'clue' material varies from scenario to scenario, but reached its zenith in the original boxed versions of the Masks of Nyarlathotep and Horror on the Orient Express campaigns. Inside these one could find matchbooks and business cards apparently defaced by non-player characters, newspaper cuttings and (in the case of Orient Express) period passports to which players could attach their photographs, increasing the sense of immersion. Indeed, during the period that these supplements were produced, third party campaign publishers strove to emulate the quality of the additional materials, often offering separately-priced 'deluxe' clue packages for their campaigns.

Additional milieux were provided by Chaosium with the release of Dreamlands, a boxed supplement containing additional rules needed for playing within the Lovecraft Dreamlands, a large map and a scenario booklet, and Cthulhu By Gaslight, another boxed set which moved the action from the 1920s to the 1890s.

Cthulhu Now In 1987, Chaosium issued the supplement titled Cthulhu Now, a collection of rules, supplemental source materials and scenarios for playing Call of Cthulhu in the present day. This proved to be a very popular alternative milieu, so much so that much of the supplemental material is now included in the core rule book.

Lovecraft Country Lovecraft Country was a line of supplements for Call of Cthulhu released in 1990. These supplements were overseen by Keith Herber and provided backgrounds and adventures set in Lovecraft's fictional towns of Arkham, Kingsport, Innsmouth, Dunwich, and their environs. The intent was to give investigators a common base, as well as to center the action on well-drawn characters with clear motivations.

Terror Australis

In 1987, Terror Australis: Call of Cthulhu in the Land Down Under was published. In 2018, a revised and updated version of the 1987 game was reissued, with about triple the content and two new games. It requires the Call of Cthulhu Keeper's Rulebook (7th Edition) and is usable with Pulp Cthulhu.