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Call of Cthulhu marks the horror RPG’s 40th anniversary with a new Keeper Rulebook

Limited-edition tome includes designer commentary and return of classic scenario.

Horror roleplaying game Call of Cthulhu is marking 40 years since its release with a limited-edition revision of the RPG’s Keeper Rulebook.

Call of Cthulhu was released in 1981 by Chaosium, the publisher that built its game of Lovecraftian monsters, cults and mystery on the Basic Roleplaying gameplay system previously used in RuneQuest. Like the earlier fantasy RPG, Call of Cthulhu used percentile rolls - calculated with d100, or two ten-sided dice - to resolve tests, with players’ characters improving their skills as they used them.

The RPG’s horror theme, rooted in the Cthulhu mythos, and punishing gameplay - which saw players’ human characters become infamously fragile academics and investigators, unlike the heroic adventurers of D&D - helped it gain a cult following that spawned seven editions of the core RPG and a number of spin-offs. Among the more notable descendants of Call of Cthulhu is board game Arkham Horror, which later grew into the separate Arkham Horror Files franchise, and standalone tabletop RPGs such as Trail of Cthulhu and Delta Green that began as licensed spin-offs.

The 40th Anniversary Keeper Rulebook - Call of Cthulhu’s equivalent to the Dungeon Master’s Guide, named for the Keeper that runs each game - will feature the game’s core rules alongside a variety of extra content marking the occasion. The limited-edition rulebook will also see a visual revamp, with a leatherette cover and dust jacket, plus new endpapers inside its covers.

Among the additions will be commentary and recollections from designers, writers and contributors from Call of Cthulhu’s early days. The tome will also reintroduce The Haunting, a scenario previously included in the first six editions of Call of Cthulhu, before being removed for its latest seventh edition core rulebook, released in 2014. (The scenario was included in Seventh Edition’s quickstart rules.)

Chaosium said that the 40th Anniversary Keeper Rulebook would be limited in availability, with a pre-launch at Gen Con this week before an official release next month. A price is yet to be announced.

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About the Author
Matt Jarvis avatar

Matt Jarvis


After starting his career writing about music, films and video games for various places, Matt spent many years as a technology, PC and video game journalist before writing about tabletop games as the editor of Tabletop Gaming magazine. He joined Dicebreaker as editor-in-chief in 2019, and has been trying to convince the rest of the team to play Diplomacy since.

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