Call of Cthulhu
Officially Call of Cthulhu: Roleplaying Game
Lovecraftian horror tabletop RPG. First published 1981 by Sandy Petersen (Chaosium). Set in 1920s New England (traditional) exploring H.P. Lovecraft's Cthulhu Mythos. Percentile (d100) system + SANITY mechanic where investigators lose mental stability confronting cosmic horror. 7th Edition 2014 current. Longest continuously published RPG after D&D.
What is Call of Cthulhu?
Call of Cthulhu is HORROR TABLETOP RPG based on H.P. LOVECRAFT's CTHULHU MYTHOS. First published 1981 by SANDY PETERSEN + Chaosium (USA). Set traditionally in 1920s NEW ENGLAND but supplements cover PULP ERA 1920s adventure, MODERN, DARK AGES, GASLIGHT VICTORIAN, INVICTUS ancient Rome. Uses PERCENTILE (d100) SYSTEM — roll under target skill %. HALLMARK: SANITY MECHANIC — investigators start with SAN 45-99 (based on Power stat). Encountering horror = SAN loss (small viewing to major encounters can drop 1d20+ SAN). Reaching 0 SAN = permanent insanity/death. Temporary insanity + phobias between. Encourages CAUTIOUS INVESTIGATION over combat — deadly system. INVESTIGATORS typically ANTIQUARIANS, PROFESSORS, JOURNALISTS, PRIVATE DETECTIVES exploring OCCULT MYSTERIES with likely tragic ending. 7TH EDITION (2014) most current — refined mechanics + Pulp Cthulhu variant + Beyond the Mountains of Madness / Masks of Nyarlathotep classic scenarios. LONGEST CONTINUOUSLY PUBLISHED RPG AFTER D&D. Adapted to video games (Call of Cthulhu 2018, Dark Corners of the Earth 2005). Considered ESSENTIAL RPG EXPERIENCE alongside D&D.
Quick facts
Category
Tabletop Role-Playing
Type
Team sport
Players
2–8
Duration
~240 min
Where played
indoor
Field / court
theater of mind + occasional map
Country of origin
🇺🇸 United States
Estimated origin
1st Edition 1981 Sandy Petersen; 6th Ed 2004; 7th Ed 2014 (current); continuous publication since 1981
Olympic
No
Popularity
major
How it works
Objective
Cooperative narrative investigation; discover + confront cosmic horror; survive with sanity + life intact (rarely both).
Rules
Basic rules
d100 vs skill target
Roll 1-100; roll ≤ skill % = success. Under half = hard success; under 5 = extreme; roll 01 = critical.
SANITY mechanic — starts 45-99
Every horror encounter risks SAN loss (0/1d3, 1/1d6, 1d6/1d20 depending horror severity).
Combat highly deadly
Damage rolls quickly kill unprepared investigators. Avoid combat.
Investigator background + occupation determines skills
1920s occupations: Antiquarian, Doctor, Journalist, Cop, Private Eye, Occultist.
Failed SAN checks: temporary insanity + phobias
5+ lost in single check = temp insanity; 20% total SAN loss = indefinite insanity.
Investigators expected to die/go mad
Character mortality high; part of horror atmosphere.
Scoring
Not scored. Character advancement via skill improvement checks. Long-term: survive campaign with sanity intact.
| Action | Points |
|---|---|
| Successful skill use in session | Mark skill for improvement check |
| End of scenario improvement checks | Roll 1d100 > skill for +1d10 improvement |
| Character survives + retains sanity | Achievement in itself |
Win condition · Cooperative narrative — surviving + solving mystery.
Playing area
Called
theater of mind + occasional map
Dimensions
primarily narrative
Mostly narrative theater; occasional battle maps for combat scenes.
Equipment
Keeper Rulebook (7th Ed)
€45; rules + Mythos + scenarios
Investigator Handbook
€30; player character options
d100 dice (2× d10)
Percentile rolls
Classic scenarios: Masks of Nyarlathotep, Beyond the Mountains of Madness
Legendary long campaigns €40-60 each
Investigator sheets + occupation options
Antiquarian, Doctor, Journalist, Occultist, etc.
Strategies
Investigation > combat
Deadly system rewards research + caution over confrontation.
Character bonds + backstory matter
Emotional investment enhances horror; expect character loss.
Keep spare characters ready
Character mortality high; have new sheet ready.
Terminology
- Keeper
- Game Master (equivalent D&D's DM).
- Investigator
- Player character.
- SAN
- Sanity — mental stability stat.
- Mythos
- Cthulhu Mythos — pantheon of cosmic entities.
- Great Old One
- Ancient cosmic entity (Cthulhu, Yog-Sothoth, etc.).
- Cthulhu Mythos skill
- Forbidden knowledge; higher = more insane.
- Hard success
- Roll ≤ half skill; better outcome.
- Push roll
- Retry failed check at higher stakes.
Major competitions
Not competitive — cooperative RPG
n/a · worldwide
Origins + ENnie Awards multiple wins
annual · USA · since 1981
NecronomiCon Providence (annual convention)
biennial · USA · since 2013
Where it is played
Governing bodies
Chaosium Inc. (publisher)
Founded 1975 · USA
Official site ↗
Famous names & records
Famous athletes
- Sandy Petersen (USA, b. 1955) — Original 1981 designer
- H.P. Lovecraft (USA, 1890-1937) — Underlying literary source
- Mike Mason (USA) — 7th Edition co-designer
- Paul Fricker (UK) — 7th Edition co-designer
Learn this sport
beginner
- 1
Buy Starter Set ($25) — includes scenarios + dice + rules
Best entry point.
- 2
Play EDGE OF DARKNESS or DEAD LIGHT — classic short scenarios
1-2 session mysteries.
intermediate
- 1
Keeper Rulebook + full campaign
MASKS OF NYARLATHOTEP considered greatest RPG campaign ever.
- 2
Run your first game as Keeper
Community-shared scenarios online.
advanced
- 1
Custom campaigns + original scenarios
Community publishes scenarios.
Frequently asked
What is Call of Cthulhu?+
HORROR TABLETOP RPG (1981) based on H.P. LOVECRAFT's CTHULHU MYTHOS. Investigators in 1920s NEW ENGLAND explore cosmic horror mysteries — usually with tragic ends. HALLMARK: SANITY MECHANIC (SAN stat 45-99 depleted by horror encounters; reaching 0 = insanity). Uses PERCENTILE d100 system. Longest continuously published RPG after D&D. Extremely influential — invented horror RPG genre. 7th Edition 2014 current. Cult classic; many players consider it best RPG ever alongside D&D.
What is the SAN (Sanity) mechanic?+
SANITY represents mental stability. Start with SAN 45-99 (Power stat × 5). Every HORROR ENCOUNTER triggers SAN CHECK (roll d100 ≤ SAN). Success = lose minimum (0-1); Fail = lose maximum (1d6-1d20 depending on horror severity). Viewing DEAD BODY = 0/1d2; SEEING GHOUL = 0/1d6; SEEING CTHULHU = 1d10/1d100. Reaching 0 SAN = permanent insanity/character retired. Losing 5+ in single check = TEMPORARY INSANITY (round-scale). Losing 20% total = INDEFINITE INSANITY (months of recovery). Considered GENIUS DESIGN — makes cosmic horror mechanically felt.
Is Masks of Nyarlathotep really the greatest RPG campaign?+
MANY CONSIDER YES. Published 1984 (updated 5th Ed 2018), globe-spanning campaign starting NYC → London → Cairo → Kenya → Shanghai → Australia. Investigating a CULT PLOT to summon dark forces during 1925. Legendary among CoC + broader RPG community. Takes 40+ sessions (1 year+ weekly play). Complex npcs, deep mystery, cultural exploration, escalating dread. Frequently voted 'best RPG campaign ever' in polls (Escape Pod Cast surveys, RPG.net community). BEYOND THE MOUNTAINS OF MADNESS (Antarctic) is second-most legendary.
Sources & provenance
- Wikipedia — Call of Cthulhu RPG— Wikipedia
- Chaosium — Call of Cthulhu— Chaosium