What Is Call of Cthulhu and How Do You Start Playing?

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Call of Cthulhu is a horror-investigation tabletop roleplaying game published by Chaosium, in which players take on the roles of ordinary investigators uncovering cosmic horrors inspired by H.P. Lovecraft's mythos. To start playing, pick up a Starter Set if you're new to the game, gather a group of players, and run one of the included scenarios. If you already know you want the full rules, go straight to the Core Rulebooks.

What Makes Call of Cthulhu Different From Other TTRPGs

Most fantasy RPGs cast you as powerful heroes who grow stronger by defeating monsters. Call of Cthulhu inverts that: your investigators are ordinary people — journalists, professors, detectives — who are fragile, and the more you learn about the mythos, the more your sanity erodes. The game is about survival and discovery, not power fantasy.

The Core Play Loop

Play follows a repeating cycle:

  1. An investigation begins. The group receives a hook — a missing person, a strange death, an old letter — and starts asking questions.
  2. You gather clues. Investigators search locations, interview witnesses, and read documents. Skills like Library Use, Spot Hidden, and Psychology drive this phase.
  3. You confront the unknown. Eventually the clues point to something unnatural. Combat is dangerous and often a last resort; running away is frequently the smart move.
  4. Sanity is tested. Encountering mythos entities or forbidden knowledge costs Sanity points. Losing too much leads to temporary or lasting madness — a core mechanic that distinguishes the game from heroic fantasy systems.

The tension between "I need to know what's happening" and "knowing will destroy me" is the engine of the game.

Choosing Your Entry Point: Starter Sets vs. Core Rulebooks vs. Slipcase Sets

Chaosium's own site organizes its Call of Cthulhu lineup into three tiers, and the right choice depends on how committed you already are.

Product tier Best for What you get
Starter Sets Complete beginners and groups new to the game A streamlined introduction to the rules plus ready-to-run scenarios, so you can play without buying anything else
Core Rulebooks Players who want the full game The complete rules for creating investigators and running long-term campaigns
Slipcase Sets Committed groups and collectors The core rules bundled with supplementary material in a single package

How to decide:

  • Never played a TTRPG before, or unsure about horror? Start with a Starter Set. It's designed to get a group playing quickly with minimal prep.
  • Experienced GM who wants full character creation and campaign play? Go with the Core Rulebooks.
  • Already know you'll run an ongoing game and want the extras? The Slipcase Sets bundle the core material with supplements, which is more economical than buying each piece separately.

Chaosium is the official publisher and the authoritative source for the game, so buying directly from them or a retailer carrying their products ensures you get current editions. Note that the site lists products with prices (for example, a hardcover companion listed at $47.99), but check the current listing for exact pricing and availability before ordering.

How to Start Playing: Step by Step

  1. Get a Starter Set. This gives you the rules and at least one scenario ready to run. You don't need the Core Rulebooks to begin.
  2. Gather 2–5 players plus a Keeper. One person acts as the Keeper (the game master), who presents the mystery and controls the world. The rest play investigators.
  3. Read the included scenario before the session. The Keeper should know the clues, the key locations, and how the mystery resolves.
  4. Create or pick investigators. Starter Sets typically include pre-generated characters, so you can skip character creation for your first session.
  5. Run the scenario. Play proceeds through investigation, skill rolls, and Sanity checks as described above.
  6. Debrief and decide on next steps. If the group enjoyed it, move to the Core Rulebooks for full character creation and longer campaigns.

Common Sticking Points

  • "My players want to fight everything." Make clear up front that combat in Call of Cthulhu is lethal and often avoidable. Frame the game as investigation first.
  • "Sanity loss feels punishing." That's intentional — it's the genre. Lean into the tension rather than treating it as a failure state.
  • "Which scenario should we run first?" Use whatever scenario comes in your Starter Set; it's chosen to teach the rules. Don't homebrew a mystery for your first session.

Quick Answer Recap

Call of Cthulhu is Chaosium's horror-investigation RPG where ordinary investigators solve mysteries at the cost of their sanity. New players should buy a Starter Set, gather a Keeper and a few players, and run the included scenario. Move to the Core Rulebooks once the group is hooked, and consider Slipcase Sets if you want the full package in one purchase.