How to play Call of Cthulhu

How to play

Character creation: Your investigator has eight characteristics: Strength, Constitution, Size, Dexterity, Appearance, Intelligence, Power and Education, each a percentage. Roll them, or for a quick start assign 80, 70, 60, 60, 50, 50, 50 and 40 as you like. Hit Points are (CON + SIZ) ÷ 10, Magic Points are a fifth of POW, Sanity starts equal to POW, and Luck is 3D6 × 5. Choose an occupation, such as Professor, Journalist or Occultist, then raise its skills and a few personal interests. Nobody starts with any Cthulhu Mythos skill.

The percentile system: Roll the tens and units dice together for a result from 01 to 100, and succeed if you roll at or under your skill or characteristic. At or under half is a Hard success and at or under a fifth is Extreme; the Keeper says when a task needs one. A bonus die adds a second tens die and you keep the better; a penalty die keeps the worse, and one of each cancels out. If you fail, you can push the roll by describing a greater effort and rolling again, but if the push fails the Keeper inflicts something worse. Combat rolls can't be pushed. Mark each skill you use successfully: at the end of the scenario it may improve.

Sanity: Meeting the horrors of the Mythos, or something mundane but horrific, calls for a Sanity roll against your current Sanity. Losses read like 1/1D6: lose 1 if you succeed, 1D6 if you fail. Lose 5 or more from one roll and you make an INT roll; if it succeeds, you understand what you saw and go temporarily insane for 1D10 hours, starting with a bout of madness. Losing a fifth of your current Sanity in one day brings indefinite insanity, and at 0 you are permanently insane. Your Cthulhu Mythos skill grows as you learn the truth, and your maximum Sanity is 99 minus that skill.

Investigation structure: A scenario opens with a hook, such as a landlord asking you to look into a house. You follow leads through research (Library Use), searching (Spot Hidden, Listen) and people (Charm, Fast Talk, Intimidate, Persuade), receiving handouts as you go, until you understand the threat well enough to face it.

Combat: Everyone acts in DEX order, highest first; a readied firearm acts at DEX + 50. When attacked in melee you choose to dodge or fight back, both sides roll, and the better level of success wins. You can't dodge a bullet, but you can dive for cover. Taking half your Hit Points or more in one blow is a major wound: make a CON roll or fall unconscious. At 0 Hit Points with a major wound you are dying.

Strategy

Call of Cthulhu rewards investigators who treat each scenario as a mystery to solve rather than an action adventure. Investigation is the core of play: Library Use, Spot Hidden and Listen find most clues, and the social skills (Charm, Fast Talk, Intimidate, Persuade) open doors. Make sure the group covers them between you, and read every handout closely: the answer is often in the paperwork. Guard your Sanity: It is your scarcest resource and it comes back slowly, through rest and treatment or the reward for completing an investigation. Avoid needless exposure. Mythos tomes are the classic trap: reading one raises your Cthulhu Mythos skill, costs Sanity and lowers the most Sanity you can ever have again. Read what you must, not everything you find. Push with your eyes open: Pushing a failed roll is often worth it when there is no other way forward, but before you roll, the Keeper can hint at what failure will cost. Take that seriously. You can't push combat rolls, so plan fights before they start. Spread the skills: Groups do best when each investigator is strong in different things, such as a researcher, a talker, a searcher and someone who can handle a gun if it comes to that. Two investigators with the same skill set waste a slot. For a group Luck roll, the investigator with the lowest Luck rolls for everyone, so keep an eye on who that is. The Keeper's contract: Good scenarios offer more than one route to each vital clue, so a single failed roll doesn't dead-end the story. If you feel stuck, say so and try another approach rather than repeating the same roll. Know when to run: Combat is fast and lethal. A handgun deals 1D10, and once you have dodged or fought back in a round, every further melee attack on you that round gets a bonus die. Many Mythos creatures shrug off bullets entirely. Investigators who gather enough information and find the unconventional answer (seal the gate, burn the book, expose the cult) survive; those who try to shoot the unkillable do not.

Tips

- Make sure someone in the group has strong Library Use and someone has strong Spot Hidden; between them they find most clues. - Read handouts carefully and keep them together; the answer is often in the paperwork. - Think twice before reading a Mythos tome: it teaches Cthulhu Mythos, costs Sanity and lowers your maximum Sanity for good. - Before you push a roll, ask what failure could cost; you can't push combat rolls. - Levels of success matter: in opposed rolls and melee, a Hard success beats a Regular one and an Extreme beats a Hard. - Once you have dodged or fought back in a round, further melee attacks on you that round get a bonus die, so don't get surrounded. - Running away is not failure; many Mythos entities can't be harmed by ordinary weapons. - Madness is a story moment: play out the bout, phobia or mania the Keeper gives you.

Players and time

One Keeper and a small group of investigators; the Starter Set's group scenarios are written for three to five players. Chaosium suggests two to four hours for a first session. One-shots work well, and campaigns run across many sessions.

Starter scenarios

The free Quick-Start Rules include the classic introductory scenario The Haunting, set in 1920 Boston, with four ready-made investigators. The Starter Set, updated for the game's 40th anniversary, adds the solo adventure Alone Against the Flames, which teaches the rules and character creation as you play, and three group scenarios: Paper Chase, Edge of Darkness and Dead Man Stomp. After that, Doors to Darkness (five scenarios for beginners) and Gateways to Terror (three short scenarios) are good next steps.

Campaign play

Masks of Nyarlathotep is Chaosium's flagship globe-trotting campaign. The 7th edition is a two-volume slipcase set of more than 600 pages, following clues across America, England, Egypt, Kenya, Australia and China, with an optional new prologue in Peru. It is best tackled once the group is comfortable with the system and a few shorter scenarios.

Common beginner mistake

Treating Call of Cthulhu like D&D and trying to fight every threat. The rules themselves advise that running away or avoiding confrontation is generally the better idea, because Mythos entities are very powerful and often resistant to bullets. Investigation and cleverness are the intended tools.