Beginner quickstart
A fast, practical overview. Call of Cthulhu 7th Edition is a horror investigation roleplaying game based on H.P. Lovecraft's Cthulhu Mythos. Players take on the roles of Investigators—ordinary people who uncover cosmic horrors beyond human comprehension. As you investigate mysteries, your character's Sanity slowly erodes, skills improve through use, and the line between reality and madness blurs.
You describe actions, the table uses the system’s core resolution mechanic when the outcome is uncertain, and the GM applies outcomes to keep the story moving.
Call of Cthulhu uses percentile skills: roll d100 and succeed if you roll at or under your skill. Difficulty often shifts the threshold (Regular/Hard/Extreme) and Sanity loss is a core pressure loop.
You search a room fast before the cult returns. Roll Spot Hidden; a Regular success finds the clue, a failure still finds something but costs time or adds a complication.
If the clue is tiny or conditions are bad, the Keeper can call for Hard/Extreme. You’re not changing the scene—just raising the required quality of success.
Call of Cthulhu uses a d100 (percentile) system. Each skill has a rating from 0-100. To attempt a skill, roll d100. If you roll equal to or below your skill rating, you succeed. Rolling 1-5 is an extreme success (hard difficulty), and rolling exactly your skill rating is a critical success.
During play, mark skills when you attempt them (whether you succeed or fail). After each session, you can try to improve marked skills. Roll d100—if the result is higher than your current skill rating, you gain 1d10 skill points. This represents learning through experience, a core mechanic of Call of Cthulhu.
Call of Cthulhu uses eight Characteristics: Strength (STR), Constitution (CON), Power (POW), Dexterity (DEX), Appearance (APP), Size (SIZ), Intelligence (INT), and Education (EDU). Most are rolled with 3d6×5, while INT and EDU use (2d6+6)×5. These determine your derived stats like HP, MP, and Sanity.
Sanity starts at 99 minus your POW characteristic. As you encounter Mythos horrors, you lose Sanity points. When Sanity drops to certain thresholds (like 50 or 20), you gain mental disorders. Temporary insanity occurs when you lose 5+ Sanity in one session. Sanity represents your grip on reality—lose too much and you become permanently insane.
Occupations define your Investigator's profession and provide skill bonuses. Each occupation has a Credit Rating range (wealth level) and specific skills it improves. Examples include Antiquarian, Doctor, Journalist, Private Investigator, and Professor. Your Occupation Points (EDU×4) must be spent on occupation skills.