Call of Cthulhu House Rules

The main problem with the Call of Cthulhu roleplaying game system is that it has only a half-baked method of character advancement used in campaign play. The rules work perfectly for one-off or roleplaying convention scenarios but the campaign rules are fairly poor.

At the time of the game’s initial release in 1981, it was considered revolutionary. Characters are definitely not cut from the same heroic cloth as, for example, Dungeons and Dragons characters. Characters do not increase in levels but in knowledge and this is tied to a parallel decrease in sanity and ability to interact with the ‘normal’ world. Players had a chance of increasing the skills of a character that were used in the adventure and, if the party thwarted Mythos evil, to regain some of the sanity they lost in the process.

Twenty years later, the roleplaying community has more than it’s fair share of games in which the characters are trapped in some sort of bleak situation where the best they can hope for is to postpone the inevitable. Players are firmly wedded to the idea that they can improve their characters in ways which they think will help them in future adventures. They do not like random or untargetted improvements.

Further, the idea of regaining sanity (SAN points) at the end of the adventure runs counter to the world view espoused by H. P. Lovecraft and his circle in their Mythos tales. Their character did not feel better that they had temporarily thwarted the plans of the Great Old Ones. They trembled in fear than such things existed and were patiently waiting for another chance.

The result of these rule modifications is that characters’ descent into madness is quicker but this is balanced by their increased competence in fighting the Mythos.

Skill Advancement

I propose that skill advancement in a campaign occur in this manner:

  • Players tick appropriate skills as per usual and at the end of the adventure roll percentile dice for each ticked skill to check whether it increases. Rather than the variable increase of 1d10 (1d6 – depending on which version you play) percentage points, the increase is fixed a five percentage points. This makes each increase in a skill a significant improvement in the chance of using that skill in future adventures.
  • Player may add five percentage points to skills of his or her choice in lieu of regaining SAN at the end of the adventure. The number of skills which may be increased in this way is equal to the possible amount of SAN which could be regained divided by five, dropping all fractions.
    SAN Gain Skill Raises
    1d4 No skills
    1d6 One skill
    1d10 Two skills
    1d12 Two skills
    1d20 Four skills
  • A skill may be increased by more than five percentage points in a gaming session. This means that a character may choose to increase a ticked skill that has already been raised in this adventure.
  • Any skills which have a restriction on how they may be increased retain these restrictions. For example, Cthulhu Mythos skill may only be increased by reading arcane tomes and by experience. It cannot be increased in lieu of regained SAN.