Today we’ll be taking a look at the mechanic that pretty much made Call of Cthulhu unique: Sanity and Sanity Loss.

But before that, it’s important to note that Sanity as it is portrayed in Call of Cthulhu is not meant to simulate real-world psychological trauma. Instead, it helps to view it as an approximation of how H.P. Lovecraft’s protagonists react in the face of horrifying sights and terrible creatures.

Sanity as Mental Resilience

Mechanics-wise, sanity is your “mental HP” as your Investigator is hammered with encounters involving the horrifying and alien, they are often called to make Sanity Rolls. These checks determine if the character is able to lessen the blow of the Sanity Loss, or takes a bigger hit.

Taking Sanity Loss is a dicey proposition at best, with successively more dire consequences depending on the amount lost and in how short an amount of time. The effects range from involuntary actions, to temporary insanity to being reduced to a permanently insane individual.

Effects of Insanity

As described above, there are a LOT of different things that can happen to an Investigator. Some of these might even mean temporarily surrendering control of an Investigator to a Keeper, or altering background details of an Investigator with irrational entries.

After a bout of madness, the player regains control of the Investigator but now usually has some sort of underlying madness still present. This means that the Investigator may yet slip into more outward manifestations of it should their fragile psyche be bombarded with another mind-blasting encounter.


Thankfully, there are ways to arrest Sanity Loss. Temporary Insanity is resolved with some peace and quiet and decent rest. More… persistent forms of Insanity require Institutionalization.

The Sanity Mechanic is perhaps one of the greatest claims to fame of Call of Cthulhu as a system. While other games have different takes on sanity these days, Call of Cthulhu’s system is elegant in play, and the random nature of how much sanity you lose in an encounter keeps things unpredictable.

In many ways, Call of Cthulhu’s ruleset may be a bit old, but the 7th Edition retains much of what made it interesting in the first place. The mechanics enforce the classic elements of horror: Helplessness, Lack of Knowledge about the Enemy and Fragility, which make it very potent in play.

If you’d like to read along, you can pick up a PDF copy of the Call of Cthulhu Keeper’s Rulebook from DriveThruRPG for only $27.95


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One of the more interesting details I’ve come to realize about Call of Cthulhu is that running away is a completely valid means of managing a situation. It stands to reason then that Call of Cthulhu should have mechanical backbone to support it.

I don’t think I’ve seen this much mechanical emphasis on chases in another game outside of Spycraft, which is another genre that highlights the value of a well run chase scene as a source of conflict and tension.

Mechanically, Chases are handled with a more involved turn-by-turn system that works by establishing relative speeds, relative positions, obstacles and rules governing actions taken during the chase scene that could result in injury or capture.

Tracking is handled on a linear track, as opposed to a grid map. I actually prefer this method as it saves on table space while still being able to keep track of where everyone is.

Beyond this is a large number of optional rules that cover everything from passengers, collisions and sudden hazards and obstacles. It’s extensive, and I’m glad that there’s a lot of them there in case you’ll need something that you didn’t expect like air and sea chases, or even mixed chases.

Few things capture the nature of primal terror better than watching someone try to outrun near-certain death. Horror movie moments aren’t made from the protagonist kicking ass, but pulling off narrow escapes. Call of Cthulhu acknowledges this by giving systems that cover this conflict with the kind of attention it deserves.

If you’d like to read along, you can pick up a PDF copy of the Call of Cthulhu Keeper’s Rulebook from DriveThruRPG for only $27.95

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Today we’re talking about guns in Call of Cthulhu. While largely ineffective against the truly awful horrors of the Cthulhu Mythos, it doesn’t hurt to be carrying a firearm of some sort against the more human cultists that often attack the Investigators.


As mentioned in our previous post, Firearms Skill Rolls do not used the Opposed Roll variant of the rules. Instead, it is a straightforward Skill Test modified by both the Difficulty of the test, as determined by range, and other factors, which manifest as Bonus or Penalty Dice.


Range Penalties

Each ranged weapons has a Base Range statistic that is used to determine the range categories of a given weapon. Each range category beyond the Base Range increases the Difficulty level of the shot by one step:

  • Within Base Range: Normal Difficulty
  • Up to twice Base Range: Hard Difficulty
  • Up to four times Base Range: Extreme Difficulty

Firearm Attack Modifiers

Modifiers to Firearms attacks all take the form of Bonus and Penalty Dice. These cover cases such as aiming (which gives a Bonus Die to the roll) to firing multiple shots (with a Penalty Die for each shot made.)

Automatic Fire

Some weapons in Call of Cthulhu are capable of Automatic Fire, an option that might not be the most accurate, but it certainly can come in handy when faced with hordes of cultists or a monstrous horror the size of a house. A character armed with an SMG or MG may fire a volley of a number of bullets equal to their firearms skill, divided by ten, rounding down.

When firing full auto or in burst mode, then the first roll is treated as a standard firearms roll, but each successive volley is penalized by up to 2 Penalty Dice, and an increase in the roll’s Difficulty after the first 2 Penalty Dice.

If the attack roll was successful, then it is assumed that half the bullets of the volley have struck the target, and the attacker rolls for half the number of shots in the volley.

If the attack roll was an Extreme Success, then it is assumed that ALL bullets in the volley strike the target. The first half of the volley are treated as an Impale, and the rest are rolled. Needless to say, against most human targets this is pretty fatal.


Wounds are a reality in Call of Cthulhu. Even the hardiest of Investigators will only have about 13 or hit points, so knowing how close you are from death is something that is always on everyone’s mind.

Regular Damage and Major Wounds

When an attack lands and deals damage, the first check is to see if it is Regular Damage, a Major Wound or instant death.

The least of these would be Regular Damage, and has no further effects adverse unless it drops the character’s HP to zero whereupon they fall unconscious.

A Major Wound has the character immediately falls prone, and the player must make a check to determine if the character remains conscious. If an attack drops the character’s HP to zero while they have a Major Wound then the character is considered to be dying.

If the damage dealt by one attack is more than the maximum HP of the target then the character dies.

First Aid and Recovery

Receiving First Aid while dying will stabilize the character. This buys the character time as they only need to make a roll every hour to check if their condition deteriorates. If they fail the roll, then they are considered to have slipped back to dying.

It’s because of this that after being stabilized by First Aid, it is important to follow up with a Medicine roll after to change the character’s state from Dying to Unconscious. This however, does not remove the Major Wound.

Major Wounds do not get removed from the character until:

  • The player making the recovery CON roll is able to roll an Extreme Success OR
  • The character manages to heal more than half of their maximum HP

Needless to say, getting injured means being left on your back trying to recover. Healing times aren’t fast in Call of Cthulhu, so it’s a good idea to have a few backup characters to go sending off into danger while your previous one is busy trying to rest up and letting his body knit together broken bones.

Next up, we’ll be taking a look at Chase rules, something that feels appropriate for a horror setting where running away is an important and respected survival strategy.


As demonstrated by this team of savvy veteran investigators!

If you’d like to read along, you can pick up a PDF copy of the Call of Cthulhu Keeper’s Rulebook from DriveThruRPG for only $27.95

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Welcome back and Happy Valentine’s Day!!

This is where we get a bit more involved as we tackle Call of Cthulhu’s resolution system for Opposed Rolls and Combat. Hope you guys have some coffee or tea with you, because we’re going to hit the ground running.

Opposed Rolls

Call of Cthulhu uses Opposed Rolls mostly for Player vs Player situation, or in Close Combat.

Opposed Rolls are straightforward: The participants have a mutually agreed goal where one wins and the other loses. They both choose a skill to use (with approval of the Keeper) and roll off and compare results.

Opposed Rolls have six possible outcomes: from a Fumble to a Critical Success.

Both rolls are compared to each other, with higher rolls beating lower ones. (Extreme Successes beats Hard Successes, etc.)

Bonus Dice and Penalty Dice

Opposed Rolls also have a sub-mechanic for accounting for bonuses and penalties to rolls in the form of Bonus and Penalty Dice. Both of these function by adding an additional 10’s die which is rolled alongside the d100 for a Skill Roll.

Bonus Dice allow the player to choose the lower of the 10’s dice to count for the roll, while Penalty Dice force the player to choose the higher of the 10’s dice to count for the roll.

Given the math behind this, it’s important for the Bonus and Penalty dice to represent a significant advantage or disadvantage before they come into play.


Alright, now that we’ve got Opposed Rolls squared away, we can move onto the Combat Rules.

Declaration of Intent

I find myself really liking this particular “rule” in combat: declare intent first. On each player’s turn, the player is prompted to describe what it is that their character is doing in a narrative fashion rather than a mechanical one.

This sounds pretty obvious, and many groups already do this, but it does help the Keeper come up with the Skill Roll required for the action, and helps keep everyone in the story rather than devolving to just looking at numbers.

For a horror game like Call of Cthulhu, this is key.

Fist Fights

The first(!) combat iteration we’ll be tackling is a standard unarmed hand-to-hand combat situation.

These attacks are resolved as an Opposed Roll, where the character being attacked has a choice to try and fight back, or to dodge the attack. This distinction is important as it changes the skills used in the Opposed Roll: Fighting vs. Fighting, or Fighting vs. Dodge

Fighting Back

When fighting back in Call of Cthulhu is that the winner of the Opposed Roll deals damage to the loser. Ties go to the attacker.

Dodging the Attack

If the target chooses to Dodge instead, then the game resolves more like traditional systems, where if the attack rolls better, they deal damage. If the dodging character rolls better, then they avoid damage. Ties go to the defender.

In both cases, if both combatants fail, then no damage takes place.

Damage and Weaponry

Damage for standard unarmed fighting is 1d3 plus any damage bonus from the character’s attributes. Melee Weapons have their own damage stat and are further modified by the character’s damage bonus.

Extreme Damage and Impales

On a successful hit with an Extreme Success, the attacker deals maximum damage and maximum damage bonus (if applicable). However, if the weapon used in the attack can “Impale” such as a knife or a bullet fired from a gun, then the attack deals maximum damage, and an additional damage roll for the weapon (without a damage bonus.)

Fighting Maneuvers

Any action that involves a goal other than simply dealing hand-to-hand damage is categorized as a Fighting Maneuver. This can be anything from disarming an opponent to throwing them out a window.

That was quite the handful. There are some rules bits here that I liked, such as the option to fight back and deal damage on a successful defense, as opposed to waiting for your turn to come around. If anything it shortens combat and raises the stakes and the tension of combat scenes, even for hand-to-hand combat.

Next up, we’ll be taking a look at Ranged Combat in Call of Cthulhu, which, unlike Hand-to-Hand, is not treated as an Opposed Skill Roll.

If you’d like to read along, you can pick up a PDF copy of the Call of Cthulhu Keeper’s Rulebook from DriveThruRPG for only $27.95

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Now that you’ve had a chance to look at how Character Creation works in Call of Cthulhu, let’s start with the rules in the 7th Edition.

The Skill Roll

Call of Cthulhu is a game that relies mostly on percentile (d100) dice. Damage and some other effects are determined by other dice, but the pass-fail mechanic for most of the game relies on a simple percentile roll vs a difficulty set by the Skill of the Investigator.

While this is called a Skill Roll, this mechanic also applies for Characteristics rolls as well.

Determining the Difficulty of the Roll

Skill Rolls come in three types:

  • Regular: Equal to, or below the Skill or Characteristic. This is the most common setting for majority of the rolls called for in the game.
  • Hard: Equal to, or below half of the Skill or Characteristic. This task would challenge a professional, and should only be encountered occasionally.
  • Extreme: Equal to, or below a fifth of the Skill or Characteristic. This would challenge even an expert, and should be a very rare and reserved for truly desperate situations

The Keeper determines the difficulty of the roll, and it’s important to remember if a task is easy, no roll is required.

Opposed Roll Difficulties

Should an Investigator find himself in opposed by someone else, then the difficulty of the roll is determined by the skill level of the opponent:

  • If the opponent has a skill of below 50 or less, then the roll is made against a Regular Difficulty
  • If the opponent has a skill equal to or above 50, then the roll is made against a Hard Difficulty.
  • If the opponent has a skill equal to or above 90, then the roll is made against an Extreme Difficulty.

Call of Cthulhu prefers to take the stance where the players are the ones that roll. Keepers should frame checks from the point of view of the player. An example would be that the players roll Stealth if they’re sneaking up on an opponent, but roll Spot Hidden if the situation is reversed and someone is sneaking up on them.

Success, Failure and Pushing the Roll

In Call of Cthulhu, Skill Rolls basically has the standard Pass/Fail result, but we go one step further by allowing Investigators to re-try a failed test by Pushing the Roll. When Pushing the Roll, the Investigator invests extra time and effort in an attempt to defy failure and eke out victory from a bad situation.

The stakes get higher when pushing a roll, as the Keeper is actually mandated to foreshadow the consequences of failure, which is essentially a means by which the situation gets even worse than a standard failure.

Group Rolls

In some situations, multiple characters can end up rolling. Either due to cooperation, or in order to all try to pass a test. The game provides a few helpful examples of both, and how the Keeper can rule as to what constitutes failure or success.

In cooperative tests, multiple players can roll, and if one of the Investigators succeeds, then the group is considered to have succeeded. However, in tests that involve all the players succeeding the test, such as individually making stealth rolls to try and go where they’re not supposed to as a group, then all the Investigators are discovered when one fails.

Critical Successes, and Fumbles

Rolling a 01 is a reason for celebration, and means that the Investigator making the roll achieves an improved success. Meanwhile, rolling a 96-100 is a Fumble for skill rolls with a difficulty of below 50, and rolling a 100 is a Fumble for skill rolls with a difficulty of 50 and above.

Luck, Know, Intelligence and Idea Rolls

In addition to the Skill Rolls, Call of Cthulhu is also equipped with a suite of key rolls that Players and Keepers can call on:

  • Luck Rolls are called by the Keeper and are used to simulate the fickle nature of fate. Is there a crowbar nearby the unarmed Investigator that was ambushed by cultists? Call for a Luck Roll.
  • Intelligence Rolls are called by the Keeper to determine if the Investigator can find the solution to a puzzle or or riddle.
  • Idea Rolls are called for by the Players when they’re stymied in their investigation. This will help the players get the investigation back on track, rather than hitting a brick wall. Failing an Idea Roll doesn’t mean that the investigation stalls, but rather the cost of getting back on the trail will be more costly.
  • Know Rolls are used to determine if an Investigator would be aware of a particular piece of trivia or information that they might have run into through their Education.

Overall, Call of Cthulhu isn’t a complicated rules system. Percentile systems have always been neat in the sense that even those who aren’t used to RPGs understand how good an Investigator is at a skill just by eyeballing the rating.

That said, there’s quite a few rules gimmicks (Luck rolls and the like) that exist in Call of Cthulhu’s system, and it helps for both the Keeper and the players to know what options they have available to them so they’re never unarmed.

I like that there’s a slant towards being able to keep an investigative trail alive despite failing a test. It keeps players from being too frustrated and doesn’t end a game purely on the basis of bad die rolling.

Next up, we’ll continue the rules as we look into Opposed Rolls and Combat!

If you’d like to read along, you can pick up a PDF copy of the Call of Cthulhu Keeper’s Rulebook from DriveThruRPG for only $27.95