Thursday, October 2, 2014

House Rules for Combat in Call of Cthulhu

Combat is deadly in Call of Cthulhu. So the stakes are high. Close range with firearms provides enormous bonuses to hit: you literally double your skill with the weapon at close range. The result is that if you have 50% in the weapon, you only miss 1% of the time. I found that players naturally were wanting to utilize this advantage for themselves and minimize it for others by moving into and out of close range in the middle of combat. I needed some house rules on moving and shooting. Furthermore, I had an investigator who was badly injured and I wanted to introduce some official rules on injuries and recovery, so I wasn't just making it up. Here are the results. (The stuff on initiative order is by the book.)

Movement Rates:

A character can always take a 5’ step in a round, whatever else she is doing. A character can walk safely 30’ in a round. She may sprint 60’ in a round.

Order of Initiative:

Combat occurs in the order of dexterity. A player announces what her investigator will do when it is her turn to act. An investigator may defer her action to any point later in the round. She may also give conditional actions. For example, she may wait for someone else to act before she acts, or declare that she will shoot anyone who moves towards her. 

If an investigator is carrying a loaded firearm and expecting to have to use it, it is readied. Anyone with a readied firearm adds 10 to her dex for the purposes of determining who goes first, provided she is solely shooting.

An investigator charging 30’ and then attacking with a grapple or melee weapon subtracts 5 from her dex for the purposes of initiative. An investigator moving 60’ subtracts 10.

Firearms Penalties and Bonuses: 

*Note: All fixed amount penalties or bonuses are applied before scores are doubled, halved, or quartered.

Close range (=dex or less in feet) x 2 
Long range (up to twice base range) x .5
Extreme range (up to triple base range) x .25
Target has partial cover x .5
Target has near total cover x .25

An investigator may take a 5’ step and fire without penalty. 
An investigator may move 15’ and fire with a -10 penalty. 
An investigator may move 30’ and fire with a -20 penalty. 
An investigator cannot fire while running wildly.

An investigator firing at a target moving 30’ takes a -10 penalty.
An investigator firing at a target moving 60’ takes a -20 penalty.

Damage and Death:

An investigator who falls below three hit points is unconscious. 
An investigator who falls below 1 hit point is dying. A dying character loses 1 hp per round, until someone makes a successful first aid check on her.
An investigator who falls below negative two hit points is dead.

An investigator who suffers more than ½ her hp in damage receives a minor wound. This wound should have one real world consequence. Some examples: the investigator must wear the off arm in a sling or suffer pain, the investigator walks with a limp and -5 to movement, or needs to wear an eye patch and takes -10 to firearm shots, or has an obvious shiner and takes -10 to credit rating or persuade checks among high society types. 

An investigator who suffers an impale receives a moderate wound. This wound has one real world consequence and also provides -10 to all physical checks. 

An investigator who falls below 3 hp receives a major wound. This wound provides one real world consequence and also provides a -20 to all physical checks. 

*Note: The penalties to all physical checks for being impaled and falling below 3 hp stack.


Successful first aid restores 1 hp. 
Seeing a doctor or going to a hospital restores 1d3 hp (-1 if you already got first aid).  
For each week that passes after the wound, the investigator recovers 1d6 hp.
Minor wounds go away on their own in 1 week. After a week the real world consequence no longer applies.
Moderate wounds and major wounds will not heal without medical treatment. 
Penalties to all physical checks from moderate wounds and major wounds heal at the rate of 5% per week if the investigator is active. If she is in a hospital or resting at home, she heals at twice that rate--10% per week.
The real world consequence from moderate and major wounds are removed only once the entire penalty to all physical checks has been reduced to 0%.

Example: A Pinkerton with a .45 in his hand emerges from the back door of the house a mere 10' from Rust. Distracted by another investigator at first, the Pinkerton does not see Rust until he sprints 60' into the woods. Being a seasoned veteran and natural born killer, the Pinkerton's skill with a .45 is 80%. The base range of a .45 is 15 yards. The Pinkerton first takes a -20% penalty for firing at a sprinting target, so his skill check is at 60. Furthermore, after his run, Rust is 70 feet from Pinkerton, well into long range, so that is halved to 30. Furthermore, Rust has partial cover now that he's in the woods, so that number is halved again, and the Pinkerton will need to roll 15 or less to hit. Unfortunately for Rust he rolls a 12%! Rust takes a whopping 10 hp as the slug enters the back of his right shoulder! Rust had 11 hp to start, so he falls to 1 hp. Since he has fallen below 3 hp he is now unconscious, but since he is above 0 hp, he is not dying. When he regains consciousness, his shoulder injury will be a major wound, requiring medical attention, and giving him -20% to all physical checks in the near future. He'll be wearing an arm in a sling and will not easily be able to perform actions like climbing a ladder or riding a bicycle. Since he's working on a case, and cannot afford to lollygag around all day, his penalty will decrease at the rate of 5% per week. At that rate, it will be a full month before his arm comes out of the sling!


  1. My CoC experience is limited, but this seems like a good fix.

  2. Any thoughts on what edition of CoC to run if I wanted to try running the system for the first time?

  3. I just went with 2nd edition, which is what I happened to have. My understanding is that the editions didn't change very much in the first six iterations of the game. The new 7th edition, which is just coming out now is departs a bit more, for example, in how sanity works. Unlike, say, with D&D where the difference between OD&D and 3rd edition is enormous, it doesn't really matter what edition you use with CoC.