Hacking Cthulhu Dark

by Graham Walmsley

Cthulhu Dark is a rules-light system for Lovecraftian games. It is a ‘pick-up-and-play’ system, the rules can be learnt in a matter of minutes. It’s influenced by GUMSHOE and is minimal: the rules fit on one sheet of paper.

Download Cthulhu Dark

Now, when people see Cthulhu Dark, they often get an urge to hack it: for example, by adding rules for combat or character improvement. That’s fine. Hack away. This article gives you some guidelines.

1. First, play it as written.

When I wrote Cthulhu Dark, I thought players would want many more rules. For example, I thought they’d want rules for skills and character improvement.

However, when I playtested it, nobody missed these rules. When I asked whether I should put rules for specific skills in, everyone said no.

So play Cthulhu Dark before hacking it. You may find you don’t miss certain rules. But, if you do miss them, start hacking.

2. Keep it simple.

Cthulhu Dark always favours simplicity over detail. Here are some examples.

  • If you’re adding rules for weapons, don’t list all the different guns: just give an extra die for a particularly effective one.
  • If you’re adding rules for combat, don’t give different hit thresholds for different monsters. Just set the standard hit threshold as 4.

Always keep it simple, even if you lose subtlety by doing so.

3. If a rule makes no difference, leave it out.

Let’s say you’re adding rules for Armour. When someone wears armour in combat, you want to give them an extra die.

But, in a game, won’t this make everyone wear armour? And won’t all the important monsters have armour too? Most of the time, everyone will get that armour die.

Again, keep it simple. If a rule won’t make a significant difference, leave it out.

4. Add and subtract dice, not numbers.

Let’s say you want to add rules for combat. For example, when someone has a particularly effective weapon (for example, they’re using silver weapons against werewolves or water jets against Cthonians), you want to give them a bonus.

Give them an extra die, rather than +1 to the roll. Similarly, to give someone a bonus, subtract a die, rather than giving them -1.

Why? Because the mathematics of success are finely tuned. +1 and -1 are extremely powerful. Adding and subtracting dice affects the roll, without being overwhelming.

5. When you have a pool, make it work like Insanity.

Let’s say that, for a Delta Green hack of Cthulhu Dark, you want to represent how close the Investigators are to blowing their cover.

Represent this with a die, which works like the Insanity die. Let’s call it the Exposure Die. When the Investigators do something to draw attention to themeselves, roll it: if the result is above their current Exposure, it goes up. When they do something to cover their tracks, roll the die: if the result is below their current Exposure, it goes down. When Exposure gets to 6, the Investigators’ cover is blown.

Try a similar die for Social Status in a Gaslight hack or breaching the Veil in an Esoterrorists hack.

I hope you enjoy hacking Cthulhu Dark. The hardest hack is combat. If you find a fun way to represent that, let me know.

8 Responses to “Hacking Cthulhu Dark”

  1. Tigger says:

    Combat- havent tried this but the idea floating around my head is:

    First wound – you can no longer access your specialism die. You are injured but mobile.

    Second wound – you can no longer access your “humanly possibly” die. You are conscious but no longer mobile bar crawling or small slow movements.

    Third wound – unconscious

    Fourth wound – dead.

    Improvised weapons only wound on a 4-6. Otherwise, you may hit but the victim gets the sort of scratch that doesnt impare its effectiveness (altho it may hurt !)

    Ordinary (1H, eg dagger, pistol) weapons do 1 wound and a second on a roll of 6
    2H (claymore, rifle) weapons do 1d3 wounds
    Big weapons (bazooka) do 1d6 wounds
    Huge weapons do 2d6 wounds

    Monsters have wounds (and may take reduced damage)as the gm sees fit.

    Combat round :
    Fast characters phase (some monsters, characters with combat specialism like soldiers) go first. If more than one combatant in this phase, roll 1d6 to determine order.

    Slow characters phase : everyone else. If more than one combatant in this character, roll 1d6 to determine order.

  2. Rob Harper says:

    ooooh, social standing die in Gaslight etc., that’s a golden example, love it.

  3. Sang. says:

    Why not a Health die/pool? If you fail in a fight/scape, make a Health roll. And that’s it. Use Health die like Insanity.

  4. Sang. says:

    It’s me again. The Health die is ok for a DCrawling taste. For a more crude one, use this:

    Roll for defend yourself when attacked.
    You fail once, you get Wounded. You fail twice, you get Dead. While wounded, you lose your “humanly possible” die, so you can’t success in any action you attempt unless you use your specialism or [any used pool] dice.

    If you dare to attack (you fool!), make your roll normally. Most of times, attacking a Myth is useless. If the NPC is vincible, the GM rolls a die, +1 if the NPC has a combat specialty, and +1 if it’s a Myth Creature (they ALWAYS use their Insanity Die as they can’t get madder), so we have 1-3 die for making the PC to fail his attack (and usually getting wounded)

    So: Attacking a Teacher: Against 1 die. Attacking a soldier: Against 2 dice. Attacking a killer-minded Myth: against 3 dice.

    Do you really need weapons? I think weapons are just narrative. A teacher won’t use really effectively a gun, and a policeman is already getting advantage of his specialty. I you want to make the difference between different weapons, just adjust the time a PC takes for recovering from “wounded”. Wounded by fists maybe take some hours or a couple days, Wounded by a big gun may take several weeks.

    I wrote so much but I think it’s simple.

  5. Alejandro says:

    I prefer a more “narrative” approach. The main rule stay: If your character attacks the Mythos, your character will die. But if you want a fight (for example, if you are playing a pulp adventure or The Esoterrorist setting and you want a gunfire) just declare your intent, decide what is a stake and roll the dice.

    Do you want to kill the enemy? Maybe the enemy wants to kill you. Do you want to move to a better position? Maybe if you fail the roll you’re caught between enemy fire and you jump into a pit, covering your head with your arms. Do you want to save the hostages? Then maybe something else happen if you fail the roll: the hostage is severely injured (or dead), you are injured (you get a shot in the chest and fall heavily to the ground, your vision blurs and hear screams all around you), you get knocked down and you lose your weapon, or whatever. What make sense to the situation.

    “But what happens if my character is using a bulletproof vest?” Well, maybe if you fail a roll and somebody shot you I don’t declare that your character is dead but just is knocked down. Depends on the situation, but I think if you are protected you will have a better chance of surviving. (But don’t expect much if I shot you in the head.) “But what happens if I have a better gun that he has?” Well, depends. With a pistol you can only try to kill one enemy at a time, but with a machine gun you will probably provoke a slaughter. And so on.

    To me, combat is like any other situation, and must be played like any other scene. In a gunfire you can be killed, injured or kill some innocent people by mistake. (You see the girl fall to the ground, with blood on his chest and a plush rabbit in his hand. Everything seems to happen in slow motion. Roll your Insanity die.) If you are shot in the leg now you are knocked down in the ground, yelling and cursing, and the tears flow down your cheeks. The pain is unbearable. Etc. But remember to briefly tell the players what will happen if they fail their rolls before they throw the dice. That way they can reconsider their strategies. Yes, you can do that. But are you willing to risk being shot in the leg, to give your life, to lose one of the hostages, or anything else that seems appropriate? If you are, then please throw the dice.

  6. Tim says:

    In my group, I proposed a very simplified way of doing combat.
    If a player wants to fight a monster, they basically roll a contest against it. Each side gets one die for each condition met:

    – A physical advantage, such as being much stronger or faster, or the creature being hurt or weak from something else
    – A weapon capable of harming the other side (A plastic spoon won’t do much against a horror-monster)
    – Favorable terrain (Such as fighting in a tiny cellar against a huge monster that is unable to move around effectively)

    Then whoever rolls higher wins. (And, naturally, the GM reserves the right to decide you can’t combat a specific enemy because you’re guaranteed to lose whatever you bring to the fight, or maybe giving a bonus die if the player is especially clever in their description of fighting the enemy)

    I hoped this would fit the simple way things are already done, without adding extra variables to keep track of throughout the game. It seemed heavily focussed on story and roleplaying, so I wanted to add it in a way that didn’t change that aspect of the game either.

  7. Chris says:

    I’m thinking you could pretty much use the competition system as written.

    – If it’s a creature normal humans can fight, you get a die.
    – If fighting is part of your occupation (soldier or vet, cop, PI), you get a die. (Weapons, armor, tactical advantage, blah blah blah are all covered by this die.)
    – You can use your Insanity die normally. (If it’s a creature normal humans can’t fight, this could be your only die.)

    Opponents’ die pools would be scaled from 1 (guard dog, civilian) to 6 (GOO).

    If you (PC) fail, you take a Wound (and roleplay it), but escape (or can choose to fight another round). If you succeed, you beat the NPC. At 5 Wounds, you can spend a day in the hospital; roll a die, if it’s less than your Wounds, reduce your wounds by 1. At 6 Wounds you’re dead.

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