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.