Cthulhu Style Investigations

Over the last year or two, I’ve played a good bit of Call of Cthulhu and related games. While I love many things about that particular game, I don’t like the crunchiness of the character sheet. Investigators have nine attributes before we even get to things like Sanity, Luck, Magic Points, and skills!

One thing I’ve done is play Cthulhu Dark a good bit. I stopped playing it lately in favor of my own Micro Mythos, an ultralight rule set designed to play Call of Cthulhu scenarios with simpler mechanics. I’ve playtested this with both scenarios in the Call of Cthulhu Keeper Rulebook, and it works great for that purpose. That said, it isn’t finished and I expect to publish another update in August. More coming on it soon!

Cthulhu Dark

An investigator examines documents with a magnifying glass.
Photo by cottonbro on Pexels.com

Friends have asked why I don’t simply keep playing Cthulhu Dark. It’s a good question, because that’s a great system! I’ve found that a few things hold me back from it.

One reason is that, by the end of a scenario, the Investigators likely could not survive a second one. That means it doesn’t work for ongoing play such as a campaign or even just several scenarios strung together. What about progression? Foreground growth is highly valuable to Investigators (developing contacts, gaining in-character knowledge, acquiring resources), but if we want them to continue to survive, more is needed.

Another reason is that I don’t like the fact that Investigators are lost from reaching high Insight (previously called Insanity, a change I greatly appreciate and respect). Losing your mind when Insight gets too high reflects certain implications (genre conventions, really) of cosmic horror.

So, like many others, I’ve spent some time lately thinking about how to handle these things. Perhaps we can reduce Insight after an investigation or increase mental resilience. Or we could replace Insight with some other pressure, like Stress or Heat from Blades in the Dark. Following that example, we’d just need to include some sort of downtime roll to reduce it.

Looking more closely at Blades in the Dark, when our Insight (or Stress or whatever) reaches a limit, the character disappears from the scene. In fact, we could lift the whole Stress / Trauma system from there (which in Agon became the Pathos / Fate system). Looking at the Agon approach, perhaps you can gain some ongoing benefit when your Insight reaches 6 (like a skill) but draw closer to your end.


This also got me thinking about what risks Investigators would continue to take in the game. According to the rules, they risk losing their mind upon reaching 6 Insight, but if we remove that consequence, what risks remain?

Even assuming they never fight a supernatural creature directly (which automatically leads to their death), the use of a Failure Die and appropriately-established stakes could include the risk of harm or death. If trauma (from maxing out Insight) accumulates as Conditions, and we include one Failure Die per relevant Condition, then the player still needs to manage risks but has control of when to retire.


So the next time I run Cthulhu Dark, I’m going to experiment with the following:

  • When rolling dice, on a 1-3, the result may include a Condition that affects you going forward. This risk should be established in advance before rolling.
  • Subsequent rolls may include a Failure Die for each relevant Condition. If multiple Failure Dice are rolled, use the highest result for comparing to your own highest result.
  • Conditions can be removed with appropriate fictional action. In some cases, this could include another dice roll.
  • When your Insight reaches 6, you’re taken out of action and leave the current situation. Your Insight resets to 2. Write a Condition that reflects the trauma your Investigator has suffered, such as “Shaky” or “Paranoid”. Also write a limited-scope skill, such as “Climbing” or “Intimidation”, that you developed during the investigation. This skill can be used as an Occupation die when your actual Occupation does not apply.

I’ve thought about other house rules, such as a Devil’s Bargain or clarifying when to make an Insight roll. Those concerns are separate from giving Investigators in Cthulhu Dark a bit more longevity, however.

I’d love to hear your thoughts and experiences with any of this, and if you do give Micro Mythos a spin, definitely please let me know!

One thought on “Cthulhu Style Investigations

  1. Hello Kyle, thank you for your blog, your advise and efforts and your time. I see you are a veteran writer on RPG, you have much merit. I’ve been a DnD and also Lord of The Rings player many years ago (more than 30), and I’d love my daughter could enjoy RPG as I did. Covid and videogames have damaged too much our society, It’s time to educate and give the young people a chance to dream and be happy through role-playing. Even I am thinking of writting a TTRPG game… Glad to meet you. I’ll read your posts as long as I have time for it, but I’d love to know your thoughts on this sort of gaming. See you.


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