A downloadable game

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Building upon the groundwork set out in Cthulhu Dark by Graham Walmsley, Cthulhu Deep Green contains a modified rules set for playing as Agents of The Conspiracy: a shadowy government agency tasked with concealing evidence of the supernatural.

This 52 page PDF contains all the basic rules you’ll need to play,  Handler’s advice for running your own scenarios, and tables to help inspire play. Playable with three to six players with sessions lasting two to four hours.

Also included: Food of the Gods, a fully realized scenario set in the Seattle underground dining scene. 

With a focus on quick setup and improvisational campaign play, the rules of Cthulhu Deep Green are designed to focus the human element while keeping the action tense and dramatic.

What will your agent give up to protect the public from terrors beyond sense or reason?

Pick up your phone and report in.

Author's Notes: 

This material has a general content warning for depictions and allusions to violence and psychological manipulation.

Unlike similar games, CDG steps away from references to sanity and insanity but it does deal with stress related disfunction and issues of work-life balance.

I reserve the right to update these files periodically with new material.  Follow this account for updates.


7x10 print copies of Cthulhu Deep Green are now available via DriveThru!

Unofficial CDG Soundtrack


Buy Now$7.00 USD or more

In order to download this game you must purchase it at or above the minimum price of $7 USD. You will get access to the following files:

CDG PDF.pdf 53 MB
CDG Spread.pdf 66 MB
Food of the Gods.pdf 25 MB

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Download demo

CDG - Rules Preview.pdf 1 MB

Development log


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In Rolling the Dice, the third paragraph reads:

"They may roll one Occupation Die if the action falls under an their personal field of expertise."

I'm not sure what "under an their" is supposed to say, but it reads like there's a typo or word missing or similar!

Love the book!


If an Agent isn’t happy with the result of their roll they may take up a singl DARK DIE, along with any other dice already invoked, and try again. Agent's may do this as many times as they desire, but they risk Insight and/or Stress each time. 

Typo: "single"

Grammar: "Agents" (drop the apostrophe)

(Hopefully this is useful, and not annoying!)

To tie things together, play up the mystery of The Organization, introduce ongoing issues At Home, and build upon each mission’s successes and failures with news commentary or a pre-session recaps. 

Drop the "a" from "a pre-session recaps"

I’d prefer stuff like this went directly to email, rather on the store page, but I’ll happily implement any corrections in the next update.

Sure thing! I can remove the comments, if you like! 

New layout is excellent btw

Using the spreads PDF on my desktop monitor is very nice - my compliments.

(4 edits)

Q) Thoughts on using a harsher die-results format, and removing the failure die mechanic?

1-3 = failure
4-5 = success with complication
6 = success
More than one six = critical success

Would trigger more re-rolls, I'd imagine

I haven't played it yet, but it looks great.  The rules are really easy to grasp and fit the theme well.  I much prefer the simplicity of these rules to the complex rules of other Cthulhu mythos games!

Q) What in-game effects do Injuries and Debilities apply? Justify a Failure Die?

They might, though remember a player needn’t justify a failure due beyond the idea that it makes a roll more interesting.

Primarily they put a limit on how much violence an Agent can participate in. Each slot can only hold a single injury and a level three injury takes you out of the action without immediate treatment so they act to encourage players to seek more clever or non-violent ends to an operation. If you’re The Handler, don’t be afraid to threaten players with very serious injuries if they partake in violence.

As for the flashbacks: I’ve found them to be much more interesting in Playtest than the previous resource mechanic. They allow players to explore how they feel about horrific events on a personal level and flesh out their characters before they die horrible deaths, which makes the bad things that happen to them all that much more awful.

(and thanks for the typo, I’m currently editing this doc a bit to get ready for a potential print on demand version so I’m actively doing editing and revision of the docs over this next week!)

The process of marking Anchors is not in the latest version of these rules. Can you please update?

(1 edit)

The rule has been changed! It's a brief rule now, but an improved one:

PG. 14, At Home Scenes

"At home scenes are activated in one of two ways:

Once, after a mission.

Or when Agents mark an Anchor."

In a future revision I'll consider making a reference to this rule in the anchor section!

PS: I added a clarification to the character creation section under “Anchors.”

AFAIK it doesn't explain the purpose of marking an anchor (previous version stated it's to prevent Stress/Insight increasing)?

Correct on the previous version. It should now say 1. That you can activate an At Home scene by marking an Anchor in two places:

Right - I get it now! I think my awareness of the previous rules meant I was laboring under a mis-understanding.

"Anchors may be marked to falashback and activate an At Home scene at any time."

(Spotted a typo above, btw!)

I should have read fintcher's thread below more closely - apologies for my obtuseness.

From your playtesting, how did the flashbacks go in terms of potentially disrupting the flow of the horror? Like, you're at some climax to the story, and a PC who has a high stress marks an anchor and triggers a flashback to wandering fields of flowers with his girlfriend? Jarring or not?

Love the game. In particular the cover and exposure track.

Question: can destroy the unnatural treat reduce the insight? Like roll a D6 and if it's lower than your current value you reduce insight by one. Cthulhu Dark has a similar mechanics to "repress knowledge"

Thank you so much!

To answer your question: No, Insight is permanent and acts as a sort of marker for how far gone your Agent is. In general, depending on the operation, Agents should face a lot fewer Insight checks than Stress checks, though.

That said, if you prefer Cthulhu Darks suppression rules there’s no reason you couldn’t tack them on for Insight checks and I do have plans for some more optional rules along these lines in a future supplement.

Oh no I like it, also because you have removed the insight on 6, and now you have the stress for "normal" situation, just curious if you were planning "sanity" rewards for doing a good job (either reduce Insight, or the stress or Unmark an Anchor)

The other question was about the home scene: you can activate one in play by crossing an Anchor, so I guess the only one that makes sense is "Engage in Self Care", since the others don't involve your Anchor (and the stay on the case one is something you are already doing while playing). Besides that I love it: adding a clock for exposure is genius, we were thinking to do something similar playing CoC and DG to "dump" the failure in rolls that succeed no matter what (like forcing a door, you will succeed but someone will see you)

Crossing an Anchor allows you to play out any of the At Home Scenes (though repairing an anchor would be a bit recursive) so long as you include them in some way!

Presumedly they are a big part of your Agents life, so bringing them up in therapy, having them visit you in the hospital, or being an important part of your self care are all pretty likely.