A downloadable game

Buy Now$7.00 USD or more

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 dysfunction and issues of work-life balance. I reserve the right to update these files periodically with new material. Follow my account for updates.



The fictional premise of CDG is heavily inspired by the Call of Cthulhu roleplaying game, published by Chaosium, as well as Delta Green, by Arc Dream Publishing. I encourage you to check out and support both games!

And, as stated above, CDG is a hack of Cthulhu Dark by Graham Walmsley designed with the intent to expand the fictional scope and allow for more direct campaign play. You can support Graham on DriveThru right here!

Printed Copies

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

Unofficial CDG Soundtrack

CategoryPhysical game
Rated 4.9 out of 5 stars
(37 total ratings)
GenreRole Playing
Tagscthulhu, Horror, Psychological Horror


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 Spread.pdf 27 MB
CDG PDF.pdf 23 MB
Food of the Gods - Spread.pdf 15 MB
Food of the Gods.pdf 15 MB

Community Copies Project

Support this game at or above a special price point to receive something exclusive.

Free Copies

Every full-price copy of Cthulhu Deep Green you buy helps someone else grab a free copy if their budget doesn't enable them to pay the listed price. If you're unable to budget for a copy of Cthulhu Deep Green priced as listed, please claim one of these free copies for the community.

Download demo

CDG - Rules Preview.pdf 1 MB
CDG Google Sheets

Development log


Log in with itch.io to leave a comment.

Really liked the concept of the game, might run it with my group and check it out, the whole vibe is amazing!

Can you please explain the "ROLL 6d6 TO DETERMINE ITS CONTENTS" part as this makes no sense to me.
You clearly aren't rolling 6d6 and adding them together because the table goes from 11-66 and that would be a table between 6 and 36.

This would make sense if it said something to the effect of "roll 3 times, 2d6 and treat whichever dice is to the left as a ten's die" but it doesn't say that and as a result to anyone who doesn't recognize how this is supposed to work it is liable to end up confusing.

The Safe Box table is neat but I think it needs a rules revision to better explain itself.

So this is a classic table format some folks use in games that only use d6

Basically there are 36 choices (6x6 is 36) and to determine your selection you roll 2 six-sided dice and count them as digits. One in the tens place, the other in the ones.

p. 7's example; "If they had rolled a 4 or higher, both Stress and Insight would have increased." - If Stress=4, then rolling a 4 shouldn't increase Stress? Should the example say, "If they had rolled 5 or higher"?

In CDG stress and insight are raised when the dice are equal to or higher than the current value!

(3 edits)

p. 5: "If the DARK DIE rolls highest AND it is higher than the Agent's current Stress value,
Stress is raised by one."

Edit: As an aside, I'm assuming highest !== "equal highest" (same as Cthulhu Dark)?

It actually does mean equal to or higher. If you roll two sixes and one is the dark die, dark die is the highest value! The example quoted previously is meant to clarify that, though I can understand that there might be confusion.

Howcome Food of the Gods is spreads only now? I'm sure I'd previously downloaded a singles version.

Ah! Apologies. I’ll fix that later today ✨

That’d be grand. Thanks

I've uploaded a single and a spread version along with some minor updates to the format and text! Enjoy, and be on the lookout for The Linear Men: https://moth-lands.itch.io/cthulhu-deep-green/devlog/171830/cdg-updates-the-linear-men-coming-soon

(5 edits) (+3)

Cthulhu Deep Green is a 52 page espionage horror game that splits the difference between Cthulhu Dark / Delta Green.

It has solid layout and artwork, it's very readable, and it steers in a slightly different direction than the modern Delta Green books---keeping the same overtones, but making a choice on whether to focus on storytelling or crunch.

The mechanics are simple but have some meat to them. If you're not familiar with Cthulhu Dark, you roll a d6 and on any result, you succeed. 1--3, it's with a complication. Higher than that, it's as you intended, or with an advantage. You can add more dice if your profession applies, and you can add more dice if you're willing to risk your mental state and physical safety.

This emphasis on failing forward makes Deep Green a game where your PCs can have agency, and where they're likely to find the heart of a given mystery---even if they don't overcome it---as opposed to Delta Green's tendency towards one minor misplay obliterating the agents before they know what they're dealing with. I admittedly like both styles, but Deep Green is definitely better if you want to decrease the overall randomness in your stories.

That said, combat and sanity are handled in a bit of an odd way.

With combat, any time you describe a course of action leading to violence where the outcome is uncertain, you fail and are killed. You can choose to rewind time and try to avoid violence, and in which case there's only a 50% chance that you are killed. Granted, the GM can simply wound you instead of killing you, but it means you have to do a *lot* as a player to make sure the outcome is never uncertain if you want to oppose other violent characters or monsters.

Sanity, meanwhile, is handled through the accumulation of stress. Stress builds up when you risk your mental state on rolls, and if it gets high enough, you take a disorder. Disorders can be treated, and agents are way more mentally resilient in Deep Green than in DG, but they also have a separate track, Insight, which progresses them towards oneness with the Mythos and a dramatic exit from the game.

Both mechanics are interesting, but I think I'd urge the GM to be lenient with situations involving violence. Make 'minor injury' your go-to when a PC gets in a fight, and save the 50/50 deaths for when they try to fist-fight Hastur.

Deep Green also has something similar to DG's downtime and bonds system, with the catch that Deep Green's works. Instead of your actions between operations mostly being useless / a way to showcase your descent into personal tragedy, almost nothing's random in Deep Green's At Home time. Restoring a bond just works. Fixing a disorder just works. Lowering your Stress doesn't instead sometimes raise your Stress or have the GM assassinate your PC. It's a breath of fresh air.

Setting-wise, there's very little distance between Deep Green and DG, and Deep Green could be used to play basically any DG scenario. The few hints at difference (terms like 'illuminated', and an actual rulebook for agents) are nice, but I found myself wishing there was a little bit more to set Deep Green apart.

Fortunately, Deep Green comes with an 18 page supplement, Food Of The Gods, that partially scratches that itch. Food is a solid, low-lethality scenario that can still scale up to challenge seasoned players. Some GM interpretation might be needed for how one of its key elements works, and the GM may need to prompt groups that get lost, but Deep Green's fail-forward approach should keep the players pointed straight at the heart of the adventure.

Overall, if you like shows like True Detective and X-Files, if you like Delta Green, if you enjoy Call of Cthulhu or Cthulhu Dark or Trail of Cthulhu or Night's Black Agents, or if you just want to play a tense, immersive game of modern occult conspiracies, there's something for you here---although whether it's your thing or not is going to depend on how much crunch you need. For me, the simplicity of the dice added to the intensity of the game, and I would strongly recommend it to anyone who's even a little bit interested in picking it up.

Minor Issues:

-Page 16, first para, "Burning out" Out

-Page 24, Specialty Skills feels like it breaks verisimilitude a little bit, with getting scuba training making you unable to set bombs, or vice versa. Maybe picking up Specialty Skills could be an At Home action?

-Page 23, there isn't any indication for how to mechanically remove ticks from the exposure clock. Would At Home actions do it?

-Page 47, the font randomly changes here. Intended?

-Food page 10, "(it like honey and fish)" smells like?


Thank you for the review. I really appreciate it! 

And I’ll see what I can do to address those errors mentioned at the end! For those products where I’m basically a one man production crew it can be tough to catch them all ✨


No worries. I try to document stuff as I spot it, but everything I saw here was completely minor.

So this is basically a Cthulhu Dark version of Delta Green, right?  

I think you’ve got the idea ;)

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.