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Now Available In Print! Cthork Borg Softcover And Hardcover


Cthork Borg is a full conversion hack that adapts MÖRK BORG to a jazz age cosmic horror setting.

With it, you get 120 pages of game, including:

  • Lightly overhauled core rules, emphasizing resources and decision-making
  • d6 new classes: Socialite, Crook, Academic, Innocent, Accursed, and Complicit
  • New weapons, armor, tools, vehicles, and allies, updated for the 1920s 
  • Stability and Social Standing systems
  • A new magic system and two new spell lists
  • Occult artifacts that slowly reveal their secrets as you cling to them
  • A full bestiary, complete with 9 gods and their terrestrial servants
  • And a starter scenario, Whispers In The Mountains


CW - The usual MÖRK BORG grimness, plus references to 1920s medicine, crime, and mental health issues.


Other Cthork Borg Material:


What People Are Saying About Cthork Borg:

  • "A full adaptation of the Mörk Borg core system for weird, investigative horror in the early 20th century." Ex Libris Mork Borg


Making Your Own Cthork Borg Content:

  • Cthork Content has to abide by the overarching Mork Borg License (which is very creator-friendly!) but I'm happy to provide support for making Cthork-specific things.
  • If anyone wants to work with the same color palette, the black pages are RGB 0, 0, 0, the gray pages are RGB 231, 232, 233, and the green is RGB 0, 167, 53


For My Other Mork Borg Full Conversion Hack, See Pharmagothica:



  • As of 8.23.21, Cthork Borg now has a character sheet!
  • As of 9.9.21, Nerve Tonic, Cough Syrup, and Household Pesticide have been slightly tweaked. Fleeing has been clarified.
  • As of 9.10.21, Stability tests re: monsters have been clarified.
  • As of 9.11.21, Starting Hit Points now rolled or flat, language clarified.
  • As of 9.20.21, the most embarrassing possible historical error has been fixed.
  • As of 9.25.21, fixed a typo, added clothing and matches to starting gear, added light sources to several tool kits, and significantly improved the Complicit's benefits for choosing the King In Yellow.
  • As of 10.16.21, credited more playtesters, made minor cosmetic edits.
  • As of 10.21.21, clarified the rules on the Getting Better page.
  • As of 10.31.21, fixed a typo, clarified interaction between armor and bleed, and changed Stability loss to panic at two instances in the scenario in keeping with the clarified Stability rules.
  • As of 11.13.21, swapped the places of Academic's Well-Read and Field Of Study, giving the Academic more flexibility as a class.
  • As of 12.16.21, clarified rules for dodging and resisting spells.
  • As of 12.26.21, cosmetic edits, nerve tonic nerf tonic, cough syrup now worth drinking.
  • As of 1/8/22, clarified Carrying Capacity re: infinite backpacks
  • As of 2/21/22, added more hyperlinks, fixed minor typo, players can no longer sell Ability points into the negatives during character creation
  • As of 11/19/22, properly bookmarked the PDF, re-linked all hyperlinks


MÖRK BORG Third Party License - Cthork Borg is an independent production by Richard Kelly and is not affiliated with Ockult Örtmästare Games or Stockholm Kartell. It is published under the MÖRK BORG Third Party License. MÖRK BORG is copyright Ockult Örtmästare Games and Stockholm Kartell. For further details about the MÖRK BORG Third Party License, see https://morkborg.com/license/

CategoryPhysical game
Rated 5.0 out of 5 stars
(29 total ratings)
GenreRole Playing
Tagscore-book, cosmic-horror, hack, Historical, jazz-age, mork-borg, Survival Horror, trpg


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:

Cthork Borg Character Sheet 8.23.21.pdf 184 kB
Cthork Borg 11.19.22.pdf 18 MB

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I've been devouring Cthork Borg and it's plentiful supplements lately and am so impressed by the wealth of ideas you have, both in tweaking/suiting the Mork Borg core system and in making it something unique and your own. That you continue to deepen this well with expansions continues to surprise and delight me, there's so much great stuff there to learn from and have the most immersive game possible. Always impressed by a Richard TTRPG but this (and pharmagothica) are at the top of my list.

Whoah, thank you! Glad you've been enjoying it!


What is this!? Now also on GoodReads!??



Thank you for your work!

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Hello!  Question/thought about Omens in Cthork Borg: if the player-characters get around 4 or 5 Omens each, and you've got four players at the table...isn't that roughly 16 to 20 re-rolls or Difficulty Number reductions, etc. per scenario?  Is there a concern that so many Omens being available to the party per investigation/scenario that the player-characters will steamroll the opposition with that many 'bennies' available to the group?  Thus lessening the horror feeling of it all?  Would be eager to hear your thoughts...thank you!

Yep! More players means more Omens, more Actions in combat, more equipment, etc.

It also means you have more room to play a bit mean as the GM. You can throw more dangerous situations at them, include enemies with strong attacks or nasty gimmicks, use cults that are tactical and smart, etc.

You can definitely reduce Omens if you want to, but my experience is that this makes the game feel a little more random. The fewer Omens the players have, the easier it is for them to get picked off by a couple bad rolls.

Also, some of this will depend on the tone you want to go for. If you like tense, desperate, anyone-can-die style scenarios, you might want to reduce everyone's starting Omens by -3. The current starting Omens is a little bit more geared towards adventure pulp.

I haven't experimented with this specifically, but if you really want Omens to scale with group size, you might try -1 Omen for all players per group member over 3. That'll give bigger groups an advantage in numbers, but anyone who gets isolated will be in more danger.


This is great - thank you!  I was thinking about the Omens overnight, and am reminded by way of your response about Luck Points in Call of Cthulhu.  In that game, investigators get to cannibalize their Luck scores to directly influence dice rolls, thus working in intent and manner very akin to Omen spending in Cthork Borg.  And your point about playing the opposition as craftily and mean as possible is well taken, since Cthork Borg players can attempt to mitigate disaster with Omen spends.  In my last Cthork Borg game, my players were slinging a bunch of Omens around to defeat the opposition at the finale of the adventure and keep their own fat out of the fryer.  Thank you sir for a) a great game like Cthork Borg; and b) a speedy and thoughtful reply to my observation.  I love this game!

(2 edits) (+1)

Currently playing through "Whispers in the Mountains" and having a blast!  Cthork Borg is terrific!!!  We have two players as investigators and myself as keeper of the mysteries.  One investigator is an Innocent class character from the main book, whose occupation is a veterinarian.  The other investigator is Hanged Man class character from the Seven Strangers sourcebook, whose concept is something of a drifter seeking eventual retribution.  Both investigators are friends, and both have been haunted by dreams of their mutual friend Agatha in desperate trouble.  Our heroes have traveled to a little mountain town in hopes of finding her.  Things are starting to get weird, and it's delicious.  Great stuff!!!  Wonderful game!!!

That sounds like a great combo of characters!


Hello!  In regular Mork Borg, Omens can be used to neutralize a crit or a fumble.  But that bit of text is missing in Cthork Borg (other uses for Omens are the same as in regular Mork Borg).  Is leaving out neutralizing crits & fumbles intentional here in Cthork Borg?  Thanks!

Ah, this falls under rerolling a die. You can reroll crits and fumbles just as you would any other die---although if you want to rule as the GM that crits and fumbles are immune to omen'd rerolls, that's totally okay too!

The wording for 'neutralize' felt a little unclear when I was reading Mork (is a neutralized crit fail a regular fail? does it get rerolled? can more omens be spent on a neutralized roll?) so I removed the bit about neutralizing and just left the bit about rerolling dice.


Ah...I understand now...the 'neutralize' a crit or fumble is essentially already included under the 'reroll a die' provision...meaning that a player can set down an Omen and declare that the crit or fumble they just rolled is to be re-rolled (neatly side-stepping the whole 'neutralize' question).  Thank you for helping me process this information - very helpful!

No worries!

(3 edits) (+1)

Hello!  Quick rules question: can multiple Omens be spent on a single dice action?  For example, can I spend an Omen to reduce the DR of a rolled task, and if I fail the task, immediately spend another Omen to re-roll?  And if the re-roll fails, assuming I have remaining Omens, can I drop a third Omen on that same task to re-roll yet again?  In a releated vein, can a player ally spend an Omen to drop the DR of a task, and then my own character spends an Omen on a re-roll on that same task?  Can Omens pile on to a single task so that characters "can't fail" when they really need to succeed?  Or is it only "one Omen per turn" for any given task?  Thanks!

Rules as written, anyone can spend an Omen at any time to influence the dice. So you can spend multiple Omens back to back to try to pass an essential roll, and you can use an Omen to reroll a friend's failure.

You can also theoretically use Omens to influence the results of roll tables and stuff like that.

Of course, groups can absolutely change this. And individual modules can specify stuff like "you can only use one Omen per test."


This is very helpful - thank you!

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Dear Kumda1, 

Is it permissible to create and publicly share our own Cthork Borg material? 


You do still need to comply with the Mork Borg license (https://morkborg.com/license/), since Cthork is based on Mork, but their license is super permissive. Basically, there's some text you need to put on your rights page, and you can't claim to be their company, but that's the bulk of it.

For Cthork stuff specifically, if your thing is non-commercial, you can just make it, no need to ask me. If it's commercial, ask me first, but I'm not going to say no or ask for a cut unless you're like a giant corporation or something.

Also whatever it is, I'm happy to link it on this page and/or shout it out on social media.


Terrific - thank you!!!  It’s a wonderful game!


This game is so excellent.  Kumadal, have you considered working with Free League (the producers of Mork Borg and the upcoming CYBorg) to produce a hardback book like Mork Borg?  I'd LOVE to see Cthork Borg sitting on my bookshelf in a nifty little hardback alongside my Mork Borg book.  Maybe get Cthork Borg on the radar of Johan Norr and Pelle Nilsson (the Mork Borg creators), if you haven't already?  I bet they'd be thrilled to see this Lovecraftian iteration of the Mork Borg core.    And with Free League behind it, it would take Cthork Borg to a whole new level (new audience, hardback book, etc.).  I'm just so impressed with this game...what you've done here...that I want to see it go the full distance, in terms of production capabilities.  Just my two cents, and of course it's your game so it's totally up to you what happens...I'm just a fan who would love to see it get the 'full book treatment' like we see with Mork Borg.  Cheers and thanks again for such a dark gem of a game!


I've been thinking about the logistics of doing a print version, and the enthusiasm for the game definitely helps that feel more feasible!

Print version now exists!


Purchased a print copy from DriveThru!

I appreciate the support!


Hello!  Quick rules question: after investigations are completed, when a character Gets Better, if they choose to raise their Toughness by one point, do their maximum hit points also increase by one point as a result?  Or are maximum hit points tied to the Toughness score only at initial character creation? 

Rules as written, changes to Toughness don't affect max Hit Points after character creation. I also checked Mork Borg core, and it seems to be that way there as well.

That said, I'm completely okay with Toughness changes affecting max HP.

There *is* the possibility of a weird edge case where someone with very low max HP but moderate Toughness could lose a point of Toughness and hit max HP zero before they even reach negative Toughness, but I'm not sure how often that's likely to come up.


Thank you for this information…much appreciated!


Just bought. Looks amazing 

Thank you!


May I suggest a minor tweak to the Academic character class?  

On page 25, as part of the 'Academic Specialties' package...suggest making the 'Field of Study' ability +3 on Presence tests to understand information related to that field, instead of the current +2 as listed in the text.

Rationale: making 'Field of Study' a +3 ability brings it in line with the 'Well-Read' ability that all Academics receive to  decipher tomes or translate languages.  

For example, a medical doctor Academic would likely have a +3 in the field of medicine, at least equal to (not lesser than) their ability to decipher tomes or translate languages.  Similarly, an astronomer Academic would have at least the same skill rating (+3) to identify a star cluster as to decipher tomes or translate languages.

Thank you for considering!

Ah, okay. This is an interesting one, and I apologize if the system handles it a little weirdly.

The Academic should be at least a good at their profession as they are at reading.

However, gameplay-wise, Field Of Study is a broad, moderately powerful bonus and Well-Read is a strong niche bonus.

Boosting Field Of Study might make it a little too powerful, and nerfing Well-Read kind of destroys it.

My intention in making Well Read a core Specialty is that frantically reading things is usually what the academic character does in a cosmic horror game.

However, in the current build, 5 out of 6 academics don't have a Field Of Study at all. And you're right, that does feel a little weird verisimilitude-wise.

I think what I want to do is make Field Of Study a core Specialty, and make Well-Read an optional Specialty. That way every academic has a field that they're familiar with, and some are additionally really good at languages and books.

I'll spend a day or two looking this over, and I'll aim to have a patch plugged in by the end of sunday.


Yes, what you propose - making Field Of Study a core Specialty, and making Well-Read an optional Specialty  - would handle it very well!  

Perfect! I'll apply the change before the end of Sunday.

All set!


Terrific!  I love this game!


I love that this exists. Any Lovecraftian angle to the light-touch rules of Mörk Borg would be in my wheelhouse, but your spin away from strictly Lovecraft into a wider Weird Fiction mythos makes this irresistible.

For one thing nobody is going to do double takes at monster x and go “Er, is this a coded minority stereotype?” But also, the pantheon you devised would go equally well as a (almost) plug’n’play replacement for the stock deities and monsters in CoC. Captivating work!

I can’t wait to run a bunch of Cthork Borg scenarios with my group!

I'm glad you like it!

It's been a lot of fun to write and test, and I'm glad the monsters have walked that tight line between being their own thing, and being easy to drop into converted scenarios.

I hope it plays well, and if there's any kind of content you'd like added, just let me know. There's a few more small expansions in development.


Another note of appreciation for this game...reading through the Monsters and Gods...the descriptive writing is superb.  The whole game is redolent with implied setting and theme through the masterful use of language to convey the genre.  It's one of those rare game books that is a joy to read, as one can savor the words while digesting the rules and mechanical data.  No bloat, all lean and satisfying.  A feast for the imagination.  Well done!

Thank you!


Lovely to see you keep updating and expanding this wonderful thing !


Would you be able to inform what you are actually changing with your version updates ? small errors or actual small additions ?

Yep! Currently the Updates section on this page gives an overview of each change. If that doesn't feel precise enough, I can go into more detail for each item, but I was worried that would take up a lot of space on the page.

Most of the changes have been pretty minor, and the closest to a game balance problem was the former Nerve Tonic, which people could just drink all day by RAW.


Just want to cheer you on: Cthork Borg is fantastic and I'm delighted to see additional material being produced to support the line.  Bravo, sir!  And thank you for this great game!

Thank you! It's a lot of fun to write for, and I'm glad people are enjoying it!

maybe keep the updates free from ads ? like just changelogs instead of putting other works in there

All set! I've sorted the links to other Cthork stuff into a different heading.

thanks ! also nice to see so many updates , would not mind paying in the future for expansions in the form of more monsters/mechanics/items cause your stuff is as usual really good :) , do you plan to make adventures or stuff for vast grimm ? it's mork borg in space and also super cool:)


This is the first I've heard of Vast Grimm, but it sounds rad. I'll check it out.

More monsters and items are planned for Cthork Borg, although I'm aiming to do one or two more investigations first.


Will there be a print version of this for sale?

If not, do you mind if I have one made for my personal use?

I don't currently have any plans to print, although I do keep thinking about it.

Home-printed copies for personal use are totally fine. 

I'm not sure what your print process is like or if this'll be helpful information, but the PDF is layed out in 8.5 x 11 inches, 1 inch margins, .125 inch bleeds.

There is now a print version available!

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Do investigators lose Stability for seeing monsters or is it just when learning/casting magic spells?

Some monsters can inflict Stability loss, but it's not universal.

Monsters that are particularly shocking, or that exude some kind of psychic pressure, can definitely force the investigators to test against Stability loss.

However, the main use for Stability as a stat is that you can call for the investigators to test it to keep a cool head in terrifying situations. Even if a monster can't lower the investigators' Stability, you can still call for Stability tests when it's around. Investigators that fail might run, or call attention to themselves, or accidentally safety their gun/release the magazine, or otherwise make a bad judgement call due to nerves.

You can definitely do more traditional rules and have all supernatural monsters and situations cause the players to test or lose Stability, but it's optional.


This is great information - thank you!  Perhaps a line or two to this effect in the book’s section on Stability, or perhaps at the start of the monsters section.  Many veteran Cthulhu gamers are used to taking sanity losses when seeing monsters, so maybe a few words such as you have written here in response to my query would be a helpful addition to the text.  Thanks for considering!  (And great game!  Cthork Borg is fantastic!) - Brian C.


The layout's a bit precarious, but I'll squeeze an explanation into the top of the monsters section. You're absolutely right, it's a little different from the standard, and a lot of folks will expect routine san loss otherwise.

I should have a patched version up by end of day.

All set!


Great stuff!  Thanks for the edit!  What you've done is a remarkable, creative piece of work...bravo and  hats off to you, sir!  


Is this a standalone replacement or could you use this in more fantasy settings to give them a occult vibe , asking because of your new weapon additions , vehicles and classes , as this sounds cool but if all other content feels out of place compared to this then it's no good imo

It was written as a full conversion hack. I wanted to run some 1920s occult horror, so I sort of overhauled the whole ruleset.

With some adjustment, you can port any parts you like back to standard Mork Borg, but it isn't plug-and-play. There's a new attribute (Stability) which in turn affects magic, social standing, and a number of other small things.

Equipment and vehicles are probably the easiest things to convert, but they come with a new mechanic (bleed) and are more lethal than normal Mork Borg gear.

If you're looking for regular Mork Borg expansions, I do have a few of those (Bork Borg, Fisk BorgPerfidious Protoplasma) and there's mountains of cool stuff by other creators on itch.

If you're specifically looking for 1920s occult horror items/vehicles/spells for regular Mork Borg, I can write a Mork Borg expansion for that, but it'll take a couple weeks to spin up.


It's still kinda tempting just that this would be incompatible with lots of other material as it would feel out of place , might get this to run cthulhu content tho as this is probably still very minimal compared to the real cthulhu games , really interesting work you are putting out


Cthork Borg's content will definitely feel a little out of place in Mork Borg's Dying World (unless modded to add cars, firearms, etc,) but it should fit a lot of cthulhu content like a glove.


would definitely use it as a bridge ye , on the list for next pickup for sure , also fisk borg looks cool , nice work


Thank you!


You should have something analogous to The Miseries in the game to promote tension and immersion in the game world. 


Good call!

I do like the idea of the gamestate becoming more complicated as the various gods advance their objectives. I'll do some brainstorming on how to implement this, and I'll aim to get something out next week.

Miseries have been added via an expansion, Miserere Mei Deus, which is here: https://kumada1.itch.io/miserere-mei-deus

They're a little different from the Mork Borg Miseries in tone and effect, but they should provide that same sense of overarching high stakes.


Any chance of custom character sheet? :-)


I am very bad at graphic design, so I haven't tried making one yet, but I'll add it to my schedule. I should be able to have something ready by end of day tomorrow (8/25.)


Wish I had a schedule like yours!



All set!

It's got some limitations. I really do not have a background in graphic design. Let me know if there's anything that feels like it's missing.