Miskatonic Repository Additional Guidelines





General Helpful Tips

elderbullet.png  Never withhold information for dramatic effect. While players don't need to know the twist in your scenario, that information must be given early and clearly to the Keeper.

elderbullet.png  Prevent "clue bottlenecks" from occurring by tracking the progression of clues on paper once you've finished your first draft. Clues need to be available in multiple locations and obtainable by multiple means.

elderbullet.png  Keep your language clear and direct. Your text is a tool for a Keeper to use; overly poetic or technical prose can get in the way of that. Many Keepers do not read English as their first language, so jargon-free text makes your content more accessible for them as well.


Mythos Tips

elderbullet.png  Don't pin human motivations or emotions to the Cthulhu Mythos. You can reveal their goals and plans when pertinent to the plot, but in the end they are a phenomena to humanity that is alien and unknowable.

elderbullet.png  The Cthulhu Mythos isn't common. Not every fraternal society is a front for cult activity, tomes don't just lie around bookshops and libraries, most of the neighbors of Investigators are probably decent sorts. When it comes to things like spells, only give them to key NPCs who have logical reasons for having them.

elderbullet.png  Human evil is human evil. Avoid anything that would affect real-world history too much— the Mythos is not behind every historical event and people are perfectly capable of carrying out atrocities without Nyarlathotep telling them to do it. Using historical events as the backdrop to a scenario is fine and helps to place the drama.

elderbullet.png  Most Call of Cthulhu scenarios (when a monster is involved) focus on a single monster, not an assortment used to populate a "dungeon crawl".


Avoid Clichés

There are a number of tropes that have been overused in Call of Cthulhu. Although it may be possible to come up with fresh and interesting takes on them—be creative, be original. Here are some old chestnuts:

elderbullet.png  A desperate race to stop a group of cultists from performing a ritual or summoning a god.

elderbullet.png  Use of Mythos monsters as simple physical threats to be dealt with.

elderbullet.png  Problems easily resolved through violence. If the menace at the core of your scenario can be blown up or set on fire, there should be a cost to doing so or unfortunate consequences.

elderbullet.png  A group of actors is putting on a play called the King in Yellow.



The core themes of the game are horror and mystery, with a helping of difficult choices, moral confusion, and heroics in the face of insurmountable odds. Call of Cthulhu is about average people caught in a spiraling web of intrigue, doom, and terror. While the rest of humanity remains ignorant of the truth of the cosmos, a few brave and steadfast souls dare to seek out and uncover the horror at the core of existence. In this manner, the Call of Cthulhu investigator is heroic yet doomed.

While, in the main, Call of Cthulhu has a PG-13 rating in terms of violence and sexual content, dark themes can be explored and the content and tone written to fit a more mature audience. If your product for Mikatonic Repository is going to deal with mature themes, revisit our content guidelines for what limitations there are on how mature themes can be represented. Remember to flag that content early in the content itself and in the product description.


Purist or Pulp?

Be clear whether you are writing for Call of Cthulhu or Pulp Cthulhu.

Call of Cthulhu should be concerned with purist sensibilities—small victories can be won against Mythos cults and alien creatures. The investigators are fighting parts of a whole that can never be entirely defeated.

With Pulp Cthulhu, the scope is changed and reflects a more epic or cinematic ethos. Pulp Cthulhu is very action driven and fast paced. Monsters normally able to wipe out an entire party in Call of Cthulhu can face tough opposition from pulp heroes.


Racism, Sexism, and other forms of Bigotry

The 1920s and 1930s (as well as other settings) were a very different time and casual racism, sexism, and homophobia was depressingly common. While we should never shy away from acknowledging this, be careful when reflecting bigotry in your scenarios. If clumsily handled, it may be difficult to distinguish between the depiction of bigotry and actual bigotry on the part of the writer. Notes to the Keeper may help to provide context but you cannot rely on this. Try to step back from the text and imagine how the reader may interpret what you have written. Moreover, not every group will want to confront these issues at the table, and some may find them deeply uncomfortable, so ensure you flag such things early in the scenario.

Avoid stereotyping entire races. Cults are usually diverse—they’ll take anyone susceptible to their whispered promises of power. Ensure equal representation of race and gender (there’s good and bad in all communities). Cultists are not all white males and neither are the investigators.


Technical Tips

Proofread your content before putting it up on DriveThruRPG. If at all possible, ask a friend (or several friends) to help you pin down any errors. That covers grammar, spelling, punctuation, or logic errors in the scenario itself.

Common Problems: 

elderbullet.png  Passive voice: Using active voice makes your writing more direct and exciting to read. Don’t write, “The tome will be noticed on the shelf by the investigators.” Instead, try “The investigators see the tome on the shelf.”

elderbullet.png  Spacing: Use only one space, not two, between sentences. Using two spaces is a legacy from the days when manual typesetting or typewriters were the norm; with modern word processors and layout, a single space is the standard.

elderbullet.png  Numbers: For numbers "one" through "nine," spell them out. For 10 or higher, use digits instead.

elderbullet.png  Fonts: Use a font that doesn't cause eye strain to read.

elderbullet.png  Length: More is not better when it comes to length. Don't feel that you need to offer Keepers lengthy paragraphs covering hundreds of years of backstory, or multipage prose descriptions of artifacts. Keep things short and simple, allowing Keepers the time and freedom to effect their own style for a scenario. 

By using our templates, you can avoid a number of design issues, allowing you to focus more on your content.



We want to supply more art to creators in the future; your needs are likely go beyond what we're offering right now. While you can hire artists or purchase a license for art assets, there's also art and photographs that are free to use online, many of them in the public domain. These are a few directories and image search tools to get you started. Be mindful about checking the use rights, as not all the photos in these directories and search widgets will be for commercial use.


AI Content

We are concerned about the ethics of AI art and its impact on the livelihoods of artists, and the ability of artists to maintain control over use of their creations. Effective 31 March 2023, AI Art (e.g. Midjourney, Dall-E) is not permitted in new Chaosium community content titles, including the Miskatonic Repository.

Chaosium follows DriveThruRPG and Roll20 Guidelines in regards to AI Writing and Editing. Update July 19th, 2023: While we value innovation, starting on July 31st 2023, Roll20 and DriveThru Marketplaces will not accept commercial content primarily written by AI language generators. We acknowledge enforcement challenges, and trust in the goodwill of our partners to offer customers unique works based primarily on human creativity.


US Library of Congress Prints and Photograph Online Catalog


["The Sphinx, Egypt", Frank and Frances Carpenter Collection, Prints & Photographs Division, Library of Congress, LC-USZ61-797.]

The US Library of Congress's Prints and Photograph Online Catalog is vast! It contains various collections of images which could be of interest to Call of Cthulhu creators. For example, the Bain Collection features photographic files of one of America's earliest news picture agencies; the Frank and Frances Carpenter Collection showcases cultural anthropology and geography in the early years of the twentieth century; and the Historic American Buildings Survey has thousands of images from Pre-Columbian times to the twentieth century. This is just to name a few.

Images from before 1923 are considered in the public domain, as are certain images after that date. This the Library of Congress's advice about using images from its Prints and Photographs collection. You should review the status of any image you intend to use with these guidelines, and reference the source in your credits page.


The New York Public Library Digital Collections


["Crypte." The Miriam and Ira D. Wallach Division of Art, Prints and Photographs: Print Collection, The New York Public Library. The New York Public Library Digital Collections. 1882 - 1888.]

The New York Public Library Digital Collections has over three quarters of a million items featuring prints, photographs, maps, manuscripts and more. It is possible to search only the public domain materials in the collection, making it a useful and easy resource for Call of Cthulhu creators. The site also has an in-built feature enabling you to properly attribute anything you use.

The British Library on Flickr Commons


["The Ingoldsby Legends ... Second edition. (First series. With illustrations by George Cruikshank and John Leech). Ingoldsby Legends. Complete Editions. British Library"]

The British Library has released over 1 million images onto Flickr Commons for anyone to use, remix and repurpose. The images cover a diverse range of topics. The great thing about this resource is you know every item in it has no restrictions on its use!


Additional resources

elderbullet.png  New Old Stock – Vintage photos from public archives, many between 1900-1950.

elderbullet.png  creative commons search – Guides you through photographs by keyword, beta tool allows for one-click attribution information.

elderbullet.png  unsplash Photos available free, for commercial use.

You can also use Google's Advanced option on an image search to find photos by keywords and use rights.


Celebrate Joining the Repository

It's work to create a product, which is why you should celebrate finishing yours! If you're on social media, tag us to let us know about your content.









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