Eldritch Invocations of Non-Physical Intelligence

Using ChatGPT with Call of Cthulhu

I’ve been using ChatGPT for Keeper / GM prep since it was in beta, and I’ve found it really helpful. Of course, there are many different points of view and some valid concerns about artificial intelligence (AI), but today I just want to focus on using Large Language Models (LLMs) and specifically ChatGPT for improving campaigns and sessions of Call of Cthulhu.

NB: I have written this post myself, the old-fashioned way, as will probably be clear whenever my grammar gets unclear or I start rambling. Any text generated by ChatGPT will be specifically marked as such, occurring only in examples between horizontal lines (with the prompts in italics). I’m also basing the examples on the short story “Call of Cthulhu” or my own concoctions, rather than published scenarios, so as not to spoil anything. That said, if you’d like more details on any of this, let me know. All of the examples use GPT-4, the latest model used by ChatGPT. And of course, I’m still experimenting and trying to find new ways to use these tools to improve my games with friends!

Note that Chaosium is also working with Quest Portal to create Elder, the “official Call of Cthulhu AI Assistant”. At the moment, it’s trained on the core rulebooks only. I haven’t given it a spin yet, but when I inevitably do, I’ll certainly talk about it here.

Photo by Maxime VALCARCE on Unsplash

After experimenting a bit, so far the best uses I’ve found almost all revolve around preparing for the game rather than playing it solo. Here are some use cases that have worked for me. If you find them useful, let me know!

Christmas in July

Before getting started, my own scenario, The Heavenly Host, is on sale in the DriveThruRPG “Christmas in July” event. I’ve also marked down the normal price. If you’re thinking about the holidays already, or just want some weird Christmas-themed cosmic horror, maybe grab it? I just end up spending it on other independently-produced material there anyway, heh.

Handout generation

Even pre-written scenarios sometimes reference documents that are not included in the handouts: journal entries, letters, official reports, etc. ChatGPT does a great job of writing these in an appropriate style for whichever setting you’re playing in. Here are a couple of examples, including the prompts I used:

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I want you to act as an editor for a Call of Cthulhu RPG scenario. Please generate the text for a handout that consists of a rambling letter to the editor of a paper in South America, where a fanatic deduces a dire future from visions he has seen. The letter should be dated sometime in 1925 and written in English.

ChatGPT output:

The Amazon Tribune
Letters to the Editor
[Editor's Address]
[City, Country]
Dated: [Month, Day, Year]

To Whomsoever May Find Themselves Awakened to the Truth,

I pen these words with trepidation, for they come from the deepest reaches of my shattered mind, where sanity is but a fleeting wisp. My purpose in writing is not to court the attention of skeptics nor to draw the ridicule of the ignorant masses. Instead, it is to serve as a warning, a mournful wail echoing through the twisted corridors of fate.

In the suffocating embrace of the Amazonian night, I have glimpsed the dread visage of what lies ahead. The very fabric of reality seems to fray, and the malevolence that lurks beyond our comprehension unfurls its tendrils to grasp at our fragile world. How can I remain silent when the doom of humanity looms like an ominous shadow in the abyss?

A fortnight past, as I wandered amidst the primal embrace of the rainforest's depths, a feverish haze engulfed my senses. It was as though the gods themselves conspired to unravel the threads of reason that bind our existence. In that fevered delirium, I beheld visions both horrifying and mesmerizing.

I saw a colossal, cyclopean city, its spires reaching towards a bloodied firmament, crowned by an abhorrent idol of unspeakable proportions. And there, in the heart of that accursed metropolis, writhed a leviathan whose very sight threatened to corrode my soul.

The inscrutable hieroglyphs etched upon the monolithic stones seemed to foretell the awakening of a malevolent deity, an ancient entity with the power to bend reality to its will. The name "Cthulhu" resounded through my consciousness, a blasphemous whisper from a forgotten age.

As my fever abated, I found myself back in the earthly realm, drenched in a cold sweat. The madness that gripped me had granted me a revelation, a glimpse into the impending chaos that threatens to engulf us all.

But dear readers, this is no mere flight of fancy or the delusions of a fevered mind. Legends and lore, passed down through generations, lend credence to the horrors I have seen. I urge you, do not dismiss these forebodings as mere superstition.

Heed this warning! The stars align, and the barriers weaken with each passing day. The impending catastrophe draws near, and we teeter on the precipice of an apocalyptic cataclysm. The vile machinations of cosmic entities conspire to render our world a charnel house of despair.

I implore the learned minds of our esteemed publication and the public at large to heed the signs and prepare for the dark days ahead. The ancient texts must be studied, and the secrets of forgotten cults must be unveiled. Only through knowledge can we hope to confront the unfathomable malevolence that lies dormant in the eons-old depths.

May this desperate plea find open minds and willing hearts, for time is fleeting, and the tendrils of cosmic dread inch ever closer to our reality. I pray that this letter serves as a beacon of warning amidst the encroaching darkness.

In dread and hope,
[Your Fictional Character's Name]
A Seeker of Forbidden Truths

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That one might be a little straightforward as the prompt came almost directly from Lovecraft’s own story. I followed up in the same thread with the following:

Now generate a police report for the New Orleans Police Department describing the arrests of multiple individuals for disturbing the peace and possession of human remains. The report should describe a ritual in which multiple people were engaged in some sort of religious ritual centered on a statue with a bowl of blood of indeterminate origin in front of it. The report should reflect official language and be written in a style appropriate for 1925.

ChatGPT output:

[Official Police Report - New Orleans Police Department]

Case Number: 1925-XXXXX
Date: [Month, Day, Year]
Reporting Officer: [Officer's Name and Badge Number]
Incident Type: Disturbing the Peace, Possession of Human Remains

On this [Date], at approximately [Time], the New Orleans Police Department responded to a report of a disturbance at [Address of Incident], within the jurisdiction of [Police Precinct Name]. Upon arrival, officers observed a gathering of multiple individuals engaged in what appeared to be a religious ritual within a private residence.

The reporting officers approached the premises with caution, as sounds of chanting and unusual incantations emanated from within. The group's actions were perceived as alarming to the neighbors, prompting them to report the matter to the authorities.

Upon entry into the residence, officers were confronted with a scene that defied rational explanation. A total of [Number of Individuals] individuals, dressed in garbs reminiscent of arcane rituals, were huddled around a central statue, standing approximately [Height] tall, and adorned with esoteric symbols and markings. The statue was situated upon an altar-like structure, bearing a bowl filled with what appeared to be blood of indeterminate origin.

The participants, who were fervently chanting and swaying in unison, seemed wholly consumed by the intensity of the ritual. Their actions conveyed a sense of religious ecstasy, which only deepened the concern for public safety and peace.

During the apprehension of the involved parties, officers discovered the possession of human remains within the vicinity of the ritual site. The remains consisted of a collection of bones and skulls, their exact origin yet to be ascertained, but clearly indicative of the use of mortal remains in this ceremony.

The arrested individuals exhibited resistance during the arrest, but with the assistance of backup officers, they were successfully apprehended and brought into custody. All individuals were identified as follows:

1. [Suspect 1's Name] - [Age] years old, [Physical Description]
2. [Suspect 2's Name] - [Age] years old, [Physical Description]
3. [Suspect 3's Name] - [Age] years old, [Physical Description]

[Include additional suspects as applicable]

The seized items from the scene include the aforementioned statue, the bowl of blood, the human remains, and various ritualistic paraphernalia, which shall be held as evidence pending further investigation.

Medical personnel were called to the scene to evaluate the condition of the arrested individuals, as they displayed signs of potential exposure to dangerous substances or psychological distress resulting from their participation in the ritual.

In accordance with the laws of the state of Louisiana, all suspects will be charged with Disturbing the Peace and Possession of Human Remains for purposes of furthering a religious ritual. They shall be held in custody at [Name of Detention Facility] until their arraignment before the appropriate court.

This report is filed in compliance with departmental guidelines and for record-keeping purposes. Further investigations into the origins and nature of the ritual, as well as the possible involvement of any clandestine or cultic activities, will be pursued under the direction of [Name of Investigating Officer].

Respectfully submitted,

[Officer's Signature]
[Officer's Name - Typed]
[Badge Number]
[Rank/Designation]
[Date and Time of Report Filing]

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In a follow-up, I asked it: Please fill in the details in that report, generating dates, times, names, and suspect details as needed for the fiction. These should all be fictional and not refer to actual persons. Repeating all that here would be, well, repetitive, but it did a good enough job, along the lines of what you might expect from any random name generator and the like.

Related to this, you can ask for a vivid description in Lovecraftian style suitable to read aloud to players, if that’s the sort of thing your group enjoys. Give it a few words about an underground temple to Cthulhu or a brief description of a cult leader and it will give you the purplest of prose. Spell descriptions (particularly in-world texts about how to carry out a spell) are another great use case here.

Text Summary

Whether from an old Call of Cthulhu scenario or some other research source, sometimes a piece of text can be extremely long or written in a relatively impenetrable style. ChatGPT does a good job breaking that down, whether into a prose summary or bullet points.

However, this only goes so far as ChatGPT has limitations on how much text you can submit at once. My advice here is to summarize sections at a time. For example, a scenario might have sections on Keeper’s Information, specific significant NPCs or locations, and key scenes. It can summarize each of these. From there, I like to copy the bullet points into a local document or note so that I have the summaries to hand during a session.

Obviously, this has applications far beyond tabletop gaming, but even then that can lead to overlap. Our hobby has a bit of notoriety for the research rabbit holes we go down when trying to prepare a session or write a scenario. Whether you want a brief summary of the history of a particular location or a technology, ChatGPT can do a decent job. Here’s an example:

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I want you to act as a history expert focused on the 20th-century United States. Please give me a brief summary of the state of New Orleans in the 1920s.

ChatGPT output:

Sure, I'd be happy to provide a brief summary of New Orleans in the 1920s.

The 1920s, often referred to as the "Roaring Twenties," was a time of significant change and development in the United States, and New Orleans was no exception. This period followed the end of World War I and was characterized by economic growth, cultural shifts, and technological advances.

New Orleans, with its strategic location at the mouth of the Mississippi River, was an important hub for trade and transportation. Its economy relied heavily on shipping, oil, and the burgeoning tourism industry, as well as agriculture, particularly sugar and cotton.

The city's rich cultural heritage continued to evolve during this period. The 1920s was the Jazz Age, and New Orleans, as the birthplace of jazz, was at the center of this cultural revolution. Jazz music, born from a blend of African, Caribbean, and European musical traditions, reached new levels of popularity and artistic sophistication. Influential musicians such as Louis Armstrong, Jelly Roll Morton, and King Oliver were active during this period and brought New Orleans-style jazz to a national audience.

The African American community of New Orleans contributed significantly to the city's cultural development. Despite the racial segregation and systemic racism of the era, Black New Orleanians created vibrant communities and institutions, and their contributions to music, food, and other aspects of culture were profound.

The city was also known for its distinctive Creole culture, which is a mix of French, Spanish, African, and Native American influences. This can be seen in the city's unique architecture, food, music, and dialect.

In terms of governance and politics, New Orleans, like much of the South, was dominated by the Democratic Party. This period saw a continuation of the political machine-style governance, with a network of politicians, business owners, and community leaders wielding considerable influence.

In summary, New Orleans in the 1920s was a city of cultural innovation and economic growth, but also a city grappling with the realities of racial segregation and political corruption.

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Don’t rely on ChatGPT for actual research for school, work, or anything else where accuracy matters, as it has a tendency to invent “alternate facts” that sound true but aren’t! For RPG purposes, though, that’s usually good enough.

Campaign Structure

One of my favorite ways to play Call of Cthulhu is to take existing standalone scenarios and link them into a single, cohesive campaign. I’ll look for scenarios that share some common element or theme and alter them as necessary. That generally means moving the locations around, changing NPCs so that some of the same ones recur, and inserting clues whose importance becomes clear in later parts of the campaign.

ChatGPT helps me generate those links sometimes. I’ll feed it a list of scenarios with a very brief synopsis and a few constraints, like noting the region where I want the campaign to occur or excluding certain elements. For example, I gave it some scenarios that could all fit in the American Southwest (even if the original text has them elsewhere) and note that I do not want to emphasize Native American beliefs and mythology for reasons of cultural sensitivity. (Claiming that the beliefs of oppressed people who’ve undergone genocide by my own settler ancestors are actually cover for the worship of evil gods seems insensitive at best. That’s a topic for another time, though.)

The result is a set of suggestions of where NPCs could be linked together. In the example described in the previous paragraph, I suggested the following scenarios with extremely brief synopses (omitted here for obvious spoiler reasons):

1. The Secret of Castronegro (from Cthulhu Companion)

2. Devil’s Canyon (from Shadows of Yog-Sothoth)

3. The Darkness Beneath the Hill (from Doors to Darkness)

4. Pilgrim’s Hope (a Miskatonic Repository scenario)

5. Black Devil Mountain (from The Asylum and Other Tales in the Classic Boxed Set)

These scenarios come from a range of sources and time periods (in terms of the development of the game). ChatGPT gave me three suggestions for campaigns using these. One used a recurring monster type, including changing a few of the scenarios to focus on that monster type. Another suggested using the villains from one scenario as the central villains for the whole campaign, with specific ways of having them pull the strings for the various monsters and villains in the other scenarios before building to a climax. The final campaign outline tied all the scenarios together into a grand plot to summon the Great Old Ones to Earth, again suggesting one in particular as a good candidate for the climax and ways that I could foreshadow this overarching conspiracy throughout all of them!

I also asked it to focus the campaign more on the occult rather than the Lovecraftian Mythos. It did an excellent job reframing the campaign on traditional horrors (vampires, witches, etc.). Then I asked it again to go back and use a particular Mythos deity as the central theme for a campaign with those scenarios. A few of them became a bit of a reach, but in all honesty that’s because tying those scenarios to a an unrelated deity required that.

Rules Clarifications

While perhaps not as robust as the above-described Elder, ChatGPT does decently well at explaining some of the more arcane bits of Call of Cthulhu 7th Edition. Here are two examples:

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Please explain the rules for automatic weapons in Call of Cthulhu 7th Edition.

ChatGPT output:

The rules for automatic weapons in Call of Cthulhu 7th Edition are designed to reflect the potentially massive amount of damage these weapons can do, while also considering the difficulty of controlling such weapons. Here's a breakdown:

1. Regular Attack: A regular attack with an automatic weapon simply means firing a single shot as if it were a non-automatic firearm. It uses the character's standard Firearms skill and damage for the weapon.

2. Burst Fire: This represents firing a short burst of rounds at a single target. This gives you a bonus die on your attack roll (meaning you roll an extra tens place die and take the better of the two). If successful, it hits a number of times equal to the number of bullets in the burst or the number you roll on the D10, whichever is lower.

3. Full Auto: This is the most drastic use of an automatic weapon, representing spraying a zone with bullets. You decide how many bullets to fire (up to the weapon's maximum) and distribute the attacks among targets as you see fit. The maximum number of targets is equal to the number of tens of bullets fired (so, for example, if you fired 30 bullets, you could target up to 3 different creatures). Each individual attack roll has a penalty die (you roll an extra tens die and take the worst result), but each successful hit inflicts full damage.

4. Ammo and Reloads: Automatic weapons can go through ammunition quickly. Keeping track of ammo and reload times is crucial. Most automatic weapons need a full round to reload.

Remember, automatic weapons are loud and may attract unwanted attention. Also, in a typical Call of Cthulhu setting, they might not be readily available or legal to possess, which can lead to complications for investigators. It's up to the Keeper to determine how these factors come into play.

It's important to note that these rules can be subject to changes or adaptations by the Keeper, based on their interpretation or to better fit their campaign's narrative and style. Please always refer to the latest rulebooks or your Keeper for the most accurate and up-to-date information.

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I also had a longer chat with it about recovering Sanity points in the game, including asking it to go into more detail on points I had doubts about:

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Can you summarize the rules for the Investigator Development Phase in CoC 7th Edition?

ChatGPT output:

Sure, the Investigator Development Phase is an important part of Call of Cthulhu 7th Edition as it allows investigators (characters) to improve their skills based on their experiences during the game. Here's a simplified summary of the rules:

1. Determine Skills Used: At the end of a scenario or campaign chapter, the Keeper (Game Master) will usually call for an "Investigator Development Phase". This is the time for each player to review their character sheet and check which skills they've used successfully during the course of the adventure. These skills should be marked with a check (√) during gameplay to indicate they've been successfully used.

2. Skill Improvement Rolls: For each checked skill, players roll percentile dice (d100). The goal here is to roll over their current skill value. If they succeed in rolling over their current skill value, it means their investigator learns from their experiences and they improve that skill.

3. Improvement Value: For each successful improvement roll, players then roll a d10 and add the result to the current skill value. This represents the investigator becoming better with that skill through practice and application.

4. Reset Checks: After the improvement rolls are made, all check marks should be erased, ready for new checks in the next scenario.

5. Hit Points and Sanity: Investigators recover hit points and sanity points as well during this phase. Hit points recover at a rate determined by the Keeper based on how much time passes, and sanity points can be restored through psychotherapy or rest, again, depending on the time elapsed and Keeper's decision.

6. Advancement: Investigators can also learn new skills or improve current ones by studying books, training, or being taught by others. The Keeper sets the difficulty level and time required for this learning process.

Remember, the Investigator Development Phase is also a good opportunity for players and the Keeper to role-play downtime activities and reflect on the events of the previous game, which can help build character depth and drive the narrative forward.

Please give more detail about recovering Sanity points during this phase.

ChatGPT output:

Sanity recovery in Call of Cthulhu 7th Edition can be a bit complex because it depends on several factors. During the Investigator Development Phase, Sanity points may be restored through several means:

1. Rest and Recuperation: If an investigator has not lost any Sanity points due to encountering a Mythos creature or experiencing a bout of madness in game time that has just passed, the Keeper might allow them to regain 1D6 Sanity points to reflect the restorative effects of simple rest and normal life.

2. Psychotherapy: If the investigator is undergoing psychotherapy, a successful Psychoanalysis roll made on their behalf by a therapist once per month allows for the recovery of 1D3 Sanity points.

3. Self-Help: Investigators confined to a mental institution can try to recover sanity on their own. This requires a successful Psychoanalysis roll, and if successful, they recover 1 Sanity point.

4. Successful Completion of an Adventure: At the end of a successfully completed scenario, investigators may gain Sanity points for overcoming the horrors of the Mythos and for stopping whatever terrible events were in motion. The exact amount of Sanity points regained is usually listed in the scenario.

5. Defeating a Mythos Entity: If investigators defeat a significant Mythos entity, they may recover Sanity points. The amount regained is usually equal to the creature's Sanity loss die or dice, and should be listed in the creature's statistics or described in the scenario.

6. Mythos Tomes: Certain Mythos tomes might restore Sanity points once fully read and understood. However, this often comes with an increase in Cthulhu Mythos skill, which reduces the investigator's maximum possible Sanity.

7. Learning a New Spell or Increasing Cthulhu Mythos Skill: Both of these usually decrease an investigator's Sanity, reflecting their growing awareness of the terrifying reality behind the veneer of normal life.

Remember, Sanity recovery is up to the Keeper's discretion and the specifics of your game's scenario or campaign. Also, recovery of Sanity points can never increase an investigator's Sanity above their starting Sanity or above their current maximum possible Sanity, which is equal to (99 - Cthulhu Mythos skill).

Is there a method for recovering Sanity points based on spending time with an investigator's backstory elements?

ChatGPT output:

Yes, absolutely. A key element of the Call of Cthulhu 7th Edition rules is the inclusion of personal backstory elements, known as "Backstory Connections," which can aid in Sanity recovery. This system recognizes that spending time with significant people, places, or things that hold emotional value can provide psychological comfort and stability.

Spending Time with a Key Connection: During the Investigator Development Phase, if an investigator spends a significant amount of time (usually a week or more) with their chosen key connection - a person, place, or treasured possession that is part of their backstory - they can potentially regain Sanity points.

The Keeper might ask for a Sanity roll. If the roll succeeds (the result is under their current Sanity), the investigator finds solace and comfort, restoring 1D6 Sanity points. If the roll fails (the result is above their current Sanity), the situation is more fraught, complicated, or somehow not as comforting as it could be, and no Sanity points are regained.

However, the Keeper might decide that no roll is needed and automatically award 1D6 Sanity points for spending time with the key connection.

Do note that this form of recovery can only be used once per game month and it is up to the Keeper's discretion to allow it. This rule encourages the role-playing of the investigators' personal lives and relationships, providing more depth to the characters and potentially interesting narrative hooks for the Keeper to exploit in the game.

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I don’t know that every detail of the above is entirely correct in terms of the strict text of the game, such as the idea that Mythos tomes can restore Sanity. But as a general source, this works pretty well. And frankly I don’t understand the automatic weapon rules well enough to determine how correct the summary was, but it seems close at least.

A note on safety

OpenAI has implemented guard rails in an attempt to prevent their tool from being used for purposes they find inappropriate. Call of Cthulhu RPG content may occasionally violate their usage policy. Relevant prohibitions include:

• Content that expresses, incites, or promotes hate based on identity

• Content that promotes or glorifies violence or celebrates the suffering or humiliation of others

• Content that promotes, encourages, or depicts acts of self-harm, such as suicide, cutting, and eating disorders

Generally, I’ve found that doing things like specifying that I don’t want it to describe something in graphic detail or that I would like to modify something so that it doesn’t reference real-world cultures in offensive ways has worked. And noting in particular that the text is for use in the Call of Cthulhu RPG (or for a roleplaying game in general) seems to satisfy it preemptively in almost all cases, although it may include some disclaimers or warnings within the text itself. Once it even reminded me to “Remember, this spell is only for use in the Call of Cthulhu RPG and should not be used to harm someone in real life”.

If you enjoyed this and think somebody else might find it useful, consider sending it to them!