Category Archives: Open Cthulhu

The Open Mythos … Downloadable SRD

We must confess we have been a little overwhelmed by all the positive support that’s been directed at our free/open collection of Cthulhu Mythos entities, rituals, artifacts … all derived from 100% public domain works by Lovecraft.

In fact we have received only one criticism about the Open Mythos — many people want to have it as a downloadable resource. Sounds like a great idea to us … and hence was born the “Open Cthulhu Mythos SRD”, a compilation of all the stats and descriptions that were Lovecraft-inspired.

The SRD was released today and it’s a Pay-What-You-Want title on DriveThruRPG.

While this version is text only, don’t forget that the Mythos illustrations and other artwork on the Cthulhu Eternal website is also published under an open license (in particular a Creative Commons license), so you are more than welcome to reuse any of those pieces as long as you credit the original illustrator.

We hope that by making game stats freely available for a wealth of Lovecraft creations we can provide a platform on which other creative folks (and I’m sure you’re one of them!) can make awesome new scenarios/campaigns/games.

The Open Mythos: A Free/Open Resource for TTRPGs

Today is an exciting day … especially if you are a creative game designer who has ever dreamed of unleashing your original Lovecraftian scenarios, campaigns, or freaky new TTRPG settings.

Why? Because today we are thrilled to be announcing the completion of a collaborative project we have been running with our excellent friends at the German Lovecraft Society … an initiative to create a truly free and open set of game statistics for all of the unique horrors invented by H.P. Lovecraft and used to dreadful effect in his stories.

We are calling this collection of game elements the “Open Mythos”. It is available right now online at: … and is published under an open license, meaning the full text (and artwork) is re-usable by anyone, either for personal or commercial purposes (as long as the terms of the licenses are met).

The Open Mythos covers five major areas: Lovecraftian Entities (gods and monsters), Unnatural Rituals, Terrible Tomes, Strange Artifacts, and organized Mythos-related Cults. The entries in the Open Mythos have been scrupulously researched in order to ensure that they are purely derived from Lovecraft, and more particularly from Lovecraft stories that are universally recognized as being in the public domain. A major objective of ours was to create a Mythos corpus that is reliably free of the kinds of “licensing complications” that plague other similar bestiaries and game books which have draw upon a broad selection of Cthulhu Mythos fiction, including stories which are still under copyright.

The Open Mythos game descriptions are written to be compatible with the rules engine we have built for both the Cthulhu Eternal RPG and it’s twisted post-Apocalyptic sibling APOCTHULHU. These systems are also highly compatible with the FHTAGN roleplaying game released by the Deutsche Lovecraft Gesellschaft. In theory you could also use these game statistics for other D100 games with a minimum of tweaking.

A principal motivation shared by both ourselves and the German Lovecraft Society is the creation of a set of game resources that everyone in the Lovecraftian TTRPG community can use for free, to add creative fuel to the flames of your imagination. From speaking with many gamers, one of the most commonly cited barriers to self-publishing original game creations is the hurdle of having to either license or build-from-scratch an entire Lovecraft-fuelled game world, complete with game stats for everything. With the release of the Open Mythos we hope we have lowered the bar for indie publishers to get their unique new ideas out into the marketplace, and into the hands of gamers around the world.

For those who are curious about the details of what is in the Open Mythos write-ups, here’s a quick summary. The full gory details can be obtained via the link above.

  • 40 Lovecraftian Entities: Azathoth, Beings of Ib, Bholes, Bokrug, Cats of the Dreamlands, Colour Out Of Space, Cthulhu, Creeping Corpses, Dagon & Hydra, Deep Ones, Elder Things, Formless Hunter, Ghasts, Ghouls, Gnorri, God of the Sunken Temple, Great Race of Yith, Gugs, Hounds of Death, Hypnos, Keziah Mason, King in Yellow, Leng Folk, Mi-Go, Moon Beasts, Night-gaunts, Nodens, Nyarlathotep, Polyp Horrors, Rat Things, Resurrected Abominations, Resurrected Corpses, Shantaks, Shoggoths, Shub-Niggurath, Spiders From Leng, Star Spawn, Winged Servant, Yog-Sothoth, Zoogs
  • 21 Unnatural Rituals: Accelerated Healing, Aklo Sabaoth, Annihilation, Banish Entity, Body Swap, DHO-HNA Formula, Dominate Will, Elder Sign, Elixir of Life, Erase Memories, Essential Saltes, Forge Ancestral Bond, Inflict Harm, Music of the Spheres, Open Dimensional Rift, Powder of Ibn-Ghazi, Prolong Life, See Through The Ages, Sign of Koth, Summon Entities, Voorish Sign
  • 14 Terrible Tomes: Azathoth and Other Horrors, Book of Azathoth, Book of Dzyan, Brick Cylinders of Kadatheron, CTHULHU CULT (Angell’s Files), Daemonolatreia Libri III, Ilarnek Papyri, The King in Yellow (play), Liber Damnatus Damnationum, The Nameless Book, The Necronomicon, Pnakotic Manuscripts, Scientific Notes of Dr. Herbert West, Seven Cryptical Books of Hsan.
  • 8 Strange Artifacts: Cthulhu Idol, Golden Tiaras of the Deep Ones, Great Race Mental Projection Apparatus, Jade Soul-Amulet, Mi-Go Brain Cylinder, Mi-Go Communication Implant, The Shining Trapezohedron, The Silver Key
  • 8 Mythos-related Cults: Cannibal Cult of Leng, The Cthulhu Cult, Cult of the Wise Ones, Cult of the Worm, Esoteric Order of Dagon, Shepherds of Hastur, Starry Wisdom Sect, Witches Covens

With all this free and fully-open game content at your fingertips (or pseudopods, we’re not ones to judge), there is no end to the horror that can be unleashed upon the gaming world.

And that’s a great thing!

The Victorian Apo-Hack

Welcome to another year — we’re looking forward to something new and (eventually) better from 2021, and we sincerely hope that’s true for you also.

Back in December we released the APOCTHULHU SRD — the barebones version of our full RPG engine that’s absolutely open and free for anyone to use (for personal or commercial projects). Ever since we did that we have been getting a steady stream of folks downloading the SRD, but also a steady stream of questions about the SRD.

The most frequent thing people ask about the SRD is … “so, can I use this to make game content that has nothing to do with Post-Apocalyptic stuff?” The simple answer to that is, “of course you can!” Open means OPEN; if you can find some way to recycle the rules of our game to make something completely new and original and unrelated to Apocalyptic worlds, you absolutely can. Not only that, we would LOVE for you to build your new content based on the skeleton of our game, and as per the terms of the OGL you don’t need to pay us a cent in licensing (as long as you follow the attribution and other rules in the OGL contract).

These various questions about recycling APOCTHULHU’s core system got us to thinking, though … what could WE do with that same rules engine. When designing the game — based upon other pre-existing OGL rulesystems, we might add — we looked to make something as flexible as possible. After all, APOCTHULHU is supposed to be able to power any number of different “end of the world” scenarios so it can’t be terribly specific to any one setting.

We realized when combing through the rules subsystems in our SRD, there are really only 4 areas that need to be tweaked to adapt the rules to an entirely new Lovecraftian setting. These are:

  1. Harshness: what types of environmental backgrounds in the new setting (if any) might be considered so awful that someone growing up there might be stronger-but-mentally-scarred? This is what APOCTHULHU’s Harshness ratings are all about. An auxiliary question is: if there are Harsh backgrounds, what types of “Adversity Skills” might someone be given to recognize the challenges they’ve needed to overcome to become a player-character adult
  2. Skills: The APOCTHULHU skills list is sort-of generic in lots of ways, but if you’re targetting a historical era or somewhere far in the future, they’ll need a bit of tweaking in some places
  3. Archetypes: Similarly, the set of character templates in the APOCTHULHU SRD are geared towards Post-Apocalyptic games; for other settings you’d need to devise some new archetypes particular to the time/place
  4. Equipment-related: Weapons and Vehicles available at different historical periods vary a lot. The generic list of both in the APOCTHULHU SRD are a good cross-section of possibilities, but for other settings you’d probably want to build more specific tables of both.

And that’s about ALL that needs tweaking to make a brand new flavour of Lovecraftian gaming — well, from a rules perspective anyway. To make a fully evocative setting you’d need to write a lot of flavour text to spark ideas in both players in GMs, but that’s a whole different type of RPG development.

As an experiment to validate the above, we decided we would see how easy it would be to hack the APOCTHULHU SRD to build the core mechanics for a Pre-Apocalyptic game set somewhere in the Victorian Age of history. That’s basically 1850s through to 1900. So, the kind of Jack the Ripper and Sherlock Holmes kind of era.

Based on the above we devised a Victorian-Age variant of the APOCTHULHU Skills List and using that built 11 typical character archetypes for the era. We also put together some tables of weapons and vehicles common in the era.

You can download the PDF hack-notes here:

SRD HACK – Victorian Age Cthulhu

(it should go without saying that for this to be useful to you, you’ll also need the APOCTHULHU SRD file. Thankfully you can get this for free via this link or from DriveThruRPG if you’d prefer).

In the spirit of collaborative invention, we thought we’d share the results of our experimental hacking — if this material is helpful to you, feel free to use it however you want! If this kind of thing is especially helpful to other designers or game-hackers, we’ll create some more for other historical eras … drop a comment below if you have any ideas about cool settings that you’d think are crying out for a Lovecraftian treatment.

Open Cthulhu: “Satan” or “Saviour”?

Or, An Investigation into the Provenance of the “Open Cthulhu SRD”

One of the most controversial things to happen this year in the world of Lovecraftian tabletop RPGs has been the (non-)release of the Open Cthulhu SRD and the subsequent debate about its alleged Intellectual Property infringements.

I don’t think there’s any value in rehashing the lengthy (and generally insightful) debate that transpired on the Yog-Sothoth Forum (you must sign-up for free forum membership to see this content). But as a brief capsule summary anyway:

  1. A group of (AFAIK) unknown game designers created a d100 game of Lovecraftian horror which they aimed to release under the OGL; they posted links to their file on YSDC and other forums.
  2. Moon Design (Chaosium) promptly contacted both the creators AND the sites which hosted this link and bluntly asserted this material was in breech of their Intellectual Property and also that of various Cthulhu Mythos fiction authors. Moon also asserted that Open Cthulhu’s use of material from Mongoose Publishing’s OGL version of Runequest was also illegal since that latter work’s OGL was no longer valid.
  3. The Open Cthulhu group re-worked their SRD and claimed to have removed all the references to Mythos creations by any authors other than Lovecraft (whose solo works are now indisputably in the Public Domain) and replaced all content drawn from the Mongoose Renaissance OGL with material from the Legend RPG (which is 100% OGL).
  4. Lively debate followed about trademarks, the nature of the OGL, and other topics concerning Intellectual Property; Moon Design also asserted that they had re-assessed the revised Open Cthulhu SRD and found it to still be in breach of their IP (without citing specifics).

One of the things that I have observed about the online debate about Open Cthulhu is that most of the comments made about it’s use of the OGL are, to some extent, hypothetical (including my own).There are plenty of opinions which are qualified along the lines of “If Open Cthulhu’s claims are true about it being derived from valid OGL content then …” or “If Open Cthulhu has copy/pasted text from Chaosium publications then …” The reason these are hypothetical is because nobody has (to my knowledge) gone through the Open Cthulhu SRD with a fine-toothed comb to try to unpick its provenance. That is, to unravel the DNA of this controversial newborn? (stillborn?) beast.

So, I decided I would sit down and do just that — opening up the latest Open Cthulhu SRD side-by-side with all of the OGL documents it claims as its ancestors AND copies of multiple editions of Chaosium’s Call of Cthulhu rules (specifically 4th, 5th, and 6th editions).

The analysis took me a LOT longer than I thought — several days of concerted effort — but at the end of it I have gained a fair degree of understanding of what this beast is, and where it’s various parts seem to have come from. In this post I’ll summarize some of those findings.

Quick Summary (or TL;DR)

  1. Open Cthulhu’s claim that it contains no references to non-Lovecraft Mythos elements is basically justified
  2. The OGL ancestry of Open Cthulhu, as stated in its own OGL License seems legitimate
    • Open Cthulhu draws in text from the Delta Green Agent’s Handbook (approx 16% of the Open Cthulhu wordcount), the Legend RPG (2% of the OC wordcount), Eldritch Tales and the Cthulhoid Bestiary for OSR (together 6% of the OC wordcount). Plus it has a smattering of text drawn from the Delta Green Quickstart
  3. While a significant part of the Open Cthulhu text comes from pre-existing OGL rules, two-thirds of its text is apparently new content.
  4. Some of the apparently new content represents rules/content that have no relationship at all with Call of Cthulhu (or any other Chaosium book I’m familiar with); however other pieces look like they are clearly intended to be “retro-clones” of pieces of older Call of Cthulhu editions.
    • In terms of wordcount, about 31% of Open Cthulhu SRD appears to have a “Chaosium influence,” versus 35% of the SRD text which is new content but not inspired by Chaosium’s rules (as far as I can tell)
  5. Looking very closely at the Chaosium-influenced parts of the Open Cthulhu there is no evidence I could find of a direct “copy/paste” anywhere but plenty of examples where similar rules have been re-written using different words


In order to analyze the provenance of different pieces of the Open Cthulhu SRD I decided to create a version of the OC text in a form that allowed me to “colour-code” different sections of text based on provenance. That is, whether it was directly (or almost-directly) copied from an OGL source, whether it was a wholly-original creation, or whether it was new wording attempting to reverse-engineer parallel text from Call of Cthulhu.

In the end my categorization scheme grew to recognize:

  • Five OGL “flavours”: Delta Green Agent’s Handbook, Delta Green Quickstart, Adaptations of Delta Green rules, Legend RPG, and Miscellaneous OGL material (covering Eldritch Tales and the Cthulhoid Bestiary)
  • Two Categories of original material: Entirely Original, Chaosium-influenced
  • Two Miscellaneous categories: H.P. Lovecraft Quotations, OGL License Text

Categorizing (colour-coding) the different sections of the Open Cthulhu SRD was undertaken by comparing the relevant rules/resources text side-by-side with each of the relevant OGL sources and then against the different editions of the Call of Cthulhu rules. Where no source had any clear resemblance to any of those sources I assumed it to be original to Open Cthulhu.

Once each word of the Open Cthulhu SRD had been allocated into one of the categories, statistics were gathered of the total number of words that had been assigned to each category and the proportion they represent of the total Open Cthulhu wordcount.

For a full table of raw data in PDF form, click here.

The Structure of the Open Cthulhu SRD

The Open Cthulhu SRD is structured as shown in the diagram below, being split into two main sections — a Rules Section (aka the Player section) and a Keeper Section.

Overall the Open Cthulhu SRD consists of 61,014 words.

In terms of wordcount, the rules make up about 40% of the total file, with the Keeper section making up the bulk of the rest. There’s a small amount of intro and outro material at the front and back of the file respectively; the outro is made up of the OGL license text.

Overall Observations and Analyses

Looking at the Open Cthulhu SRD in its entirety, the breakdown of words assigned into each of the nine categories is as follows:

OGL Categories

Content from Delta Green Agent’s Handbook: 9,520 words (15.6%)
Content from Delta Green Quickstart: 270 words (0.4%)
Content extrapolated/adapted from Delta Green Agent’s Handbook: 2,978 words (4.9%)


Content from Legend RPG: 1,368 words (2.2%)
Content from Miscellaneous OGL sources: 3,837 words (6.3%)

Original Content Catgories

Entirely Original Content: 21299 words (34.9%)
Chaosium-inspired Content: 19052 words (31.2%)

Miscellaneous Categories

H.P. Lovecraft Quotations: 1736 words (2.8%)
OGL License Text: 954 words (1.6%)

Use of OGL Material

It is clear that large sections of the Open Cthulhu rules section — especially the combat and sanity rules — are copied directly from OGL content in Delta Green. In some cases this material has been edited down to simplify rules or to omit particular parts altogether. For example, Open Cthulhu does not make use of the Character Bonds mechanic at all and all references to it have been edited out. Similarly, the combat rules in Open Cthulhu simplify some of the ways in which high-tech weaponry and/or militaristic weapons are represented.

On the other hand, there are places in Open Cthulhu where the core concepts introduced in Delta Green have been adapted or extrapolated. These are mostly minor, for example the renaming of DG’s “combat turn” to OC’s “combat round” or the expanded set of descriptions for how Lethal Damage affects different types of Mythos creatures.

Leaving aside Delta Green, it is clear that Open Cthulhu’s use of other OGL sources is more slight than might otherwise be assumed. In particular its direct inheritance from the Legend RPG is really very small and is mostly concerning game stats and character creation. The material which is sourced from Eldritch Tales is mostly short descriptions of different Great Old Ones, Mythos Creatures, and Eldritch Artifacts. Open Cthulhu’s borrowing from the Cthuloid Bestiary for OSR is similar, albeit on a much smaller scale — it draws upon descriptions of several Mythos monsters that are not mentioned in Eldritch Tales.

Original vs Chaosium-Inspired

As noted above despite its reliance on OGL sources for the bulk of its rules, more than two-thirds of the words in the Open Cthulhu SRD would seem to be new content (i.e., not derived from an OGL source). One of the more difficult aspects of this analysis was trying to separate out which parts of these non-OGL-derived sections represent entirely original ideas and which are intended to be similar-but-not-identical versions of rules from Chaosium’s Call of Cthulhu game.

It is very clear that both types of text appear in the Open Cthulhu SRD.

As evidence of entirely original content, I would point at things like Open Cthulhu’s rather intriguing new take on game stats for Great Old Ones (which it terms “Mythos Powers”). Rather than giving these entities full game stats, as Call of Cthulhu does, OC characterizes them more by the perils of mental contact and the raw Lethality of their physical forms (as a single game stat). Another idea that is (to the best of my knowledge) original to Open Cthulhu is the concept of Investigators needing to make a roll to become “immersed” in a Mythos Tome (i.e., truly believe it isn’t gobbledygook) before they can research its contents.

On the other hand, it is equally clear that there are many cases where Open Cthulhu has introduced rules which are obviously inspired by Call of Cthulhu. Examples which come to mind include the specific skills breakdown in Open Cthulhu which, while not a complete copy of the skills list in early Call of Cthulhu, preserves some of the quirkiness of those editions’ characterization of Investigator knowledge. Another clear example is the inclusion of a brief set of game rules for running Dreamlands adventures which seems closely analogous to rules in Chaosium’s H.P. Lovecrafts Dreamlands (and latter editions of the CoC rules).

A Breach of Copyright?

One thing that is very clear upon a close reading of the Open Cthulhu SRD is that it definitely *is* aiming to be a “retro clone” of pre-7th Edition Call of Cthulhu, in the sense that its rules are similar enough that they could be used to play supplements released for those editions. Arguably, given the slow and slight way in which rules change between different editions of Call of Cthulhu, this also means one could (without too much work) use the Open Cthulhu SRD rules to run more recently-published scenarios as well (which would make it a not-so-retro clone, as others have pointed out).

The big question to be answered when it comes to these “Chaosium inspired” sections is … whether or not they are breaches of the copyrights held by Moon Design? While I searched long and hard for a “smoking gun” which would show there had been literal copy/pasting of sections out of Call of Cthulhu (the most unambiguous form of breach), I didn’t really find anything that absolutely qualifies as such. Yes, there are stat blocks for monsters and for Lovecraft NPCs that use the same set of numbers against the same characteristics, but I’m not sure that qualifies as breach of copyright (since arguably the numbers and the names of the characteristics are both pieces of game rules … or at least that’s how they’ve been interpreted in the cases of other “retro-clones”).

In terms of narrative text in Open Cthulhu that is a literal copy of Chaosium text … I couldn’t find any examples. Of course there are *plenty* of examples where the Open Cthulhu SRD uses different words to describe effectively the same game mechanic found in Call of Cthulhu, but once again I don’t know that this is a copyright breach since rules themselves cannot be copyrighted only their textual expression. As an example of the use of different language to describe similar rules, here is the parallel text describing how Investigators gain percentiles in the Cthulhu Mythos skill when they suffer insanity:

Call of Cthulhu 6th Edition

(© Chaosium, quoted here under fair use)

Open Cthulhu

(© Open Cthulhu, used under OGL)

Insanity and the Cthulhu Mythos

Insanity stemming from non-Mythos causes yields no Cthulhu Mythos knowledge. But each time an investigator reels from Mythos-induced trauma, he or she learns more of the Mythos, and this is reflected in the arcane Cthulhu Mythos skill.

The first instance of Mythos-related insanity always adds 5 points to Cthulhu Mythos. Further episodes of Mythos-induced insanity each add 1 point to the skill.

Understanding the Cthulhu Mythos

Whenever an Investigator goes Temporarily Insane or develops a Disorder due to an encounter with the Cthulhu Mythos, he or she also gains some deeper understanding of the true nature of reality. On the first such occasion, the Investigator gains 5 percentiles in the Cthulhu Mythos skill; each subsequent occasion grants a further 1 percentile. This increase also serves to reduce the Investigator’s maximum SAN (and if current SAN is higher than this value, also causes it to drop to the new maximum).

Provenance of Rules vs Provenance of Keeper-Resources

One thing that is quite clear when looking closely at the Open Cthulhu SRD is that there is a sharp difference between the way in which it derives its “rules” content versus its material for Keeper Resources (Mythos Entities, Creatures, Spells etc).

The Rules section borrows very heavily from existing OGL rulesets — most notably Delta Green. If taken in isolation, the rules section of Open Cthulhu has about 47% of its text derived from Delta Green with another 6% from Legend. That leaves 45% of the rules-section text which doesn’t come from any OGL source. This is mostly made up of skills descriptions, rules for skills improvement, sample weapons table, and examples of rules being used. While the example text used to illustrate and clarify rules is entirely original, most of the other areas identified above are a mix of Chaosium-influenced rules and entirely original rules.

Things are quite different when it comes to Keeper Resources, largely because the primary two OGL sources — Delta Green and Legend RPG — have no OGL content for Mythos entities. In the case of Legend it’s not a Mythos game, so that isn’t surprising. In the case of Delta Green, its own OGL makes it clear that those parts of the Agent’s Handbook are off-limits when it comes to OGL re-use. This seems to have forced the Open Cthulhu writers to (a) create more “new” text, and (b) seek out some alternative OSR rulesets which have small fragments of descriptive text about Mythos creations.

The provenance of the Keeper’s section of Open Cthulhu is broken down as shown below.

The small amount of “Delta Green Adapted” material shown here represents the text supplied for each Mythos creature which describes how it should be considered in terms of the Lethality combat mechanic borrowed from Delta Green. As can be seen, when it comes to Keeper resources, there seems to be a lot which is consciously inspired by Chaosium material, although it must also be said that there is a lot of really interesting material which seems quite distinct from how Call of Cthulhu handles situations (e.g., a different take on Great Old Ones, a more restrained approach to magic, and a set of nifty guidelines for making a brand new setting for Lovecraftian gaming and adapting the Open Cthulhu rules to work with it).

One thing for which Moon Design (and others) chastised the Open Cthulhu crew upon their first SRD release was the inclusion of Mythos elements which derive from works still under copyright (e.g., those of Brian Lumley, Ramsay Campbell, etc.). The Open Cthulhu team claimed to expunge all such mentions in their second SRD … so the question is, did they succeed? In general I would have to say that they did — there are no mentions by name of non-Lovecraft Great Old Ones, Mythos creatures, or Tomes. In fact the list of Mythos entities looks surprisingly similar to that published online for the German-language FHTAGN game (which probably isn’t surprising, since that game was held up during the YSDC discussions as an example of good practice in this area). The only qualifier I would place on my observations in this regard is that Open Cthulhu — like many other games — has rolled in several unnamed or generic Mythos creature categories (e.g., “Winged Servants” or “Hounds of Time”) which seem, to a greater or lesser extent, to be allusions to specific Mythos creations without actually claiming a direct relationship to those creations. It’s another “grey area” from an IP perspective I suppose.


The point of this exercise was to look at the Open Cthulhu SRD in detail to see whether its claims of OGL provenance check out, whether Chaosium’s claims of IP violation are backed up by examples, and whether Open Cthulhu was intended as a true “retro-clone” of older Call of Cthulhu editions.

I think that the analysis I’ve presented above answers many of those questions, although the question about IP violation is obviously a multi-faceted thing. I can certainly see why Moon Design has not been forthcoming with a laundry list of claimed copyright “violations” — since such a thing would be open to argument on both sides, which likely isn’t how they would wish to pursue the matter.

Above all this, however, I would have to say that a close examination of the Open Cthulhu SRD has surprised me in a couple of ways. Firstly, it’s really apparent that the writers of this system have put a lot of effort into it — I was expecting a shoddily slapped-together affair with little consideration for gameplay, but in fact the current rules show a deft and experienced hand at work judiciously picking pieces from several sources and assembling them carefully. The second way that the SRD has surprised me is in its aim to be more setting-independent and all-purpose than the thing it seems to be trying to copy — if the goal was to provide a basic engine to power a broad range of Lovecraftian d100 games, then it substantially succeeds, although obviously would need extrapolation to meaningfully work outside its stated range of eras (early twentieth century to modern day).

It’s a real shame that Open Cthulhu has wound up in such troubled straits, since otherwise it’s just the sort of thing I would recommend to game designers looking for an adaptable d100/Lovecraft base from which to build their own creations. As it is, though, it would be a brave person that took on such an endeavour . . .


[Raw data for the statistical analysis available here; marked up version of the Open Cthulhu SRD for peer-review available on request]

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