Cthulhu Eternal System Reference Documents

The cruel and dark heart of the Cthulhu Eternal system lies in its free/open rulesets. Each is a fully self-contained set of game mechanics, tailored to Cthulhu-infused tabletop RPG sessions set in a specific era, whether past, future, or fictional. The rulesets are each embodied in a “System Reference Document (SRD) which describes the rules for creating characters, putting them in harms way, and perhaps even allowing them to live to tell of their harrowing experiences.

Each SRD is a PDF of approximately 100 pages, the contents of which are fully Open Content and released under the (Wizards of the Coast) OGL. That means you can use the material in any way you wish, whether it’s simply using the rules as written to run a scenario of your own devising, or borrowing substantial parts of the game mechanics (or the whole thing!) to form a platform for a brand new RPG you want to build.

While each SRD varies in its contents, we have tried to keep the over-arching game system consistent across all of them. We’ve also (broadly) organized each according to the following structure:

Part 1: Rules of the Game

  • 1.0          Core Game Concepts
  • 2.0          Creating Protagonists (the term given to player characters in Cthulhu Eternal)
  • 3.0          The Game (skills, tests, willpower)
  • 4.0          Combat
  • 5.0          Equipment
  • 6.0          Vehicles
  • 7.0          Sanity
  • 8.0          Downtime (developing protagonists between adventures)

 

Part 2: Game Moderator Resources

  • 9.0          Maddening Revelations
  • 10.0        Supernatural Effects

 

Part 3: Game Building Resources

  • 11.0       Designing New Archetypes
  • 12.0       Translating Creatures from D100 Games
  • 13.0       Gumshoe Creature Conversion

Open Rules for Modern-Day Settings

Cthulhu Eternal - Modern Age Banner

This version of Cthulhu Eternal is specifically tailored to support Lovecraftian games set in the “modern day” – that is, the era we live in (give or take a decade or two). 

This is an attractive option for a game setting: after all, everyone is already familiar with what life is like in our current real world so it’s not something that needs to be particularly explained or portrayed for players. Also, the range of research resources that are available to describe the real world of our era is vast – if you want to find some detail to add color to your game version of a place or  real-world organization, just go to a search engine or Wikipedia and you’ll find more than you could ever use.

Modern-day Cthulhu Eternal is designed for games in which Protagonists are everyday people who have somehow crossed paths with the Cthulhu Mythos. Lacking any kind of official network to support them in their investigations, they tirelessly slog at uncovering the true nature of the world and doing what needs to be done to ensure humanity’s continued survival.

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Cthulhu Eternal Char Sheet Modern - Front (sml)

Resources for Modern Era Cthulhu Eternal

The Modern Era SRD Bundle contains the full text of the tailored rules (in both PDF and RTF formats). It also includes attractive 2-sided character sheets — a fillable one (for use with Adobe Reader, only) and a high-res printable version.

As well as these bundled resources, the following might be helpful to players or GMs running games using this SRD:

Open Rules for Post-Apocalyptic Settings

APOCTHULHU is a fully-featured RPG capable of supporting any Lovecraftian Post-Apocalypse setting you could imagine, whether a dystopian future or an alternate past.

While you can purchase fully-illustrated versions of the APOCTHULHU rules (and even a quickstart), the entire ruleset is also available for free as a System Reference Document. There is also a glossy anthology of diverse scenarios for APOCTHULHU called Terrible New Worlds.

Use these rules to give life to your own ideas of what the world might be like after the terrible forces of the Mythos have finally overthrown humanity … 

Did the players fail in their efforts to foil the schemes of the evil forces behind a traditional scenario or globe-trotting campaign? Rather than just fading to black, you can simply move play to whatever dark parody of our world survives the “Apocalypse” that they did not avert …

Open Rules for Historical Settings

Cold War Banner

This version of Cthulhu Eternal focuses on the mid-20th Century, and in particular the shadowy world of the “Cold War” that waxed and waned roughly from the end of World War II to the mid-1990s, ending with the breakup of the Soviet Union. Although, truth be told, this setting could be used up to September 11, 2001, with little modification. After September 11, 2001 and the start of the wars in Afghanistan and Iraq, many intelligence agents saw their mandate drift or shift from intelligence gathering to more direct paramilitary action.

It’s a period ripe for inserting cosmic horror. The world is already living in fear of imminent nuclear annihilation. The geopolitical situation throughout the world is one of paranoia, with nations using subterfuge to fight “proxy wars” and accusing their opponents of rampant spying. Into that brew of distrust, fear, and deception it is easy to sow the seeds of Mythos horror. Whether they are trained intelligence operatives digging to find the truth or everyday people stumbling onto it, it is easy to find ways for Protagonists to learn hints of the true history mankind wasn’t meant to know and can never comprehend. 

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Cthulhu Eternal Char Sheet Cold War - Front (sml)

Resources for Cold War Cthulhu Eternal

The Cold War SRD Bundle contains the full text of the tailored rules (in both PDF and RTF formats). It also includes attractive 2-sided character sheets — a fillable one (for use with Adobe Reader, only) and a high-res printable version.

As well as these bundled resources, the following might be helpful to players or GMs running games using this SRD:

Cthulhu Eternal - Jazz Age Banner

This version of Cthulhu Eternal is specifically tailored to support Lovecraftian games set in the Jazz Age – that is, the world as it was in the early 20th Century (between the World Wars; primarily the 1920s and 1930s). 

This is an attractive option for a game setting – and one that has been used many times – for one simple reason. When H.P. Lovecraft was writing his uncanny tales of weird horror, he frequently chose to set them in the world that was most familiar to him and his readers: the present-day world at the time they were written. 

Given that those tales were penned between 1920 and Lovecraft’s death in 1937, there are plenty of examples of original creations that take place in the inter-war era we’ve termed the “Jazz Age.” Those stories can easily serve as great sources of inspiration for your own scenarios – and best of all they are reliably authentic to the period (because they were written by someone living through it).

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Cthulhu Eternal Char Sheet Jazz - Front (sml)

Resources for Jazz Age Cthulhu Eternal

The Jazz Age SRD Bundle contains the full text of the tailored rules (in both PDF and RTF formats). It also includes attractive 2-sided character sheets — a fillable one (for use with Adobe Reader, only) and a high-res printable version.

As well as these bundled resources, the following might be helpful to players or GMs running games using this SRD:

Cthulhu Eternal - Victorian Era Banner

This version of Cthulhu Eternal is specifically tailored to support Lovecraftian games set in the Victorian Age – that is, the world as it was in the mid-to-late 19th Century (when Queen Victoria ruled the British Empire). Outside of the Jazz era, this might be the second most popular time period for Lovecraftian gaming due to the rich history and atmosphere that this time period provides.

While before Lovecraft’s time, the Victorian Era was an important time for horror. During this time period, important works of cosmic horror, gothic horror, science fiction, detective fiction and weird fiction were brought into the collective imagination and forever changed the literary landscape.

For detective fiction, this is the period of famous literary sleuths whose legacy is embedded in RPGs which revolve around solving mysteries (as most Lovecraftian games do). In the horror landscape, important characters such as Dracula, Frankenstein, The Invisible Man, Dr. Jekyll and Mr. Hyde, were born. In science fiction, Professor Challenger and Captain Nemo shared bold and often terrifying visions of the future as the world was rapidly changing due to new and exciting technologies.

DOWNLOAD
Cthulhu Eternal Char Sheet Victorian - Front (sml)

Resources for Victorian Era Cthulhu Eternal

The Victorian Era SRD Bundle contains the full text of the tailored rules (in both PDF and RTF formats). It also includes attractive 2-sided character sheets — a fillable one (for use with Adobe Reader, only) and a high-res printable version.

As well as these bundled resources, the following might be helpful to players or GMs running games using this SRD:

Age of Revolutions Banner

This version of Cthulhu Eternal is specifically tailored to support Lovecraftian games set the period from approximately 1750 to 1850. This was an era when the world was on fire, buring with the flames of Revolution (both literally and figuratively).

It was the century which saw both the American and French Revolutions, as well as several epic, globe spanning wars (the Napoleonic Wars and the Seven Years’ War/French and Indian War, just to name a couple). It is also the century in which the colonial expansion of the European powers — and their brutal oppression of indigenous peoples across many continents — was at its absolute peak. It’s the time of the founding of the penal colonies of Australia, but also the time of the so-called Age of Enlightenment and the Industrial Revolution . This era also spawned the first of the bleak novels that would later be called “gothic”, as well as the genteel society of the Regency period.

Regardless of whether you wish to weave your Lovecraftian tales in amongst the tumult and upheaval of war, or in quiet places where the distraction of such world re-shaping events has allowed dark things to grow unnoticed … the Age of Revolutions offers many intriguing opportunities. If you’re willing to scratch the surface of its often-brutal world …

Age of Revolutions SRD Cover 900
Cthulhu Eternal Char Sheet Age of Revolutions - Front 150

Resources for Age of Revolutions Cthulhu Eternal

The Age of Revolutions SRD Bundle contains the full text of the tailored rules (in both PDF and RTF formats). It also includes attractive 2-sided character sheets — a fillable one (for use with Adobe Reader, only) and a high-res printable version.

As well as these bundled resources, the following might be helpful to players or GMs running games using this SRD:

More SRDs in development ... check back later.

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