Support for Cthulhu TTRPG Gamers & Game Creators

Supporting Cthulhu's Devotees

Players & GMs

Every gamer needs more scenarios.

We host and publish libraries of free and affordable scenarios, plus other resources to make your game better.

Glossy Tentacle

Making Life Easier for Scenario Writers

Do you have a Cthulhu-themed roleplaying scenario or globe-trotting campaign (or a killer  idea for one)?

Sharing it with the world can be a complex tangle of licensing headaches … but our Open platforms provide easy alternatives for creators to self-publishing their works.

Free Resources for Game Developers

Open rules engines. Open libraries of game resources and elements.

All available to become components powering your new game creation. Pick and choose material that supports your vision.

"In his house at R'lyeh, dead CTHULHU waits dreaming"

Who We Are

Who are we?

Cthulhu Eternal was created for one simple purpose: to make life easier for creators, “homebrewers”, and small-scale publishers of Lovecraftian horror RPG content.

We do this by offering open-source rules and content, which is available for ANYONE to recycle, remix, or reuse in their own games or scenarios (or anything else for that matter).

We exist to make it simpler for new voices to get their ideas published and shared with others who share a love for cosmic horror and tabletop roleplaying games

Submit to Us :

Submissions [at]


How can you

Use our Stuff?

Tabletop Roleplaying Games are fuelled by two complementary things — rules engines which describe how the (uncaring) universe reacts to the actions of characters controlled by players, and narrative elements that go into making up a scenario or adventure.

On this site we host both types of “fuel” to help power games, whether run in a traditional mode or adapted to some other way of playing.

Here you will find detailed (and fully free/open) rules engines offering hundreds of pages of tailored game rules. You will also find all manner of scenario elements … not to mention fully-realized scenarios that you can pick up and play with nothing more than the free content you download from here!

Free Rulesets, provided as OGL System Reference Documents

Free and open game mechanics, each tailored to describing tales of cosmic horror set in a particular era of our world's past, present or future. Each is a self-contained RPG (with full rules for character generation, skills, combat, the mental toll of the Mythos, and so on).

Use them to play a tense one-shot game, or borrow mechanics from them to fuel your brand new RPG.

Open Library of License-Free Mythos Threats and Powers

Every game of cosmic horror needs a supply of Unnatural monstrosities, whether unnameable things from other dimensions, or uncaring alien gods whose affairs occasionally intersect with careless mortals.

We love using the horrors from Lovecraft's public domain fiction, and lovingly host versions of those horrors statted for Cthulhu Eternal. We equally love brand new original creations in the cosmic horror tradition -- so we host CE statted versions of some of those here as well. Plenty of options for making characters wish they hadn't ventured out away from their safe island of ignorance.

Free Repository of Community-Created Scenarios, Variant Rules, & Resources

The strength of a community-based game is that anybody can contribute their ideas into the "melting pot" -- whether those come in the form of fully-realized campaigns of cosmic horror, or just an idea for a new character type or tweak to the default game mechanics in a System Reference Document.

We host a library of community-created content, to make it easier for users of our game mechanics to see what others have wrought ... and use them as the foundation for still further creativity.

Other Cool Sites to Check Out

From the Cthulhu Eternal blog

Latest News

Released Today: Our First Medieval Scenario - Hot on the heels of our release last month of the Cthulhu Eternal Medieval SRD, we are pleased to announce the release of the first PDF scenario playable with those rules. The Lord of Nombrecht is a fairly chunky and investigation heavy adventure set in the Holy Roman Empire (modern-day Germany) anytime from 1000CE to
+ Read More
Cthulhu Eternal Medieval SRD Released! - It never rains but it pours ichor from the interstitial void. After having a fairly slow release schedule for the end of 2022, we’re now in the enviable position of announcing the release of yet another Cthulhu Eternal SRD that our team have been slogging away on for a while — this one is the
+ Read More
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
+ Read More