This is an online SRD of the Cthulhu Eternal OGL RPG. It contains the core rules, along with the setting variations. I’ve compiled this from the documents released so far (see below) for easier, centralized access.

This is still a work-in-progress. See below for progress.

This page has been written in Obsidian, and published with quartz. This creates easy navigation links between the HTML output, preserving the original content in plain-text Markdown.

Table of Contents

Part 1 - Rules of the Game

Part 1 Summary - Creating a Protagonist

Part 2 - Skills

Part 3 - The Game

Part 4 - Combat

Part 5 - Equipment and Resources

Part 5 - Appendix - Equipment per Age

Part 6 - Vehicles

Part 7 - Sanity

Part 8 - Downtime

Part 9 - Game Master Resources

Part 10 - Rituals

Part 11 - Creatures and NPCs

Part 12 - Cults

Part 13 - Artifacts

Part 14 - Tomes


What is Cthulhu Eternal ?

A OGL-based d100 RPG of Lovecraftian horror, similar to Call of Cthulhu and Delta Green.

How is this different from those games?

The answer by the author on reddit captures the essence (original comment here), as compared to Call of Cthulhu:

  1. Character Creation: as others have noted, CE (like Delta Green before it) treats professions as a more detailed “skills package” which effectively means you have 6-10 skills which have a much higher base value than usual, because they’re important to your archetype. Of course there is also a points spending phase where you can further increase any skill (except the “Cthulhu Mythos” equivalent), but only in blocks of 20. This makes character creation a bit more streamlined. A character’s chosen archetype also gives a beginning number of Bonds (see below) and a starting Resources score.
  2. Bonds: Characters have a set of nominated people, groups, or societies that they are especially bonded with. CE expands on the Delta Green idea of individual bonds (people who are important in your life) by adding the second category of Community Bonds (bonds with a society, or group, or faction, or similar). Both types of bonds have a strength value from 1-20 which describes how powerfully you are associated with the person or group. This can go up or down depending on game play events (in particular SAN losses). The rating in a Community Bond defines how high ranked and important you are in the group, and as a consequence how likely it is you can influence the group or receive support from them. In this sense, Community Bonds also take over part of the role performed by the CoC skill “Credit Rating”.
  3. Resources: Each player character has a Resources score from 1-20 which denotes how much “stuff” he or she has ready access to. This is kind of the other half of the CoC Credit Rating skill, namely material wealth. Resources are an abstraction that covers all the incidental stuff that you might carry or own but which isn’t explicitly mentioned on the character sheet. As such it can be used during play as a way of checking whether some key piece of equipment might just happen to be something a character carries in his or her normal kit — a D100 roll against Resources x5 is usually made: if passed, you get the minor item. There’s a limit on how many times you can benefit from this in a scenario.
  4. Sanity: The CE system inherits a lot from the much richer approach to SAN baked into the Delta Green mechanics. The simple stuff is the same as CoC (rolling tests to determine SAN loss), but there is a lot more structure about when Disorders develop and what effect an acute episode has (in terms of game mechanics). There is also the potential to attempt to “deflect” some SAN losses and even fend off an acute episode by invoking one of your Bonds. This always involves a weakening of the Bond, and only maybe avoids the outcomes — so it’s a risky proposition that might backfire and ruin your relationships with important people and groups in your social or professional life.
  5. Combat: As others have pointed out, Combat in Delta Green (and by extension CE) is much more streamlined compared to CoC, with every combatant getting exactly one dice roll in a combat turn, whether it be an attack, fight back, or dodge. If you normally act late in the turn sequence but get attacked by a quicker combatant, you can choose to immediately have your Dodge or Fight Back resolved and potentially inflict damage on the person who originated the attack. Once you have had a roll the result “sticks” with your character for the rest of the turn — so if someone else subsequently attacks you in the turn the “stuck” result is a defensive roll that gets compared to their attack. Combat is also more deadly in DG and CE because of the possibility of weapons that deal Lethal damage — potentially killing outright with a successful attack. Automatic weapons which can sometimes bog down combat in CoC with loads of dice rolls are resolved using Lethality tests instead, which is a single roll.
  6. Downtime: There are some specific rules and options for running short scenes in between adventures that help to explore both the character’s development and also the ways in which the consequences of the scenario events alter their personal lives. This is especially the case where Bonds weakened or broken during play can be explored — how does that manifest and what does it say about the character and their community? New Bonds can be forged during Downtime and damaged minds can be (maybe) healed.
  7. OGL: One of the big appeals of CE is the openness of its rule system and also the Open Mythos (game stats for Public Domain creatures, cults, tomes, etc invented by Lovecraft). This makes the CE system an attractive platform for indie publishers who want full control over their creations, as afforded by the OGL.

Rules and game content is OGL. More information at https://cthulhueternal.com/.

Check out their SRDs on DriveThruRPG:

TODO expand


Work in progress

  • clean numbers in headers
  • added Classical SRD to links
  • fix some “see” references (Part 1)
  • add Future Age content
  • add NPCs
  • Open Mythos
  • replace about:blank in cults
  • replace all “See” references with links
  • add Medieval Age content
  • add Jazz Age content
  • add pregens

Collaboration and Submissions

If you want to fix or submit something in this webpage, clone the repository, open it in Obsidian. Make your edits and then open a PR.