So you want to make a game but are unsure about writing rules from scratch (also a note on writing modules/adventures/mysteries using existing systems)….

Well great news! Many games live their lives as hacks for other games/rule systems. This means that you can start with a framework from which you can adapt to serve your idea/concept.

SRD (System Reference Documents) is a way game designers share their work. Often it includes what can be used, and how, so that other designers can iterate and create new games.

Below are some examples of different SRDs that you can use as a starting point in designing your own game. Many games have an SRD, but the one’s I’ve included have robust communities around them and are versatile enough to meet a myriad of needs.

Games have different licenses that dictate what can be used from the core text. Be sure to check their use/licenses to make sure you meet the requirements in your final product (an inclusions of established statements, attributions, etc).

A Step-by-Step Guide to creating a TTRPG SRD by Desolate Drifter @GulluthGultch is a comprehensve guide to creating your very ownn TTRPG SRD (that is also free).

Example SRDs

  • Liminal Horror by Goblin Archives: A rules lite modern cosmic horror hack of Cairn (which combines Into the Odd and Knave). It adds a stress & critcal stress fallout mechanic to those systems.
  • Cairn by Yochai Gal. It is an adventure game where players explore dark and mysterious woods. It is based on Into the Odd and Knave.
  • Vaults of Vaarn by Leo Hunt (with SRD by Desolate Drifter) is a techo filled game of a dying sun over a blue desert of science fantasy adventures.
  • PINKHACK by Monkey’s Paw Games. Rules for Fantastic Role-Playing Wargames, Monkey’s Paw Games has created a combination of the Whitehack and into the Odd.
  • Beak, Feather, & Bone by Tyler Crumrine. This rule framework is one that involves building a world through collaborative map making.
  • 24XX by Jason Tocci is a framework of rules that works as a modular plug-and-play toolkit. Rules lite and dynamic, 24XX SRD is axtremely versitile and includes a plethora of templates and resources to help designers get started.
  • Tunnel Goons by Nate Treme. Tunnel Goons is an extremely straightforward system that fits on half of a page.
  • Trophy by Jesse Ross. Trophy is a narrative system that focuses on the doom that befalls the characters. Beware the horror and doom that awaits.
  • Wretched & Alone by Matt Sanders & Chris Bissette. These are solo journaling games that focuse on struggle, survival, and striving to achieve.

-ARCANUM by momatoes is a great example of an SRD that provides you with the tools to make a game using the SRD. In momatoes own words “If you want to make a creature codex based on ‘90s Variety Children Shows gone wrong, Spells & Techniques for a cyberpunk setting, or a rules modification for games running only an hour long, it’s now Legally Blessed (™) if you read and follow the common-sense guidelines from the” ARC RPG license.

Note: Sometimes you don’t want to write a hack or new game and instead want to write an adventure, mystery, or modul. Luckily all the advice in this guide still works for that. SRDs are still great because they can provide rules references that you can use to make your zine compatible. I wrote a small twitter thread on the different supports Liminal Horror provides for people who are wanting to write their own mysteries/sessions/adventures. That can be found here: Interested in writing cosmic horror adventures?

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Liminal Horror was written and designed by Goblin Archives