In Eldritch Instinct, players act as curious investigators of the strange and unexplained. They will run from delusional cultists, hide from stalking shadows and face terrifying monstrosities. And they will change - through encounters with the unnatural forces of the Mythos and the limits of their own Humanity. The game was designed to run scenarios and campaigns using streamlined rules while following the axioms of the old school style as described by Ben Milton, Steven Lumpkin and David Perry in the Principia Apocrypha. Written by Linus Weber.

Download the PDF with images and practical layout from here. Print the PDF using the ‘booklet’ setting and staple-bind the pages to craft your own digest or A5 sized booklet as shown in this video. The source files are available in other formats (including Markdown, OpenDocument Text) here.

The Eldritch Instinct SRD is licensed under CC-BY-SA 4.0 and is is derived from Yochai Gal’s Cairn SRD (

This is a game that values community contributions! Currently, this is a very early playtest version and I’m very interested to hear what you think of it and how your games using these rules went. Please join the Discord Server to let me know and become a part of the development process!

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