For use with Cairn

Discover an array of hacks, thrilling adventures, and expansions for the Cairn SRD ecosystem by Yochai Gal.



Intrepid spacers ply the vastness of the Five Galaxies in search of fortune and glory. This is Plerion, a sci-fi hack from Cairn designed to play radiant space opera.

Plerion is an adventure game for one referee and at least one other player. Players act as hardened spacers exploring, exploiting and commerce through the vastness of space in the far future. 

Plerion: Solo Starfarer

Embark on a journey beyond the stars with Solo Starfarer, the essential companion to the Space Opera Adventure Game, Plerion! If you've already delved into the cosmos with Core Book, then you're ready to take your space-faring adventures to the next level.

In Solo Starfarer, you won't find the basics of character creation, combat, or equipment. Instead, dive into a galaxy of possibilities where your imagination knows no bounds. This booklet is your toolkit, filled with flexible guidelines and modular components that you can customize to suit your gaming style.

Plerion: The Five Galaxies

Welcome to Plerion: The Five Galaxies, a journey through a universe filled with intrigue and exploration. This guidebook, complementing the Core Rules and its expansions, unveils the diverse realms of five interconnected galaxies.

Navigate the Charted Space, from the bustling trade hubs of the Milky Way to the enigmatic reaches of the Magellanic Clouds. Encounter an array of species, from the influential Lynem to the mysterious Wrulisu, each with their own stories and struggles.

Delve into the politics and power plays of major empires and learn about the advanced technologies that propel civilizations across light-years. Whether it's exploring unknown systems or engaging in interstellar trade, this book offers a detailed framework for your adventures.

Plerion: The Five Galaxies is your gateway to a universe of possibilities. Chart new courses, encounter diverse cultures, and face the challenges that lie in the vastness of space. The stars are calling.

The Book of Cosmic Creatures

Dive into the uncharted depths of the cosmos with The Book of Cosmic Creatures, a science fiction bestiary that brings an unparalleled level of strangeness and depth to your Plerion campaigns and beyond. Compatible with Cairn, Into the Odd, and adaptable to your favorite sci-fi ruleset (such as Monolith of Meteor), this compendium is your gateway to the extraordinary.

From the vast emptiness of space to the most hidden corners of planetary ecosystems, discover creatures that defy imagination. Encounter common spacefaring animals, confront colossal space leviathans, and prepare to face the unfathomable: interdimensional beings and quantum entities that promise to elevate the weirdness and danger of your adventures.

Other Cairn Hacks


Thálassa is an adventure game for one facilitator (the odigós) and at least one other player.

Players act as fearless explorers of the Mediterranean of the Mythical Age, studded with mysterious islands, thick forests, legendary creatures, labyrinths and dangers.

Golden Idol

Golden Idol is an archeological thriller action-adventure game set in the modern world.

You are members of LARA (Legendary Artifacts Recovery Agency), charged with discovering and finding valuable artifacts around the world in remote places, among the vestiges of lost civilizations.


Welcome to Taintedweald, a post-apocalyptic forest-crawl set in a small region of an undefined world.

This mini-setting inspired by the works of Hayao Miyazaki  is compatible with Cairn

SCP for Liminal Horror

Welcome to the SCP Foundation, a world of unexplained phenomena and anomalous objects that threaten the very fabric of reality. 

You will immerse yourself in the horror and mystery of the Foundation, using the Liminal Horror system to navigate the dangers of containment breaches, rogue agents, and unimaginable terrors from beyond the veil.