Click the Files Below to Download the Early Access Preview of FAOS

Note this is still a work in progress

Rules V1.6

Creatures V1.6

Adventurer’s Journal V1.4


What is FAOS?

The Fantasy Adventure Operating System (or FAOS) is a tabletop roleplaying game system created by Gord Sauer based around the d20 dice. The World of Faos is a fantasy world which uses FAOS game system. In the FAOS game system, every living (and sometimes undead) thing is a Creature. Creatures controlled by the Players are called Adventurers. All other Creatures are controlled by the Game Master (GM).

All Creatures can perform Actions. The success or failure of these Actions are determined by Ability Checks and Difficulty.

Sometimes Creatures controlled by the GM will perform an Action against the Player's Adventurer. In these cases, the GM rolls the Creature's Ability Check and the Player roll’s their Adventurer's Ability Check to determine the Difficulty value. Other times, the Player's Adventurer will perform an Action by rolling an Ability Check and the GM will determine the Difficulty value. Ability Checks are done with the roll of a d20 dice and then you add your Creature's Ability modifier total to increase the total. When the Ability Check total meets or beats the Difficulty value, the action is a success.

In summary, everything you do in FAOS has a certain Difficulty and your Ability Checks must overcome that Difficulty. Ability Checks will allow your Adventurer to defeat monsters and find the treasure. As your Adventurer grows more experienced, your Abilities increase and you get to decide how your Adventurer becomes the next great hero.

Why Another TTRPG?

I will be frank, there is no need for another TTRPG. But I like creating stuff like this and if someone else can take some of these mechanic ideas and move it forward, that would be all worth it. I’m an engineer and I’ve always like creating systems and refining those systems in my work. I still love D&D but there are somethings that I’ve always wondered what it would be like if it worked a different way.


I would like to acknowledge some of the people and companies that inspired me for FAOS:

D&D5e TTRPG by Wizards of the Coast

Shadow of the Weird Wizard TTRPG by Robert Schwalb at Schwalb Entertainment

Shadowdark TTRPG by Kelsey Dionne at The Arcane Library

Musings by Matt Colville at MCDM Productions

Musings by Professor Dungeon Master at DungeonCraft

Brainstorming and play-testing by Mike Schneider

Brainstorming and play-testing by Jason Gau

Brainstorming and play-testing by by Nick & Will Schneider

Brainstorming and play-testing by Art Vanderby


The game mechanics of the FAOS TTRPG is free to copy, revise and include in your own game systems with an acknowledgement to FAOS and Perilous Pursuits. The trademarks FAOS, World of Faos and Fantasy Adventure Operating System are owned by Perilous Pursuits ©2023 and shall not be used without prior written permission.