The Fantasy Adventure Operating System

What is FAOS?

The Fantasy Adventure Operating System (or FAOS, pronounced "Fey Oss") is a FREE Tabletop Roleplaying Game (TTRPG) system created by Gord Sauer based around a “roll over” Difficulty Class (DC) Skill Check dice system using 2d12 dice. The World of Faos is a fantasy world which uses the FAOS game system. In the FAOS game system, every living (and sometimes undead) thing is a Creature. Creatures controlled by the Players are called Heroes. All other Creatures are controlled by the Game Master (GM).

All Creatures can perform Actions. The success or failure of these Actions is determined by Skill Checks done by the Players. The skill check must meet or beat the Difficulty Class (DC).

Sometimes Creatures controlled by the GM will perform an Action (for example; an Attack) on a Hero or vice-versa. The GM does not roll any dice (I know, it’s a little crazy). The Player rolls a Skill Check to determine if their Hero’s action was successful to defend against the opposing Creature’s Attack.

In summary, everything you do in FAOS requires a Skill Check that must overcome a DC. You want to roll high to succeed. Skill Checks will allow your Hero to defeat monsters and find the treasure. As your Hero grows more experienced, it will become easier for your Hero to succeed.

Why Another TTRPG?

There really is no need for another TTRPG. But I like creating stuff like this and if someone else can take some of these game mechanics and move the TTRPG industry forward, that would be worth the effort. I’m an engineer and I’ve always liked creating and refining systems in my work. I have played several TTRPG systems and I’ve always wondered what it would be like if some of these game mechanics from different systems were combined or worked in a different way. FAOS is that vision by trying to reduce the workload of the GM by moving all rolls to the players. This has the added benefit of keeping the players engaged and active even when it’s not their turn. It also tries to streamline combat while still adding just enough crunchy strategic options for the players. Why use 2d12? It takes some of the big “swinginess” out of using a d20 (at least mathematically).

About Me

My name is Gord Sauer (GoGo DM) and I’ve been playing D&D weekly since 2016 here in Canada. Perhaps it was the logical/process part of me as an electrical engineer that drove me to create a TTRPG ruleset like FAOS. Perhaps it was just the joy of creation. Whatever the reason, it was a very fun and worthwhile endeavour. Enjoy your adventures in FAOS.

Also check out our TTRPG space www.perilouspursuits.com where we have several live-play adventures using various TTRPGs.

Acknowledgments

I would like to acknowledge some of the game systems that inspired me for FAOS:

D&D5e TTRPG by Wizards of the Coast

Shadowdark TTRPG byThe Arcane Library

DC20 TTRPG by the Dungeon Coach

Daggerheart TTRPG by Darrington Press

Vagabond TTRPG by Land of the Blind

Mythras TTRPG by The Design Mechanism

Legal

Not for resale or redistribution. Permission granted to copy for personal use only and with an acknowledgement to FAOS and Perilous Pursuits. The trademarks Perilous Pursuits, the Perilous Pursuits logo, FAOS, the FAOS logo, World of Faos, Fantasy Adventure Operating System, FAOS Cards and their text and graphics, Action and Legendary Tokens and their graphics, are owned by Perilous Pursuits ©2026 and shall not be used without prior written permission from Perilous Pursuits.

Images

As a free TTRPG, FAOS was created as inexpensively as possible with a lot of love and long hours. All the artwork was created using either artificial intelligence image generators or a combination of many other images.

Top Image

Phenola the Druid watches the broken moon Ula drift across the sky with mysterious explosions in the debris field.