Fathom: Core Rules

Intricately painted ceilings and walls of a world that once was give way to great corridors clotted with rails and shambling masses; tunnels branching and yellow-lit with artificial fluorescent lights. Vast areas go unmaintained; leaking and dangerous. Sections of the underground are deserted and unfinished; sloppily abandoned long ago. There are well trodden paths leading to “cities”; areas locked down and ruled with iron fists. These are the last vestiges of civilization aside from the communities dwelling in the unexplored caverns of Earth’s crust. Ancient sealed air locks lead to the great ocean, a strange dark land far from the sun’s illumination. Strange things happen there, and all those who sneak into the watery world-grave fear the stalking terrors of the deep. The little gear you have is well worn and battered; either scratch built or generations old. Above are the ruined Art Deco remains of the past. Below is a brutalist hellscape. Something strange and alien exists even deeper than that. This is Fathom.

Within this free text-only module, you will find everything you need to create a character in Fathom, as well as all equipment, backgrounds, abilities, travel guidelines, and rules for rolling and fighting. What you will not find is our comprehensive menagerie of monsters, and the trove of countless treasures found in the World Grave. In addition, rules for vehicles and upgrading equipment, as well as the extensive “entomb” mechanic which consists of riveting boons and curses have been reserved for the core three books.