It is the 24th century, and mankind has only recently begun expanding its reach to the star systems nearest our own Solar System.
A dark and terrible secret is buried within a misshapen moon nestled in the massive asteroid belt of the Epsilon Eridani system. Pythos colony was built there ostensibly to exploit the planetoid's mineral resources, but now they've disturbed a kind of evil that lurks beyond the fringes of our comprehension.
Through an ever-changing labyrinth, you will remold yourself into a cybernetic killing machine using the powerful technologies of a long-dead alien civilization. With these new-found weapons, you will pave a path of aberrant corpses toward the greatest threat to mankind ever encountered.
CTHON is an old school science-fiction first-person shooter, where you become a cybernetic weapon against the dark legions of a powerful evil entity - known only as Cthon - who lurks within the planetoid. It is a classic space horror game, inspired by the likes of Doom, System Shock, and Quake.