Beneath the veneer of Imperial glory, a dark shadow spreads. This is the world of Cohors Cthulhu, a tabletop roleplaying game set in a 2nd-century Roman Empire besieged by cosmic horrors. You are heroes bound by trauma and solemn oaths who must face an unthinkable foe: the fathomless Outer Gods and the baleful horrors at their command. From the heart of Rome to the dark edges of the Known World, their influence corrupts all it touches. This is the Hidden War.