In the world of Cain, humanity is a vast open wound, bleeding their pain, their joy, their sorrow, and their dreams into the psychic mélange that makes up the background radiation of our reality. Sometimes though, that wound is too deep, and the background becomes so dense that it becomes something physical. To the titular organization from which this TTRPG gets its name, these beings are known only as SINS; and for the safety of mankind they must be exorcized from our reality. Your players will inhabit the roles of those dedicated to this practice. Exorcists; psychic agents whose own personal damage is at least currently manageable, sent to investigate and discover the source of the SIN. Designed and written by Tom Bloom (Kill Six Billion Demons), this game is part X-Files, part Chainsaw Man, and all about playing emotionally messy psychics trying to hold themselves together long enough to discover the traumatic event from which a psychic threat emerged.
-Excerpt from "Picking Your Second System" over on Goonhammer.com