The game
A Geist is a kind of spirit that was once a ghost but has given up their mortal identity. Instead they have become an embodiment of the ideas and imagery of their own deaths.
Players portray Sin Eaters who have died and returned to the world of the living. Unlike vampires, however, Sin Eaters (also called the Bound) are not undead, but rather living beings bound to fundamental forces of death. Upon the first death, every Sin Eater is approached by a Geist, an embodiment of an aspect or personification of death. In exchange for being returned to life, Sin Eaters allow the Geist to accompany them, effectively merging into each other in a symbiotic relation with the “human” in control. Upon this return to life, the Bound discover that they can see and interact with the restless shades of the dead, and must choose what to do with their second chance at life. In all instances, Sin Eaters are forced to deal with the dead, whether through altruism, greed, or just the plain fact that the dead will not leave them alone.
Every Sin Eater has a Threshold, relating to the way in which they died. Thresholds can be somewhat fluid, depending on what aspect of death the Sin Eater-to-be focused on at the moment of death. For example, someone who drowns could be either one of the Prey, who are killed by nature, or one of the Silent, who die from deprivation (a lack of oxygen), or even one of the Torn, if they are held under water.