The Underworld is the realm of the dead run and operated by Aymonus, the God of Absolute Death. It has various sectors and regions, and is one of the most obscure realms in existence. It is the base of operations for Death.
It is located somewhere within the Far Realm, and is where all souls come to for their final rest.
Death himself commands a group of four, known as the Black Riders. The leader of these Riders becomes the next Death, should one be needed to replace the old. Beneath these five individuals is an army of death gods and reapers, who all work tirelessly to keep the balance between life and death.
The realm itself is composed of various High Cities, which float above the Grand Wastes, filled with the bones of sinners and evil doers. Those who are found guilty of unforgivable sin and refuse to repent are cast down into this infinite plane of emptiness and consumed by their fellow husks. Each High City has a populace of souls, separated by the magnitude of their lives and their good deeds. The highest honors go to those who were obscure in life but committed themselves to others, those who used their great status to better the world around them, the heroes who help defend the realms, and the great scholars who spread knowledge and wisdom.
The Realm is briefly visited when the Player wakes up in the Realm of the Dead, and escapes. It is possible the Player may have to return.