The Dark God is the chief antagonist of the D&D based videogame Eye Of The Beholder III: Assault On Myth Drannor.
The Dark God first appeared as a cloaked figure asking for aid to stop an evil Lich who was supposedly corrupting an ancient fallen kingdom kingdom known as Myth Drannor and provided a group of adventurers with a map as well as a teleportation spell in hopes they would aid him.
However after slaying the Lich the adventurers are suddenly betrayed when the Dark God materializes and steals the Lich's power, gloating about how he would use it to destroy the entire world - he then took command of a sacred temple and began to defile it, leavng the adventurers to rot.
Yet the adventurers braved the evils of the temple and pursued the Dark God, in gratitude for the adventurers' work in restoring his temple the benevolent god known as Lathander aids the team, offering them healing via his statues as well as informing them that if they slay the Dark God's physical form he and his fellow deities shall ensure the evil entity can not return to plague the mortal plane.
Thus the adventurers make their way to the Dark God and face him in battle, he is a fast and agile opponent with a very nasty one-hit "death touch" - yet once defeated Lathander appears once again to close the Dark God's portal and informs the adventurers that with the Dark God's physical body gone he and his fellow deities are now working to ensure the entity can not return: just as he had promised.