The PC's are clones or simulacrum of Ancient Gods who are no more, either having been destroyed, banished, or forgotten about. The PC's of course have no Godlike powers, because they were made when the said God's were once mortal. They have been kept in temporal stasis in a deep underground crypt until someone finds them ( a party of adventurers, a wizard, or even a Lich would be nice).The PC's have no recollection of who they are or how they came to be here, all they know is their names and have a deja vu about everything. Plus a strange sense of kinship with one another. As a substitute you can have them entombed in a iceberg or a glacier, and have northmen come across them to chip them out of the ice (this is the scenario I used once).