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The Vampires of Nightworld(1981)
(The second book in the Nightworld series)
A novel by David Bischoff
For five hundred years a mad computer scientist who called himself Satan ruled the nights of the planet Styx, each sundown unleashing hordes of cyborg creatures--werewolves, vampires, dragons, and worse--to terrorize what had once been the idyllic Victorian villages of an interstellar pleasure world. Then satan was killed by Geoffrey Turner and young Oliver Dolan--and things grew worse, for Satan's creations, left to their own devices, quickly began to terrorize the days as well as the nights. It was left to Oliver Dol an to pacify the creatures and defeat Satan's last, most insidious weapon--before all men were turned into Zombies.
Used availability for David F Bischoff's The Vampires of Nightworld
June 1981 : USA Mass Market Paperback
September 2015 : USA, Canada, UK Kindle edition