Vampire Rain: Altered Species is an intense game that takes place during a dreary night in a suburban, west coast city in the US. For some time now, mankind has been battling the ferocious and terrifying Nightwalkers, a race of superhuman vampires who crave human blood. People have been disappearing at night; the lucky ones are found dead, but those less fortunate are reborn as Nightwalkers, and are bound by instinct to forcefully recruit unwitting victims into the Nightwalker army. Gamers take the role of John Lloyd, a member of a US special government unit created to defeat the Nightwalkers, and the only human to ever survive a physical encounter with them.