You play as Daniel Garner, a regular guy who gets killed in an horrific car crash while taking his wife out for her birthday. She, being the saintly woman she is, gets admitted to Heaven. Daniel, due to his shady past, does not. He finds himself in Purgatory -- a place somewhere between Heaven and Hell. It isn't long before Daniel is recruited by his "caseworker for the dead" to fight the minions of Hell. You see, Lucifer is plotting to overthrow Heaven, and is using Purgatory as a staging ground. Your offer is simple: stop Lucifer's armies and earn your heavenly reward.

Painkiller is a first-person shooter set in the sinister world of gothic horror. As the mercenary known as Painkiller, players are charged with the task of eliminating the undead in whatever lair, tomb, or residence they may be lurking in. Dressed in a black overcoat and wearing sunglasses to protect himself from the harsh glare of sunlight, Painkiller has earned a reputation for his no-nonsense approach to demon hunting. Yet he also hides a secret: a pact with a demon has granted him special powers at the expense of his humanity.

Painkiller must fight his way past hordes of undead creatures while freeing whatever is left of their souls. With every 100 souls collected, Painkiller can transform into a ghastly creature himself, using its physical strength and ferocity to engage multiple demons at once. Players will also have at their disposal an arsenal of ranged weapons, all of which feature primary and secondary attacks. Painkiller uses the Havok physics engine (Thief III, Deus Ex: Invisible War) for its interactive 3D environments and details such as moving clothes, rippling water, and crumbling walls.