The game casts you in the role of Daniel Garner, trapped in Purgatory following a fatal car crash in which he and his wife both died. His wife, being the nice, pure sort, went straight to Heaven, but Daniel has work to do before he's allowed in. Specifically, he is told of Lucifer's generals preparing a war between Heaven and Hell, and he is the one chosen to stand in their way by, I quote, "destroying everything in [his] path". And there's a lot of destroying to do.

Painkiller's structure is actually a little different to what we have become accustomed to with modern, more narrative-heavy first-person shooters. Each level is made up of a sequence of closed-off "arenas" where swarms of enemies pour in in their hundreds, and it is Daniel's job to dispatch them, then repeat until he reaches one of the enormous and visually impressive boss monsters, at which point it comes down to an epic battle to the death. In this sense, despite being having full freedom of movement, Painkiller at times feels akin to playing something like House of the Dead, with scripted waves of enemies attacking from all angles and the player having to respond quickly. It's certainly incredibly exciting, particularly with the thrashing metal soundtrack that blares away during battle.

And what monsters! Playing Painkiller, you'd be forgiven for assuming the developers took a list of "cool monsters" and a list of "cool places" and just picked one from each list for every level. To whit, one level sees you fighting ninjas in an opera house, for no discernible reason that benefits the story other than the fact that it's awesome. Another has you battling a gigantic ogre in a cathedral. Yet another sees you fighting exploding cyborg mental patients in a lunatic asylum. If they'd included pirates in space, all avenues of awesomeness would be comprehensively covered.