As Daniel Garner, stuck between heaven and hell you get to kill an overwhelming amount of demons and monsters in this game as you scrounge through level after level of killing enemies incessantly with powerful weapons.
Each level throws tons of enemies at you and you can practically color the room red with the limbs of the dead. The monstrous boss fights at the end of each level are a gory fun and a delight to awe at. The scale is pretty impressive in those fights.
Painkiller is a no non sense FPS that does best what it tries. The difference between Doom 3 & this one is that Doom 3 tries to scare you in the dark whereas this game just throws a bunch of demons for you to deal with. The game levels are uniquely designed and the metal thrashing music that plays around is quite involving.
In all, its a gory ride between heaven and hell. Make sure you don't miss it.