Painkiller

Tremendously fun shooter of the, now, old-school variety. I think this one was notable because this is when physics were first being implemented in games and I remember having a ton of fun with perhaps the best weapon in the game: the stake gun. If you shot an enemy with it they'd instantly be flung and pegged to a wall-- dead instantly. Amazing.

Other than that I'd say it was a shooter in the vein of Doom. Quite fast paced with plenty of demons to murder or be murdered by. Quite a fun romp!