Playing this on a 5.1 surround sound in the dark is an intense experience that, if possible, must be enjoyed. Even Far Cry's impressive vistas and wonderful environments can't stand up to the artistic and technical might of this sensory feast.
DOOM 3 is extremely immersive with about as perfect a presentation as I've ever seen in a game.
Not necessarily for the gameplay aspects, but for the fact that my eyes and ears never went a moment without being completely entertained.