Don't let the dark setting put you off this awesome action horror title.
Doom 3 has brought the game back to its begining (Doom 1) but this time tells the story in greater detail with a sort of survival horror twist. Scientist messing around with teleportation technology and traveling to an alternate realms (which happens to look alot like hell) to collect samples, have taken something they shouldn't which unleashes all hell, Literally (when will scientist in games learn not to mess with teleportation).
This is where you come into the picture. As a lone marine it is up to you to send these abominations back to hell you will be required to perform the usual FPS tasks like reactivate the power so the lift will work to get the keycard to the next room. Along the way you will be running down dark corridors with zombies and other hellish creatures ready to jump out of the dark to scare you. The first half of the game is full of this erie sense that something is going to jump out at every corner but it later turns into a full on action FPS especially when you go to hell which requires you to pick the right weapon for the situation and by this time you have them all.
I will admit that I didn't like it a first but once I knucked down and played it properly and became immune to the horror the monsters never knew what hit them.