"The level design and lack of lighting is used to create the fearful atmosphere, part of it is psychological, generated by the hostile environment, and your willingness to survive where all others have been hideously killed.

Instead of security cards like in the original doom to access locked rooms, you carry a PDA which stores all new security clearances, maintains a log of emails, voice, and video discs, and gives you access codes to 30 locked storage cabinets that contain health, weapons, and ammo.

As you go through the game, audio logs push the think storyline along. Often you encounter the horrific bloody remains of the person who recorded the log listening to their concerns and fears at times amusing ramblings."