Doom is a first-person, survival, horror game developed by ID Software. With the objective being surviving battles with demons, it is set in the year 2145 on the planet Mars, where a series of experiments (e.g. teleportation) are taking place. However, these experiments have led to the opening of a portal to the kingdom of hell being opened, leaving the protagonist having to fight against demons.

The emphasis is on the horror aspect of the game. For instance, in 'dark' mode, the player has to choose between holding a lantern and holding a weapon. Over the intercom one can hear horrifying sounds, such as screams, heavy breathing, someone dying, and other unexplained noises. The aim is to win battles against zombies (possessed humans) and demons.

Each user is furnished with a personal data assistant (PDA) on which emails and other communications can be sent. The point to note is that when a user picks up any discarded PDA, all the information on it is immediately downloaded onto his PDA. The game is set on the planet Mars (in the year 2145), and because of this location the staff of UAC (Union Aerospace Corporation) are free from legal and ethical restrictions. However, staff have become very concerned at the symptoms of the experiments, which include the hearing of voices and the loss of sanity.

You are the protagonist, fighting against these demons. Your non-commissioned officer is a Thomas Kelly, from whom you receive orders and objectives. Your protagonist is a Malcolm Betruger, head of a division called Delta of UAC. He is responsible for the experiments that are occurring on the UAC plant on Mars, and to top it off he has a demonic voice.