id Software announces the development of Doom 3, generating early excitement in the gaming community.
The expansion pack for Doom 3, titled Resurrection of Evil, is released, adding new content and gameplay features.
The Doom 3 BFG Edition, a remastered version of the game with enhanced graphics and additional content, is released.
The Union Aerospace Corporation (UAC) begins construction of the Mars Research Facility to study and experiment with teleportation technology.
UAC researchers discover ancient artifacts on Mars that indicate the presence of an ancient civilization and a gateway to another dimension.
UAC starts teleportation experiments attempting to access other dimensions using the discovered artifacts.
The teleportation experiments go awry, opening a portal that allows demons to invade the UAC Mars Facility causing widespread havoc.
The protagonist, a UAC marine, arrives at the Mars Research Facility amidst the outbreak to investigate and contain the disaster.
Attempts to contain the demonic outbreak fail, leading to the spread of creatures throughout the facility and creating chaos.
Due to continued experimentation, the Hell Portal fully opens, allowing massive numbers of demons to pour into the Mars facility.
The UAC marine must navigate through the facility, battling demons and eventually shutting down the portal to Hell to stop the invasion.
The marine confronts the source of the invasion, defeating the ultimate demonic forces and successfully closing the Hell Portal.
