From ebgames.com:

DOOM 3 - id Software's terrifying battle with the forces of Hell. A massive demonic invasion has overwhelmed the Union Aerospace Corporations' (UAC) Mars Research Facility leaving only chaos and horror in its wake. As one of only a few survivors, you struggle with shock and fear as you fight your way to Hell and back, in an epic clash against pure evil. Built on id's revolutionary new 3D graphics engine, DOOM 3 draws you into the most frightening and gripping 3D gaming experience ever created.