Doom 3: Phobos

You wake up inside a repurposed apartment in Mars City. You do not recall how you got there or any specifics about your person. You soon meet Samantha Miles, an agent of a sketchy world-wide conglomerate, who claims to know you. While she helps you with your identity, you aide her in the quest to find a long lost friend and missing agent. When the original events of Doom 3 unfold, the two of you must scramble for safety while still tracking down the missing agent and your identity.