Doom 3 Introductions

Doom 3
You are a marine, one of Earth's toughest, hardened in combat and trained for action. Shortly after reporting for duty at the Union Aerospace Corporation's Mars research facility, a massive demonic invasion overwhelms the base, leaving chaos, horror and uncertainty in its wake. As one of only a few survivors, you must use overwhelming firepower and all of your combat skill to battle through the demon hordes, find out what went wrong and prevent the evil from spreading. Only you stand between Hell and Earth.

Resurrection of Evil
It has been almost two years since the mysterious incident shut down the UAC base on Mars. Several months ago, one of the UAC satellites still monitoring the red planet detected a beacon originating from Site 1. This early research facility was long forgotten, even before the invasion. Now. you're a Marine combat engineer, part of a massive research and security team lead by Dr. Elizabeth McNeil. Your team is being sent back to Mars in an attempt to find and investigate the source of this strange signal. What you'll find, nobody knows, but hopefully it will offer new insight into the ancient civilization that once inhabited Mars.

As your transport nears the surface, you cannot help but wonder what type of "accident" could have killed so many two years ago... and could it happen again?