Our very existence is in grave danger. Inside resources have notified us that the Pfhors have developed the means to time travel. They have also told us that they have sent forces to Earth sometime in the late 20th century. Their objective is clear: destroy the Marathon project (then a top secret government organization) at its inception. We have managed to acquire, through various spy channels, roughly 80% of the technology used in the Pfhor's time travel device. A makeshift machine is being constructed as you read this. You have been awakened to once again serve your purpose. Grab your issued pistol and report immediately to chamber B for preparation to travel back to earth.
-By this time all your sensory functions should be operating within acceptable tolerances. -More and more information is coming in, and we have narrowed the Pfhor's destination date to March 13th, 1984 and the location to "Marathon Campus", on Earth. The navigation sensors of this machine are a little tricky, but it appears to read that the Pfhor have infiltrated the campus through the sewer and power complex below the surface.
Your Instructions are as follows: -Eliminate all enemy presence in the sewer and power complex. -Reach the surface -Locate Marathon headquarters. -Once you find the headquarters, we will teleport you an access card allowing you to enter the HQ complex. -Finally, eliminate all enemy presence on Earth.
It is worth noting that the BOEs (Born On Earth) may consider you a hostile threat. Engaging the humans may be necessary until they realize your allegiance to their cause. Due to technical uncertanties, only one marine can be transported, and only a limited amount of ammunition will make it to Earth. We will send supplies when we can, but take advantage of the fallen BOEs' ammunition supplies to augment your own. Good luck, Marine! Civilization as we know it is depending on you.
Addendum: In 1984, scientists working for the Marathon project were experimenting with pattern buffers. Locate and use at your own risk. Information terminals were also scarce; we will attempt correspondence as the opportunities arise.