The game begins with a strange phenomenon in which another Earth appears in our skies. The curiosity and fear of a doppelganger planet initiates multiple missions in order to make contact with the duplicate Earth. A team of agents, astronauts, and scientists were sent 955,600 miles across space by NASA and the US Military, however all contact is lost a few hours after their arrival. You play as a marine named "Jake" who is sent on a mission to retrieve any research and data left behind by the original survey team while fighting off hostile forces. As Jake, you must traverse the zombie-ridden lands of the alternate Earth as you battle endless hordes of the undead, frightening mutants and insane soldiers. While you collect recordings and research papers you will steadily come upon the horrifying revelation that lead to the parallel Earth's demise.