In the distant future, the human race has fallen to its knees after an unknown alien race invades earth, which results in the enslavement of the population. This occurred due to the development of long-range portals, which resulted in the aliens discovering the location of earth. You are the marine, a high-tech soldier sent to locate a time machine which can alter the course of history, for the better. The Marine lands on Earth in a Life-Capsule, then makes his way to the Time Machine, fighting any alien, Human or Android that is hostile to him. Proxy, an enemy of Civil Security, escapes from the security and goes outside, only to see the security troops outnumbered against the Usurpation Soldiers, who are teleporting into the base. She joins the Marine on his journey, after running into him, but is unaware that he is one of the two volunteers that used the Time Machine. Noir Lime crashes into the building that the Marine and Proxy have just entered, and although he arrives dead, he is in better condition than when the Marine left him. He tells them that the Time Machine is in the building, and the three fight their way through Civil Security Bosses, Usurpation Destroyers and Corvettes to reach and activate the time machine. Just before the volunteers use the Time Machine, Noir Lime shouts "Forward to the past!" In the final assault, an android escape from a cave filled with Civil Security Ghosts.