The Human civilization founded a new galaxy around 2295, about 100 lightyears away from their own planet, known as "Earth." It had repaired itself from the disaster it had once had in 1945 and again in 1965, with multiple zombie outbreaks, due to Element 115. Around 2289, American scientists had collaborated with Russian and Chinese scientists in studying Element 115 further. However, it was suggested that they move to a new planet for further examination. It took the Human civilizations a good 10 years to develop light travel, and they had found a new galaxy, naming it "Xenon." The scientists went to a small, solidified planet in the heart of the galaxy, naming it Xenon 115. However, around 60 to 70 years later, the Element 115 project had gotten out of hand and the zombies had gone insane once more. Four brave soldiers were chosen to try and handle the situation as best as they could.
Terra 4 (Main Group)
Oriel-Niner (Side Group)
Indentation indicates that it is merely a side mission/minor location.