Vault Zero (location)

"Alain: What is this place? I don't think we're supposed to be down here.” “Athena: This is Vault Zero. From what I hear, it belongs to Eclipse Research Laboratories. And Ronin came down here so we have no choice!” “Alain: Vault Zero? I thought this was a myth?” “Athena: Its very much real, Alain. The only reason we think that is because Research Laboratories has killed anyone who attempted to reveal it. Wouldn't be surprised if we become part of their hit list after they find out we were here.” “Alain: Well, they wouldn't do that, would they? I mean, we assisted in ending the Conflict and Barstow personally commended us.” “Athena: Barstow is just a man who's been destroying the Federation from the inside."

- Alain & Athena

Vault Zero is a highly classified black operations facility operated by Eclipse Research Laboratories, a branch of the Eclipse Military responsible for the acquisition, development, research, and concealment of all entities, items, artifacts and weapons deemed "out of universe" and extremely dangerous by a team of high ranking officers within Eclipse Army Command. It is located on Luna, the Eclipse Navy's fortress facility and its main headquarters, protected by the largest fleet of warships in the Navy.

Purpose
According to Alliance Forces Technical Sergeant Athena, the facility's existence and location is protected by Eclipse Research Laboratories, killing all those who have threaten or attempted to reveal its existence and location to the Eclipse Military, specifically High Command and the Presidency Council.

As such, Vault Zero is where Research Laboratories stores "out of universe" entities, items, artifacts and weapons in order to both research and study them as well as keeping them concealed from the outside galaxy to prevent them from falling into enemy hands.

Vault Zero
Despite the facility's secrecy, Master Ronin led a campaign against the Eclipse Federation in pursuit of the Matter Orb and found out it was stored at Vault Zero, Eclipse Research Laboratories' highly classified facility on Luna. In order to have gained access to the Vault, Ronin replicated warships at the Red Tern Shipyards where he went to Luna posing as the reaction response fleet sent to Red Tern.

There, he ordered the warships under his control to attack the Luna Defense Fleet as a distraction in order to access Vault Zero and secure the Matter Orb. However, he is stopped by Athena and her team, and is told to surrender. Not wanting to give up the Orb, he orders his robotic forces to distract them while he goes to secure it. After his forces are taken care of by Athena, Alain, Jack, and Ben, they are unable to stop Ronin who now possesses the Orb. However, the Luna Defense Fleet is able to hold back against his replicated warships and regain control of Vault Zero, activating its lockdown protocols, trapping all of the undead within.

Ronin then uses the Orb to send out a shockwave of dark energy and knocks down everyone around him, allowing him to successfully escape Vault Zero and retreats back to his flagship. However, Athena says they cannot let Ronin escape and follow behind him, using a ship and boarded his flagship before it enters slip-space to an unknown location.

Aftermath
In the aftermath of the battle, Eclipse Research Laboratories' Security forces as well as personnel from the Zombie Extermination Force, led by Alain, begin to cleanse Vault Zero, however Research Laboratories captures some of the undead as specimens for further research and study, possibly in order to weaponize them for the Eclipse Military.

Checking CCTV security footage in order to make sure everyone involved during the battle were killed by the undead forces, they spot Athena, Alain, Jack and Ben; all of whom were not part of the pile of dead bodies they gathered. In response, the Army Command officers in charge of Vault Zero and Research Laboratories blacklist the four "heroes" for execution/assassination.