The Alien Machine or the Alien City is the conduit of the Codex, created by the unidentified race of aliens who inhabited Tau Volantis. Located beneath a huge mountain overlooking the abandoned Sovereign Colonies' research base, the city-esque machine houses the corpses of the deceased species and their Necromorph counterparts.
The massive structure of the machine is a maze of paths and catacombs surrounded by pillars that lead to the control center for the Codex. The bodies of the aliens themselves appear to be one with the machine, standing erect or hunched over the pathways leading to the conduit, their arms and legs seemingly fused with the stone like structures they're pressed against.
Special platforms that amplify the use of kinesis and stasis are scattered throughout the machine and are particularly situated before doors that require the decryption of the modified language used by the aliens to bar or allow entrance to certain areas. The "promenade" in particular is an area surrounded by an arch; situated before large doors and monoliths that require the manipulation to successfully activate the kinesis boost that will launch the traveler across great distances in a short amount of time. Opening all pathways allows easier access to the machine.
Eroded by the passage of time, when the city is rediscovered by the Sovereign Colonies in 2311, its pathways are obstructed by thick and sticky webbing, the possible remains of the Corruption created by the Necromorph life form. Years later, in 2514, remnants of the deep dig team's work, scaffolding, construction material and generators, still remain scattered throughout the massive structure, a sign of their incomplete work.
After the Convergence Event that wiped out the aliens, the Machine was hidden underneath a huge mountain. The Sovereign Colonies set up a huge base right underneath the mountain as well as on top of the mountain peak. A huge wall was set up around the perimeter. A lift system was built on the mountain side to allow travel between the mountain and the colony below, as well as an underground "tram" system to allow an easy and quick travel of men and supplies. However, as the cleanse order was executed, the base was abandoned with the lifts and tram system cut off, until 2514.
Events of 2314 and 2514 Edit
In a move to prevent the completion of the Convergence Event triggered by the Markers, the aliens constructed the machine and a Codex that would freeze the planet and pull the moon down onto Tau Volantis killing it. For whatever reason (presumably Necromorphs) they never completed the machine, so they created a language that could be utilized by a future species in event of discovery, warning them of the danger and how to complete the machine when found.
Some two million years later, in 2311, the Sovereign Colonies Armed Forces discovered the planet by triangulating the signal perpetuated by their own Markers. Research teams led by Dr. Earl Serrano found their way into the underground of the frozen and seemingly barren planet; there they found the frozen corpses of the aliens within their city. In awe at their sheer size and majesty, the researchers then explored the city and discovered a wealth of artifacts. Little by little, the more Markers and lifeforms they unearthed, the closer to the truth they became.
Eventually, Earl Serrano figured out what happened on the planet and tried to finish what the aliens started when they halted Convergence. Unfortunately, the spread of the Necromorph life form, using the bodies of their fallen soldiers and researchers, complicated the situation. His efforts were largely thwarted by General Spencer Mahad and the "Scenario Five" order which entailed the eradication of all personnel and the destruction of all information on the aliens, including the Codex. The planet and the Sovereign Colonies expedition remained lost to history for the next two hundred years before the accidental rediscovery of old SCAF information in 2514, by Marker researcher Damara Carver on Uxor.
Ellie Langford, a friend of Damara, sought to complete the doctor's work and, with help of Robert Norton and Damara's husband, John, initiated the journey to the planet to stop the spread of the Necromorphs. When Isaac Clarke is brought out of hiding, Langford's efforts to reach the planet are largely successful through his understanding of Marker script, thinking Tau Volantis is the marker home world. Hounded by the Unitologists led by Jacob Danik who want to stop them, they race to piece together the broken information left behind by Serrano. They learn what the late scientist did two hundred years ago and from there, they rebuild a Codex from the memories of Rosetta.
Though Isaac and Carver venture into the heart of the machine to stop Danik from restarting the Convergence Event, the Unitologist uses the Codex to free the Moon from hibernation, which triggers Convergence, the moon proceeds to tear apart the machine and the mountain. Battling the massive Necromorph, Isaac and Carver eventually manage to disable the creature long enough to reactivate the machine with the Codex and destroy the Moon. Their efforts result in the halt of the Moon's signal altogether.
- The Machine may be a massive kinesis and stasis structure. That would explain how Isaac and Carver were capable of surviving the fall back to Tau Volantis. It may also explain how the machine managed to freeze the planet, and pull something the size of a moon onto Tau Volantis.