The Precursor Race was a highly advanced, ancient, space-faring alien race that arrived on Planet 4546B approximately one thousand years ago, searching for a cure for the Kharaa Bacterium. Most information surrounding them is currently unknown, other than the fact that they lived for an extremely long time, shown in data bank entries by the mention of a ninety-six year old Precursor being extremely young. It is likely that they were a lot larger than humans, based on the size of their bases and the objects within them, a prime example being the height of the surgical tables found in the Disease Research Facility. The use of the word "seed" in reference to the unborn form of a Precursor possibly implies plant-like biology, though it is equally possible that seed could refer to an animal ovum.
Their ulterior motive is to stop the spread of the Kharaa Bacterium, a bacterium that they discovered which currently ravages Planet 4546B and seems to have caused the extinction of the Precursor Race. To accomplish this, four facilities were set up on the Planet, each serving its own purpose.
Although the Precursors are not seen in-game, they were an extremely advanced race - able to create advanced technology (such as teleportation devices, weapons capable of bringing down large ships, wirelessly powered biomechanical life forms capable teleporting at will, of etc.) and the technology to capture a Sea Emperor Leviathan. They are also capable of creating Data Hubs, which they can upload their mind to, the digital equivalent of a medically-induced coma.
Not much is known about their abilities, however, the Precursors are able to create and use Warpers as guards for their bases and use them to hunt down creatures infected with the Kharaa Bacterium, and create technologies far more advanced than humanity's current technological state, and at the same time, predating humans by thousands of years. It has also been shown in data downloads that the Precursors were able to transfer their consciousness to computers, where it could be stored for an indefinite amount of time, at least one Precursor transferred itself to a data hub in one of the Alien Caches. The Precursors are also able to create "keys", known as Alien Tablets, which unlock various things, including forcefields and Alien Arches, which function as teleporters. In addition, they can create alloys that are highly heat-resistant and can last over one thousand years with no sign of degradation. The Precursors also created the Alien Robots that repair and, if need be, defend the Alien Bases from intruders. Despite having their own form of telepathy, the Sea Emperor Leviathan suggests that the Precursors were not able to hear its voice.
The Precursors came to Planet 4546B around one thousand years ago in their search to find a cure for the Kharaa Bacterium. They built four bases on the planet, the Quarantine Enforcement Platform, the Disease Research Facility, the Alien Thermal Plant and the Primary Containment Facility.
Each of these bases serves a different purpose in the fight against the Kharaa Bacterium. The planet was set up so that if the bacterium was ever released by accident, the whole planet could be quarantined, allowing no ships to enter or leave the planet. In order to enforce this, the Quarantine Enforcement Platform and Self-Warping Quarantine Enforcer Units (Warpers) were created.
The Quarantine Enforcement Platform (QEP) fires an energy beam at any unauthorized ship that tries to enter or leave the planet, severely damaging or even completely destroying the vessel. The Warpers are cyborgs, created through combining the body of an already existing creature with Precursor technology (more details on Warper page), capable of phase jumping at will and powered wirelessly by the Precursor Thermal Power Generator - they will attack and attempt to kill any Fauna infected with the Kharaa Bacterium. This base is responsible for causing the Degasi and Aurora to crash, as well as destroying the Sunbeam during its attempt to rescue the Player.
The Disease Research Facility (DRF) was a lab dedicated to researching the effects of the Kharaa Bacterium on living specimens. At some point, a Sea Dragon Leviathan that was attempting to retrieve its egg which was contained within the structure destroyed to the facility, causing the Kharaa Bacterium to be released into the water. This had catastrophic effects on the planet, with many species dying because of it. The planetary quarantine was put into effect as a result.
The Alien Thermal Plant (ATP) located in the Lava Castle seems to be the power source for all of the Precursor technology on the planet. 30% of the power generated is stored for emergency use, 30% supplies the Ground-To-Air Weapon System with energy, 22% goes to the Primary Containment Facility, 11% goes to the Disease Research Facility, and 7% runs the Self-Warping Quarantine Enforcer Units (Warpers) wirelessly. It is the smallest of the four alien bases.
The Primary Containment Facility (PCF) is located in the Lava Lakes, the deepest biome on the planet. The main purpose of this base is to develop a cure for the bacterium by using the last surviving Sea Emperor Leviathan, and its five eggs. The Sea Emperor Leviathan contained in this base is immune to the Kharaa Bacterium due to it producing quantities of Enzyme 42. This enzyme is a vital ingredient to curing the Kharaa Bacterium. The five remaining eggs of the Sea Emperor Leviathan are dormant. They are being kept alive by the Incubator Device. The eggs require specific conditions in order to hatch, as such they have been in a state of stasis for hundreds of years. These eggs must be hatched at some point in the story. A sample must be taken from the Sea Emperor Babies to cure the player of the Kharaa Bacterium. This facility also features four warp-gates to different biomes on the planet.
- The player may be able to craft warp gates rooms using Precursor Ion Cubes and Warper technology.
- Various Data Downloads suggest that the Precursors may be capable of some form of telepathy.
- The ancient Mongolian blade found in the antechamber of the Primary Containment Facility suggest that the Precursors visited Earth in the past. The Alien Carving also supports this theory, as the yin and yang symbol was a major part of ancient chinese philosophy. 
- ↑ http://imgur.com/a/igILF
- ↑ https://trello.com/c/d5EIBbi9/174-buildable-teleporter-room Dated August 25th, 2016.
- ↑ https://trello.com/c/n1OdLQqq/6129-generate-precursor-artifact-ideas-for-prison#action-58921c71d42a44df8b3298e7