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Infestation is the foundational game mechanic of the Alien team responsible for territory expansion. It is a large, Algae-like mass that spreads across floors and onto walls.


All Alien Commander abilities and Commander-built Structures with the exception of the Hive must be placed directly on Infestation.

The primary method of creating Infestation is by the Alien Commander placing Cysts across the map in a chain originating at a Hive, known as 'Cysting' (see below). This chain must be kept intact and any breaks in this chain will cause Cysts at the end to die and the Infestation they have created to recede.

Unlike Marine structures that can be placed anywhere on the map, Alien structures must be placed on infestation and 'grown' to completion. This means that an Alien team can be typically much slower to expand than a Marine team.


A prospective Alien Commander should learn how to Cyst the map economically and defensively. Placing Cysts out in the open will usually always result in them being destroyed, therefore it is wise to utilise props and different elements of the map to 'hide' Cysts.

The game will assist the Commander by automatically placing the minimal amount of Cysts required to form a functioning chain, if a Commander places a Cyst directly at a distant point on the map. However, this will result in Cysts being placed in tactically poor locations so should be avoided in areas likely to see extended conflict.


All Alien structures that do not generate infestation require infestation to survive and take damage until death whilst off infestation.

Infestation Source

These structures generate infestation:

without Infestation

The following structures survive without infestation:

All other Structures will take 30 (Corrosion) damage per second off infestation.

It takes 60 seconds to die off infestation, except the Harvester which takes 90 seconds.


Infestation is corrosive to Marine structures

  • 15 damage per second against the Armor of Marine Structures and ARCs (and kills Mines).
  • 25% slower building of Marine blueprints
  • Invisible if a nearby Shade is cloaking the Cyst. (If the Cyst is only cloaked because of a Shade Hive then the Infestation stays visible.)

Minimal Infestation

Main Article: Graphic Options

With the Graphic Setting Infestation you can change between rich and minimal Infestation. Currently rich has a high CPU usage and obstructs the view of the player quite a bit.


In Subnautica (another game developed by Unknown Worlds), the bacterium Kharaa was released by the Architects due to an incident at the facility they were using to research the Kharaa, resulting in the Quarantine Enforcement Platform being activated to prevent incoming or outgoing travel from 4546B; the main events of Subnautica revolve around the player finding a cure for the Kharaa, which they eventually succeed in, spreading the cure everywhere throughout the planet. The Kharaa of Subnautica is distinctly different in that the bacteria's blisters are green rather than orange; the developers confirmed that the Kharaa in Natural Selection is a mutated form of the Kharaa in Subnautica.