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Alien Concept Art


The Kharaa and the subspecies that make up its hostile presence on various human installations are the product of a previously unknown Bacteria-like growth that rapidly evolves and directly sets in motion the events that lead up to the hostile encounters with humans, and was accordingly termed by TSF scientists as Bacterium. The Bacterium is the basic building block of the Kharaa, and is responsible for the evolution and aggressive behavior of the Kharaa lifeforms. The creatures and structures that the Kharaa have at their disposal were previously not associated with the Bacterium whatsoever, but were separate species that were infested and incorporated into the Kharaa gene pool (including structures such as the Harvester). Once assimilated, these species would be regularly reproduced, albeit re-purposed to better suit their role in the Kharaa, such as carapace and the razor sharp blades that Skulks and Fades evolved.

The terminology for the aliens is still being developed. At the moment, we refer to the aliens, and their whole system of bacteria, lifeforms and growths, as the "Kharaa"; and the pre hive-stage presence as the "bacterium". The first TSF encounter with the aliens occurred aboard the Mongol's Sanjii mining facility. The tattered voice comm logs they extracted from the command network had one word that stood out, used again and again – "Kharaa!" "Kharaa!" Later, it was understood that this means "Watch out!" in Mongolian. By then, it had stuck.

The Kharaa began appearing on ships and bases throughout the Ariadne Arm a decade ago, slaughtering everyone on board. In almost every case the ship then wandered off course, and either destroyed itself by slipping into some gravity well (usually a planet or sun), or was tracked down and destroyed by the owners of the craft. Life support on bases and ships usually fails soon after the Kharaa take over, so even without military response, they don't last very long. However it is still unknown how their appearances on numerous ships and installations can be prevented, and until more conclusive information can be gathered by scientists, humans may never know how or why the Bacterium is capable of setting forth such a destructive onslaught without any early indication or warning.

Initially, the Bacterium only reproduces, slowly forming a mat, visible to the naked eye. All of these bacteria are in contact with one another, sharing data on their environment, and triggering responses to stimuli (like energy sources, or danger). They form a network that links all Kharaa lifeforms and structures, and is responsible for the phenomenon of Hive Sight. It isn't until the presence of larger lifeforms that the next stage of alien growth, the Hive, begins. The hive contains all the information and abilities necessary to set off a cascade of events that rapidly leads to full scale conflict. Like all the other Kharaa structures, TSF scientists speculate that hives are actually creatures that have been evolved into this form over an incredibly long time, and have observed that Kharaa structures in general tend to resemble aquatic forms of life, contrary to the Kharaa lifeforms that clearly originated from mammals and other similar creatures.

The bacterium seems capable of tapping a wide variety of energy sources. Heat and water are diverse enough, but it also finds the rich sludge used for nano-construction highly desirable. Fortunately the same safe guards that prevent marines from automatically accessing these stores thwart the Kharaa too. Unfortunately, the aliens seem quite prepared for this sort of obstacle, building Harvesters atop resource nodes, that draw the sludge up and digest it. These chambers appear to have once been a species, much like the hive. What these resource chambers could have been used for before the Kharaa encountered us is a perplexing mystery. But they convert the sludge into a usable form, just as our resource towers do. As a result, marines and Kharaa end up fighting for the same resources. Defending these resources is vital to the Kharaa, second only to protecting their hives.

To destroy the human presence, the bacterium employs lifeforms of its own. These are the creatures that slaughter the crew of the ship or base, and the same creatures that are waiting for the Frontiersmen when they arrive to take the ship or base back. Kharaa species have natural weaponry and cunning that make them a match for the best equipped and most highly trained forces the TSF can deploy. Hives continue to spawn lifeforms over the course of a conflict, replacing lost aliens. Destroying all hives is the only way to cease the everlasting onslaught.


The Kharaa life cycle begins with the Egg, which is commonly found in large clusters around a Hive. The basic form of the Kharaa, the Skulk, hatches from an egg by biting through the membrane. It has been observed that when the threat to Kharaa territory becomes formidable, the aliens respond by evolving into different and stronger lifeforms as the situation demands. These lifeforms are classified as the Gorge, Lerk, Fade, and Onos, each with their own unique abilities and roles to fulfill.

Kharaa lifeforms are capable of communication through Hive Sight, an instinctive visual mechanism that allows them to identify friend from foe. The Kharaa also possess enhanced senses, more notably Alien Vision which grant perfect visibility in darkness.

Kharaa Lifeforms
Lifeform Abilities Description
Slot Alternate Movement

Skulk idle.gif


Bite slot.gif

Leap slot.gif

Sneak slot.gif

Basic lifeform that climbs walls to disorient and ambush prey.
Parasite slot.gif

Xenocide slot.gif


Gorge idle.gif


Spit slot.gif

Heal spray slot.gif

Heal Spray
Belly slide slot.gif

Belly Slide
Support lifeform that acts as healer, builder, and demolisher.
Gorge build menu slot.gif

Build Menu
Bile bomb slot.gif

Bile Bomb
Babbler bait slot.gif

Babbler Bait

Lerk idle.gif


Bite slot.gif

Poison Bite
Spikes slot.gif

Roost slot.gif

Flying lifeform that excels at dealing damage over time.
Umbra slot.gif

Spores slot.gif


Fade idle.gif


Swipe slot.gif

Blink slot.gif

Elusive lifeform that specializes in assassination and escape.

Stab slot.gif


Onos idle.gif


Gore slot.gif

Stomp slot.gif

Charge slot.gif

Gigantic lifeform that absorbs damage and demolishes structures.
Bone shield slot.gif

Bone Shield


Evolutions (or Traits) are purchased upgrades that passively enhance Kharaa lifeforms' defensive, deceptive, or reactive capabilities. The Hive can evolve into different types to unlock evolution structures: Crag Hive (Shell), Shade Hive (Veil), and Shift Hive (Spur). Traits are accessed in the Evolve Menu, and will cost Personal Resources depending on different lifeforms. Only one of two traits from the same evolution structure can be evolved by players, but they may switch traits any time with enough Personal Resources.

If all evolution structures are destroyed, the pair of unlocked traits will lose all effects and become inaccessible to players. However, players that already evolved a trait will retain their purchase and regain the trait's effects when the associated evolution structure is rebuilt.

Prerequisite Trait Description Additional Information




Increases total Armor pool depending on lifeform.
  • Armor bonus increases with number of existing Shells (maximum 3 levels).


Increases passive Health/Armor regen by 6% of max health/armor per 2 seconds (80HP Max.)
  • Regen bonus increases with number of existing Shells (maximum 3 levels).




Reveals nearby Marines and Exosuits' presence and indicates their health by colored icon.
  • Reveal range increases with number of existing Veils (maximum 3 levels).


Renders the lifeform invisible based on tier level, even while moving.
  • Each Spur increases the effect of the cloak when standing still and moving (Maximum 3 Levels).




Increases total energy pool and recharge rate by 10%.
  • Energy pool and recharge rate bonuses increase with number of existing Spurs (maximum 3 levels).


Increases move speed by 0.5 meters per second.
  • Move speed bonus increases with number of existing Spurs (maximum 3 levels).

Commander Abilities

The Alien Commander is a hive mind presence that governs over Kharaa territory and evolution. It aids in coordinating lifeforms, spreading the Kharaa Infestation, and growing various organic structures. Any lifeform can enter an unoccupied Hive to act as Alien Commander, which changes the player's perspective from first-person to an overview of the map. Only one Commander can be active at a time, and he may exit the occupied Hive to become his previous lifeform.

The Commander has a user-interface that includes a Mini-map, commander menu, and resource counter, allowing him to build structures and perform upgrades for the Kharaa. He can also assist his lifeforms using various abilities at his disposal; commander abilities cost Team Resources and are mostly found in the Assist tab, with some requiring the presence of specific units and structures to trigger.

Alien Commander Abilities
Assist Tab Drifter
Heal wave icon.gif Ink icon.gif Echo icon.gif Enzyme cloud icon.gif Hallucination cloud icon.gif Mucous membrane icon.gif
Heal Wave Ink Echo Enzyme Cloud Hallucination Cloud Mucous Membrane
Nutrient mist icon.gif Rupture icon.gif Bone wall icon.gif Contamination icon.gif
Nutrient Mist Rupture Bone Wall Contamination
  • Heal Wave, Ink, and Echo require a nearby Crag, Shade, or Shift to activate.
    • Requires Crag/Shade/Shift Hive types to unlock.
  • Nutrient Mist, Rupture, and Bone Wall can be used anywhere on Infestation.
    • Requires Biomass levels 1 to 3 to unlock.
  • Contamination can be placed anywhere on the map.
    • Requires Biomass level 9 (see below).
  • Enzyme Cloud, Hallucination Cloud, and Mucous Membrane require Shift/Shade/Crag Hive types to unlock.


Biomass is a tech progression system that serves two functions: increase all lifeforms' maximum Health pool and enable unlocked lifeform abilities after research from the Hive. Each Hive can contain up to 3 Biomass levels; 1 level for being an active Hive and 2 additional levels can be upgraded by the Alien Commander.


The Infestation is a green moss-like collective mass of billions of microscopic Bacterium. It grows outward from the Cyst, Hive, Gorge Tunnel, and Contamination structures, and is essential to Kharaa territory expansion. The Alien Commander can sprout any Kharaa structure directly from the Infestation itself.

Most Kharaa structures require Infestation to survive, except the source structures which produce the organic substance. Infestation is also sustained by the source structures, as otherwise the Infestation will dissolve rapidly into nothing with its source destroyed. Infestation possess corrosive properties that damage Frontiersmen structures' Armor, along with the sticky mass that slows down blueprint construction when in contact.


All Kharaa structures will automatically undergo a growth process known as Maturation. A newly grown structure is low on Health and Armor, but as the structure ages, it will reach its strongest state. The Alien Commander can use Nutrient Mist to rapidly age structures even in their unbuilt state.

Units and Structures

Units and structures are placed by the Gorge and the Hive specifically. Buildings that are placed by the Gorge are taken from the players own Personal Resources and the structures placed by the Alien Commander are taken from the Team Resources.

Player Built Structures

Gorge Structures
Owner Structure Description Shared Attributes Additional Information
90px-Gorge kharaa main.PNG

Hydra spawn small.gif

Small static turret that detects Marine presence and shoots spikes at Frontiersmen units and structures.
  • Can stick onto walls, ceilings, and Clogs.
  • Auto-builds at 70% build rate without Grow or Heal Spray.
  • Vulnerable to fire from Welder, Cluster Grenades, and Flamethrower.
  • Digestible by owner to remove from play.
  • Destroys oldest structure when new one is placed and limit is reached.
  • Grows when on Infestation, but requires Heal Spray when on uninfested ground.
  • Cannot attack when on fire.
  • Maximum 3 per player.
Clog idle small.gif

Organic blob that can act as blockade and absorbs all types of damage.
  • Instant build time.
  • Resistant against high burst damage such as Grenade Launcher explosions.
    • Cannot be healed.
  • Maximum 10 per player.
    • Digestible by both owner and friendly players to remove from play.
Babbler egg grow small.gif

Babbler Egg
Babbler hatch small.gif

Babbler Egg - Oval-shaped egg that grows and hatches into 3 Babblers.

Babbler - Small critters that follow their owner everywhere and attack any Frontiersmen units and structures on sight.
  • Can be placed on uninfested ground.
  • Auto-builds at 70% build rate without Grow or Heal Spray.
  • Can stick onto walls and ceilings.
  • Babblers are attracted to owner's Babbler Bait and will cling to friendly lifeforms to absorb damage.
    • Babblers are always visible to the owner through Hive Sight.
  • Requires Biomass level 1 and Upgrade Gorge from the Hive.
  • Maximum 3 per player (9 Babblers total).
    • Destroys oldest 3 Babblers when new Babbler Egg is created and limit is reached.
Tunnel entrance open small.gif

Gorge Tunnel
Large orifice that creates an underground organic tunnel, which connects to the owner's other existing entrance at anywhere on the map.
  • Grows when on Infestation, but requires Heal Spray when on uninfested ground.
    • Spreads Infestation around itself once grown.
  • Can only be built on flat ground with enough space above to exit.
  • Lifeforms, Marines, and Exosuits can enter the tunnel by standing on top of the entrance, then rapidly travel between each entrances' locations.
  • Acidic bile inside the tunnel corrodes Frontiersmen Armor.
  • Maximum 2 per player.
    • Digestible by owner to remove from play when 2 Gorge Tunnels exist.
    • Destroys oldest Gorge Tunnel when new one is created and limit is reached.
    • If both Gorge Tunnels are destroyed, the tunnel will collapse and kill all players inside it.
Webs small.gif

Strand of webbing that slows Marines and Exosuits on contact.
  • Place at two points to create a strand of webbing.
    • Can stick onto walls and ceilings.
    • Can stretch several times its normal length.
  • Breaks when touched by Marine or Exosuit.
    • Slows down the target temporarily.
    • Prevents jumping and using Jetpack.
  • Can only be removed by Welder, Flamethrower, and grenade explosions.
  • Requires Biomass level 7 and Upgrade Gorge from the Hive.
  • Maximum 10 per player.
    • Cannot be digested.
    • Destroys oldest Web when new one is placed and limit is reached.

Basic Commander Built Structures

Basic Structures
Structure Description Additional Information
Cyst idle small.gif

Small structure that grows Infestation around itself.
  • Can be placed on uninfested ground.
  • Creates a chain of Cysts in between by placing one Cyst at the final location.
    • Each extra Cyst costs Team Resources.
    • Must connect to active Hives and other Cysts to survive.
  • Grows only when its parent Cyst is grown.
Harvester deploy small.gif

Harvests Team and Personal Resources for the Kharaa to build, upgrade, and evolve.

Cocoon grow small.gif


Drifter grow small.gif

Cocoon - Grows and hatches into a Drifter.

Drifter - Worker unit that speeds up structure growth.
Hive spawn idle.gif

Egg flinch small.gif

Hive - Kharaa command structure that houses the Alien Commander.

Egg - Spawn point for Kharaa players into the Skulk.
  • Grows only on an unoccupied Tech Point.
  • Auto-builds at 70% build rate without Grow or Heal Spray.
  • Heals nearby lifeforms, spreads Infestation over a large area, and spawns Eggs periodically.
    • Cannot heal when on fire.
  • Can spawn extra Eggs using Hatch ability.
    • Alien Commander can pre-evolve Eggs into different lifeforms for players to spawn from or use.
  • Unlocks 1 Biomass level by itself, and can upgrade 2 additional levels (maximum 3 levels per Hive).
  • Enables Upgrade Gorge to unlock Babbler Egg, Bile Bomb, and Web abilities based on Biomass level.
  • Evolves into 1 of 3 different Hive types to unlock Evolution structures.

Threat pheromone icon.gifHeal pheromone icon.gifExpand pheromone icon.gif

Waypoints that are only visible to all Kharaa players.
  • 3 different types: Threat, Need Healing Here, and Expanding Here.
  • Can be placed anywhere on the map.
  • Fades away over time.

Advanced Commander Built Structures

Advanced Structures
Structure Description Shared Attributes Additional Information
Crag spawn small.gif

Semi-static defense that heals nearby Kharaa units and structures.
  • Grows only on Infestation.
  • Costs Supply to build.
  • Auto-builds at 70% build rate without Grow or Heal Spray.
  • Can slowly move but takes damage when away from Infestation.
  • Healing does not stack and maximum 3 targets per Crag.
    • Cannot heal or use Heal Wave when on fire.
  • Unlocks Heal Wave ability when a Crag Hive is complete.
    • Heal Wave increases the amount of healing from the Crag.
Shade spawn small.gif

Semi-static defense that renders all nearby Kharaa units and structures invisible.
  • Cloaked units and structures are transparent but cause visible distortion.
    • Cannot cloak or use Ink when on fire.
  • Unlocks Ink ability when a Shade Hive is complete.
    • Ink shrouds the area around the Shade in a black cloud that obstructs sight and stops Scan detection.
Shift spawn small.gif

Semi-static defense that recharges nearby lifeforms' energy.
  • Cannot energize or use Echo when on fire.
  • Unlocks Echo ability when a Shift Hive is complete.
    • Echo allows the Alien Commander to move structures near the Shift to anywhere on Infestation.
Whip spawn small.gif

Semi-static defense that whacks nearby Frontiersmen units and structures.
  • Can uproot from Infestation to relocate itself.
    • Does not take damage when away from Infestation.
    • Cannot attack while uprooted.
  • Cannot attack or use Bombard when on fire.
  • Matures over time to gain Bombard ability that throws an anti-robot, structure, and Armor bile sac over a long range.
Shell spawn small.gif

Unlocks Carapace, Regeneration and Vampirism evolutions.
  • Grows only on Infestation.
  • Auto-builds at 70% build rate without Grow or Heal Spray.
  • Evolutions' power level increases with number of same structures (maximum 3 levels).
  • Requires Crag Hive to build.
Veil spawn small.gif

Unlocks Aura, Focus and Camouflage evolutions.
  • Requires Shade Hive to build.
Spur spawn small.gif

Unlocks Adrenaline, Celerity and Crush evolutions.
  • Requires Shift Hive to build.