Antlion (Half-Life 2)

Antlions are a fictional insect-like alien species found in Valve Software's first-person shooter action computer game, Half-Life 2. They ended up on Earth after being transported from Xen by the portal storms, and adapted particularly well to their new environment. While they prefer sandy environments, these Antlions otherwise have little in common with real-life antlions, preferring to directly assault prey rather than passively trap them. Antlions appear starting in the “Highway 17” chapter of Half-Life 2 and remain well into the “Nova Prospekt” chapter. They are a constant threat throughout Half-Life 2: Episode One, and the beginning of Half-Life 2: Episode Two prominently focuses on their nests.

Antlions
Antlions live in underground colonies, typically situated in sandy areas such as beaches. They usually hide under the sand, waiting for anything to venture near, at which point they quickly surface and tear it apart. Their aggression is not limited to humans or the Combine, and they will attack other xenofauna such as headcrabs. Antlions sense a victim's presence via vibrations transmitted through loose soil or sand. This makes it possible to safely venture through Antlion territories by walking solely over foreign items placed on the sand, or by walking across rocks. Once on the surface, Antlions can fly short distances to rapidly approach their prey. The Combine refer to Antlions as "virals," "biotics," or "exogens", as a soldier can be heard mentioning a "full biotic overrun" of the Nova Prospekt facility; however, the term biotic may also be a general term used by the Combine for any hostile life form, including Antlions and headcrabs.

In Half-Life 2, a swarm of five Antlions will usually emerge when the sand is disturbed. If the player is still on sand when one is killed, another will spawn to replace it. Half-Life 2: Episode One introduces the concept of Antlion burrows, essentially large holes in the ground from which Antlions spawn. Unless covered, burrows continually spawn Antlions to replace those killed. Refuge may be sought in water, since Antlions cannot swim and quickly drown when they come into contact with it. It is also possible to flip the Antlions over with a burst from the Gravity Gun, allowing for a quick escape. The Antlion group mentality makes up for their lower health totals: an individual Antlion is relatively easy to kill, but its friends will attack while the player is occupied. Antlions are the only enemies in Half-Life 2 that gib rather than becoming ragdolls if killed with a strong weapon.

The behavior of Antlions in respect to sound, vibration and aversion to water is analogous to that of Sandworms in the Dune universe. However, while the use of Thumpers to produce powerful vibrations attracts Sandworms, Antlions are repelled by the very same tactic, possibly experiencing sensory overload or pain in their presence, due to their sensitivity to vibration. Similar fictional creatures include the graboids of the film Tremors, which react in a similar way to loud noises such as explosions, and the arachnid warriors in the film version of Starship Troopers.



Antlion Guards
Far larger and stronger, Antlion Guards (with the binomial name Myrmidont giganticus ) have command and control over other Antlions. Unlike the smaller Antlions, they cannot jump or fly, but make up for this by being much faster. Their primary attack is a charging head butt, which can also turn any loose objects within the Guard's line of sight into deadly projectiles if the Guard hits them.

While traveling along the coast, an encounter ensues with a Guard. After its defeat, a Vortigaunt extracts its pheropods and gives them to Gordon. To Antlions, the pheropods identify Gordon as a Guard and therefore do not attack. When Gordon encounters additional Guards later in the game, the Antlions under his command refuse to approach. The pheropods (called "bugbait" by the Rebels) can be used to send commands to the Antlions to follow Gordon by squeezing them or attack his enemies by throwing them. It's not clear where Gordon gets replacements, as the weapon has unlimited ammo. Combine Overwatch soldiers will flail about for several seconds if a pheropod is thrown directly at them, due to the powerful aromatic pheromones emitted upon contact.

As Gordon progresses into Nova Prospekt, a Combine Overwatch soldier can be heard saying, "Warning, primary target is, uh, engaged in, uh, command and control tactics with biotics. Repeat: Primary target has tactical C&C over biotics," implying that Overwatch has never encountered a human utilizing the aid of Antlions before.

An image caption on the official Episode One site refers to an Antlion Guard seen in a screenshot as an "Ant Lion Queen", although it bears no difference in appearance from other normal ones (Alyx calls them Guards). Though this could simply be an error, it may indicate that this particular specimen is a female of the species, or that possibly all Antlion Guards are female. There is an unused alternate texture for the Antlion Guard in the Half-Life 2 and Episode One game cache files, giving the creature a blue-color skin. On the Valve developer wiki, it is referred as a "Cavern dweller."

In Half-Life 2: Episode Two, the player encounters an Antlion Guardian, which is a form of Antlion Guard that glows yellow and poisons the player upon contact, and when attacked at close range by the player (similar to the Antlion Workers). This neurotoxin effect is missing in the battle where the player takes on the Guardian and a Guard above ground later in the game; this is because this Guardian is merely a reskinned Antlion Guard, created by the developers so the player can "give a little payback to the creature that followed him through the caves." The player was not allowed to kill the Guardian in the previous mission, as the mission required it be alive. Episode Two also introduces a new effect for the Antlion Guards, causing them to bleed from their 'heads' when severely damaged.



Antlion Grubs
Antlion Grubs are apparently the larval form of Antlions, and were first seen in the leaked beta version of Half-Life 2. They were cut before the final release of Half-Life 2, but returned in Episode Two. Antlion Grubs glow, providing much of the light in the dark underground caverns, and die when stepped on. Upon death they drop a yellow blob that confers a small amount of health upon the player. Although they were originally designed to alert other Antlions when they were killed, this aspect was removed. However, a minor character does at one point suggest that stepping on Antlion grubs does attract the attention of Antlions. According to the Valve developer wiki, this was removed as it made players afraid to kill grubs for the health goo they dropped, making the cavern section of the game extremely difficult.

In their larval state, antlion grubs are docile and cannot harm the player in any way. They cling to nearly any hard surface and feed off a substance which appears to be the same material that antlions build their nests out of.

Antlion Workers (Acidlions)
Antlion Workers or "Acidlions" are similar to normal Antlions in terms of their legs and abdomen. They have a head similar to that of a termite, and possess small wings used for flying short distances.

Antlion Workers can spit toxic acid over long range, inflicting a large amount of splash damage. This may be an homage to the Bullsquid of the original Half-Life, which had a similar attack. Because they have a ranged attack, Antlion Workers typically do not engage in close combat, allowing standard Antlions to fulfill this role. However, they are capable of attacking the player with their legs at close range. Antlion Workers seen later in the game will normally be accompanied by normal Antlions; this may show some form of leadership role. They are more resilient than normal Antlions, and will explode into a spray of acid upon death that will damage anything in a small radius.

Antlion King
An "Antlion King" was touted in a few previews. It appeared to have a face resembling more of an alien, as it has few insectoid qualities. According to Half-Life 2: Raising the Bar, Gordon was supposed to fight one of these in a boss battle underground. However, as the above-ground levels gained more detail and the underground levels shrank, the decision was made to cut the Antlion King from the game. It may be the center of Antlion colonies if they are social creatures like bees or ants, but this is unlikely as the title of "King" suggests that this Antlion is male. However, Raising the Bar also indicates that the Antlions were to have a patriarchal society as opposed to a matriarchal one, possibly indicating that they mate in a different way than terrestrial insects. The Antlion King was originally to be fought in a large underground nest area with Antlions covering the walls and ceiling to such an extent that there was no room for the king. Raising the Bar contains a slightly comical comment from a Half-Life 2 game designer who tried to sculpt the Antlion King out of clay, which took many attempts to create without it collapsing. He also mentions that, for reference of scale, Gordon is stuck between the model's toes.

Defense
Along the coastline are areas protected by mechanical devices the Combine call Restrictors, dubbed "Thumpers" by resistance members. By repeatedly pounding the earth with metal beams, the vibrations produced deter the Antlions. Large-scale Restrictors appear around the perimeters of Nova Prospekt.

In Half-Life 2, stretches of beachsides devastated by Antlions prompted the Combine to set up Restrictors to combat the threat. Within City 17, the base of the Citadell functions as a massive Restrictor, operating constantly on the sides of the structure. This implies that Antlions have overrun much of the land. The destruction of the dark fusion reactor in the Citadel ceases most of the Citadel's functions, effectively nullifying the only defense City 17 had against an Antlion invasion. Antlion attacks in City 17 commence soon afterwards.

In Episode One, it is also revealed that it is possible to block Antlion burrows with large, heavy objects such as cars. Once blocked, Antlions can no longer emerge to the surface.

Reproduction
It is unknown how Antlions reproduce, but it is possible that they live in social colonies like bees or ants. This and the presence of a caste system are supported by the existence of Antlion Guards and the fact that Antlions commonly work together (another possibility would be that Antlions have an extreme form of sexual dimorphism). However, a resistance member also mentions in Half-Life 2 that the Antlions have a "spawning season". He could have been referring to adolescent females breeding with drones, however, Gordon only encounters one type of Antlion throughout the entire Highway 17 trip. This suggests that Antlions may be able to breed individually, as opposed to the colony theory. Additionally, some suggest that currently mating Antlions could be residing underground. They could also be independently breeding creatures that live in queen-less colonies. It should also be noted that Antlions have different yellow, black, or red markings and patterns. What relevance this has with creatures that are supposedly sightless is unknown, but it may be indicative of gender.

It needs to be pointed out that, as aliens from another dimension, there is no reason that Antlions would necessarily reproduce in a fashion similar to terrestrial organisms. It is possible that Antlions have three sexes, and Guards are a non-reproducing neuter sex whose only function is guarding nests.