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Not to be confused with Voltigore.

General information
  • Nihilanth slaves (HL)
  • Resistance members (HL2)
Individual information
  • 30/30/60 (HL)
  • 100 (HL2)
  • Green electrical attack
  • Claws
  • Gravity manipulation
Game information
  • monster_alien_slave
  • monster_vortigaunt (HL)
  • npc_vortigaunt (HL2)
Voiced by
"Our life is worthless unless spent on freedom."
― Vortigaunt[src]

Vortigaunts,[2][3] also known as Alien Slaves[4] and often referred to as Vorts by humans, are a hive-minded, energy-wielding, sapient alien race found throughout the Half-Life series.[5]


Vortigaunts are highly intelligent and social creatures. Throughout the series, they can often be seen in pairs or groups, and information is spread among them through low-grade telepathy.[6] In appearance, a Vortigaunt is roughly humanoid with two legs and two arms with an additional arm protruding from its chest. This extra vestigial limb is a physical trait also found in other bipedal, sapient species from Xen, including the Alien Grunt and the Nihilanth. Vortigaunts have mottled green-brown skin, sharp teeth, and clawed hands. They have a slightly hunched posture, and their faces are dominated by a large, single eye with a maroon sclera and a heterochromic red-yellow iris with a yellow pupil surrounded by five smaller eyes in the original game and only three in the sequel. They have two noses on each side of their head visible as small tubes.[a] They were given a smoother, shinier, and slug-like appearance in Episode Two.[b] In Half-Life: Alyx, they have rough skin, darker eyes, three fingers on each hand (as opposed to two in previous games), and three-toed feet (unlike the previous hoof-like appearance).

Vortigaunt cooks in Black Mesa East.

Brief glimpses into the Vortigaunt culture can be gained from their occasional spoken monologues. Based on their comments, it seems that the species has endured slavery for many generations,[7] and enforced servitude appears to have formed the bedrock of Vortigaunt history and culture up to the events of the first Half-Life. They have many traditions, including an apparent oral tradition of passing down poetry,[8] songs,[9] and philosophical statements[10] from generation to generation. Unlike other aliens, they don't eat human corpses. However, they demonstrate themselves as meat-eaters as they are seen cooking Headcrabs in Half-Life 2, first in a cave over a fire and later in a kitchen at Black Mesa East, and again in Half-Life: Alyx with Gary prominently declaring them as a form of "sustenance." Their ancestors also once practiced Antlion husbandry.[11]

Vortigaunts healing Alyx.

In Half-Life 2, Vortigaunts now demonstrate the ability to vocalize in human languages. However, their use of English is slightly strange, as they often use verbose sentence structures and cryptic phrasings. Vortigaunts also tend to refer to characters by adding the definite article "the" before their name, such as "the Freeman" or "the Alyx Vance." Vortigaunts usually refer to themselves in the third person.

Vortigaunts possess their own native form of vocal communication which is referred to as Vortigese. This method of speaking is described as "flux shifting" and can be heard in rare instances, such as their battle cries during combat or when two Vortigaunts are engaged in conversation. According to the Vortigaunts, flux shifting cannot be understood by "those whose Vortal inputs are impaired."[12]


Vortigaunts believe in a binding life force which they call the "Vortessence."[13] While the exact nature of this concept is left unclear, the Vortigaunts describe it as the fabric of the universe which connects everything living.[14] When Alyx is resuscitated in Episode Two, the Vortigaunts remark that, while they were the ones who physically healed her mortal wounds, it was Gordon who retrieved her Vortessence. In Half-Life: Alyx, the formerly imprisoned Vortigaunt Gary mentions that the Combine had drilled into his brain to forcefully sever his connection from the Vortessence. This procedure has broken his telepathic communication with other Vortigaunts and impaired his perception of time, leaving him unable to distinguish which events have already occurred and what is still yet to happen.

Behavior and skills[edit]

Half-Life and its expansions[edit]

Vortigaunt workers in the Mines.

In their debut appearances, Vortigaunts are slow and fairly easy to kill, usually not posing a large threat. They show up in groups and often act as support for Alien Grunts. They possess a powerful and accurate long-range electrical attack, able to summon electricity from their hands in the form of green lightning-like beams. They must charge up briefly and remain stationary before their attacks, leaving themselves vulnerable in this period. They also attack with their claws in close range.

If one is severely wounded, it becomes frightened and will choose to run away from its opponent rather than fight. It will continue fleeing unless cornered, in which case it will only defend itself by clawing its foe. However, if the enemy turns his back, the Vortigaunt will resume using its electrical beam to attack from behind.

Half-Life 2 and its Episodes[edit]

Extracting Bugbait from an Antlion Guard.

In Half-Life 2, their electrical attack is far more devastating as it tends to immediately kill whatever it hits with a massive amount of force. They can be seen using their electrical attacks for non-combat purposes several times in the game, such as when charging up a transformer in Black Mesa East and when a Vortigaunt extracts Bugbait from a dead Antlion Guard. The latter process is said to be one of their ancestral practices.[15] They are also capable of manifesting their energy in a different productive form, visible as a blue energy stream. This is used to power up electrical devices, fuse objects together such as the Gauss Cannon which is affixed to the Airboat, and even charge Gordon's HEV Suit. Although not seen in the game, they can punch and kick enemies in close combat.

In Episode Two, Vortigaunts can perform takedowns on Antlions and Zombies. When surrounded by Antlions, they use their concussive blast attack to dispel and knock over Antlions nearby, giving the player the opportunity to finish them off.

Under certain circumstances, Vortigaunts are capable of manipulating space and time to an impressive degree.[16] In Episode One, a group of purple-colored Vortigaunts use their ability to teleport and rescue Alyx Vance. They also free Gordon from his stasis and are shown blocking the G-Man from interfering using a blue energy shield. In Episode Two, with the aid of a larval extract from an Antlion nest, a group of Vortigaunts are capable of healing Alyx after she sustains near-fatal injuries from a Hunter.

Half-Life: Alyx[edit]

In Half-Life: Alyx, Gary, a Vortigaunt, is shown to be able to manipulate gravity and cause objects to levitate, and uses this power to save Eli Vance from falling to his death. He can also imbue mundane pieces of cardboard with Vortigaunt energy to make them float independently and manipulate them to a fine degree to form complex three-dimensional images.

Throughout the Quarantine Zone, other Vortigaunts are found held captive inside Prisoner Pods where they're being used by the Combine as power generators. Several key Vortigaunt-powered substations in this area are used to the power the Vault.


Half-Life and its expansions[edit]

Deceased Vortigaunt with its collar and shackles removed.

Vortigaunts are common enemy ground units featured in Half-Life and its expansions. Described as low-caste aliens,[2] they are used as slave workers and drone soldiers in the military forces. They first appear in the chapter Anomalous Materials during the Resonance Cascade. Several Vortigaunts teleport in from the ceiling of the test chamber, disappearing as they near the floor. A few moments later, when Gordon Freeman is briefly teleported to Xen, he appears in a dark room with four Vortigaunts standing in a half-circle around him; however, they do not attack. The first hostile encounter with the species occurs in Unforeseen Consequences, after which they act as standard enemies for the rest of the game and in the ensuing expansions.

In Xen, Gordon comes across a number of Vortigaunts working in the Mines which, despite being aware of his presence, are not aggressive towards him unless attacked first or they become startled by nearby gunfire. They do, however, resume their normal hostile behavior while in the presence of Alien Controllers. Here, they are able to heal themselves by using Healing Chambers if they become injured.[17]

In Decay, a dead Vortigaunt with its collar and shackles removed is found in the Alien Quarantine Labs. These items are separately connected to machinery testing its electrical capabilities. In the PlayStation 2 version, players are able to play the game as a Vortigaunt through two methods: Xen Attacks, which is a bonus mission for Decay featuring the drones X-8973 and R-4913, and in Alien Mode which allows the player play through Half-Life as a Vortigaunt.

Half-Life 2[edit]

Vortigaunt tortured to death in cell block A7 in Nova Prospekt.

In Half-Life 2, Vortigaunts return as allies. It is revealed that Gordon Freeman inadvertently liberated them when he destroyed their masters, including the Nihilanth, during the Black Mesa incident. Rather than fall under the dominion of the Combine, the Vortigaunts joined the human Resistance[5] after being persuaded by Eli Vance, the first human being to make peaceful contact with them and earn their trust.[18] Various Vortigaunts are seen in Resistance-controlled locations, such as Black Mesa East, outposts in the Canals, and the Vortigaunt Camp situated not far from Nova Prospekt, assisting Gordon in his journey.

The Vortigaunts credit Gordon with their freedom and hold him in high esteem as "The Freeman." However, not all Vortigaunts have been liberated. In the chapter Point Insertion, it is possible to catch a glimpse of a Vortigaunt known as Sweepy still serving under the Combine's rule. Wearing a collar and shackles similar to those worn in the original game with an additional band around the waist, the Vortigaunt is shown slowly and meticulously using a push-broom to sweep dirt and garbage in the City 17 Trainstation.

When exploring Nova Prospekt, the player comes across a deceased enslaved Vortigaunt lying in a restraint chair. Interestingly, this occurs in block A2 in which the Overwatch had directed shortly before to "De-service all political conscripts in block A2 - prohibit external contact." It appears that the Vortigaunt had been executed through electrical torture by the Combine, substantiating Alyx's comments that the Resistance's only knowledge of the prison is through telepathic communications from Vortigaunts taken there for persecution or interrogation.

Half-Life 2 Episodes[edit]

Vortigaunts saving Alyx at the beginning of Episode One.

At the beginning of Episode One, a group of purple-colored Vortigaunts rescue Alyx from the destruction of the Citadel's Dark Fusion Reactor and free Gordon from the control of the G-Man, teleporting both of them to safety outside of the Citadel.

Vortigaunts play a much larger role in Episode Two, with one in particular acting as a significant sidekick for the early portion of the game. After a Hunter mortally wounds Alyx and traps Gordon under a collapsed building, a Vortigaunt saves the former from being eaten by an Antlion. The Vortigaunt then stabilizes Alyx's condition and carries her to an underground Resistance outpost where, with the help of three more Vortigaunts, they beat back a heavy Antlion incursion. The Vortigaunt then accompanies Gordon in a quest to harvest the larval extract of the Antlions to save Alyx's life. The Vortigaunt proves a valuable companion, as it kick starts generators by giving them an electric jolt. Eventually, Gordon is able to access the Nectarium, the center of the nest, where the Vortigaunt harvests a small quantity of the larval extract. Both Gordon and the Vortigaunt travel back to the outpost and initiate a ritual to heal Alyx.

After the Vortigaunts begin the ritual, they begin to turn purple-colored just as those witnessed at the beginning of Episode One. It is at this point the G-Man reestablishes contact with Gordon. He states "...but I had to wait until your... 'friends' were otherwise occupied...", suggesting up until then the Vortigaunts had somehow been keeping the G-Man at bay. The Vortigaunts are unaware of the intrusion and never mention the G-Man, nor the service they rendered Gordon and Alyx at the beginning of Episode One.

The Vortigaunt then accompanies Gordon and Alyx a little further on before heading back, mentioning that he and his cohorts are occupied with searching for Combine Advisor pods. Another Vortigaunt, given the name Uriah by Dr. Magnusson, aids Gordon briefly later on in the episode at White Forest.

The game-over messages in Episode Two appear to be written from the perspective of the Vortigaunts.

Half Life: Alyx[edit]

"Report the Vort" propaganda poster.

Several Vortigaunts appear in Half-Life: Alyx, and anti-Vort Combine propaganda can be seen scattered throughout the city. While Alyx is traveling through the Quarantine Zone, she sees several murals depicting the past events of Half-Life and (unbeknownst to her) foreshadowing new events coming in Half-Life 2, such as Gordon's return. She eventually meets the painter, Gary, a lone Vortigaunt who was captured and tortured by the Combine but managed to escape their clutches. Gary tells her that the Combine have been imprisoning his kind and that she will rescue them soon.

Later, when Alyx is trying to rescue her father Eli from the wreck of a Razor Train, she finds him holding onto a hanging platform above a pit. Just as she's reaching for his hand, Eli loses his grip and falls. However, Gary miraculously reappears just then, saving Eli by halting his descent and levitating him back up to safety. The Vortigaunt then accompanies Eli back to Russell's Lab.

After sabotaging the first of several substations keeping the Vault afloat, Alyx inadvertently frees a conductor Vortigaunt that was tuning power to the airborne fortress. The Vortigaunt thanks her for her efforts and explains that the Combine have been draining the energy of Vortigaunts to "protect their weapon." He urges her to continue on her path to the Vault as he states the Vortigaunts will "extract [themselves]" from the other substations and "exact [their] own vengeance" against the Combine. True to his words, the Vortigaunts have taken out all the remaining substations by the time Alyx makes it to the Vault.

Related Achievements[edit]

Half-Life 2
Hl2 find vortigauntcave.png Vorticough (13G)
Discover the hidden singing Vortigaunt cave in chapter Water Hazard.

Behind the scenes[edit]


Early design by Chuck Jones.

In Online Gaming Review's early Half-Life Monster of the Week Feature preview, Vortigaunts were given the taxonomic designation "Xenotherium subservilia." They were described as being highly subservient creatures bred to be unquestionably loyal to its masters. They had an indiscriminate diet, choosing to abstain from even the lowly Chumtoads, as they were only afforded the scraps from battlefield remnants and whatever little else they could scavenge. Vortigaunts are said to regularly groom Alien Grunts, their most common masters, and dine on the ectoparasites gathered in this process. When ordered into combat, they fight with a fervent vigor heedless of their own personal risk as they fear the wrath of their superiors more than their enemies. They are commonly sent first in battles as cannon fodder or bait. Outside of the eye of their masters, Vortigaunts would act remarkably cowardly and choose to flee from hostility, becoming virtually harmless. They were thought to be of low intelligence, seemingly being incapable of independent thought and their original survival instincts being altered by their masters. Nonetheless, it was still apparently necessary for its overlords to implement slave collars on all units to keep any chance of rebellion under control.[19]

Gordon Freeman was originally to win the Vortigaunts over as allies on Xen, then leading them to outright rebellion. This plan proved impractical but was reused for Half-Life 2.[20]

Vortigaunts have an unused melee attack called Major Rake[2] (clawrake in the code) which is a duplicate of their claw attack in the code but stronger.[21] Code found in the Half-Life SDK reveals some cut abilities and behaviors. Vortigaunts could resurrect dead Vortigaunts using their beam attack. They also had a "bravery" check in which, if they were in the presence of numerous dead Vortigaunts, they would lose the nerve to continue fighting and opt to flee.[22] Unused animations found in Day One depict the creature being grabbed and eaten by a Barnacle. The notes for the Half-Life Alpha version 0.61 state that each Vortigaunt was to have an unknown device called a "control sphere" accompanying them.[23] This may be related to the unused alien creature, Sphere.

Half-Life 2[edit]

In Half-Life 2, the Vortigaunts are voiced by Louis Gossett Jr. According to Bill Van Buren, casting the Vortigaunt was a challenge. They had been receiving poor audition tapes, so they gave the casting agents some additional direction. They stated they wanted somebody "speaking human language, but not human." Van Buren gave the examples of Vincent D'Onofrio as Edgar in Men in Black and Gossett as Jeriba Shigan in Enemy Mine. They soon got a call from Gossett who, it turns out, was interested in the part.[24] It's said that Gossett's voice lent itself to a mystical and mysterious characterization of the Vortigaunt.[6] Robin Williams also expressed interest in voicing them, but scheduling conflicts prevented him from playing the role.[25]

Vorti-Cell concept art.

Vortigaunts were to play a larger role in Half-Life 2. City 17 was originally to be filled with Vorti-Cells, Combine devices used as stations siphoning power from trapped Vortigaunts.[26] They were intended to be greater integrated into City 17's population, but as most of the development team's resources were spent on creating the urban combat, this plan did not come to fruition, leaving their numbers to be noticeably small in the final game. The developers instead decided to implement the creatures far more substantially in the sections of the game taking place outside of the city.[27] The concept of Vorti-Cell was brought back in Half-Life: Alyx as power generators used in various areas, notably the Vault's substations scattered throughout the Quarantine Zone.

Some of their skills and sequences were cut by release. Vortigaunts had the ability to destroy grenades with their electrical beams in a special defend mode.[28] They could stomp Headcrabs and crush them with their feet. The crushed Headcrabs were to use a unique squashed version of their models.[28] The Scout Car's attached Tau Cannon was apparently supposed to be removed from the vehicle by a Vortigaunt. An unused animation shows an individual firing the gun.[29] According to David Speyrer, the dead Vortigaunt discovered in Nova Prospekt was actually a change made late into the development of the game as it was originally intended to be found alive in its cell. The player could free the Vortigaunt who would then tag along as an ally in combat. As there was not enough time to complete the necessary work, the sequence was deleted, but they kept the concept in mind for the future.[27] The leftover entities still present in the map indicate that this sequence was to feature the Tau Cannon.[30] Their Half-Life 2 iteration also has unused animations for being grabbed and eaten by a Barnacle.

Half-Life 2: Episode Two[edit]

In Episode Two, the Vortigaunts are voiced by Tony Todd. In his reading, the team heard new possibilities for a Vortigaunt "who is more of a mystic martial artist." With new attack animations and companion behavior, they worked with Todd to build the Vortigaunt into a powerful ally, "a full-on alien ass-kicker."[6] As noted by John Guthrie, the team, however, didn't want to make them too powerful as that would take away from the player's fun yet still wanted him to be a good ally to have around. One solution was the shock attack where the Vortigaunt would stun a group of Antlions so that the player could finish them off.[6]

Series writer Marc Laidlaw stated that one of the most important goals with Episode Two was to expand on the Vortigaunts as characters. As such, Valve added new behaviors, new animations, and new audio to them. In the developer commentary, Danika Wright noted that turning the Vortigaunt into an expressive character was a challenge for the animators given that they don't have a traditional face. To bring out their personality, the animators concentrated on shifting bodyweight and broad hand gestures. Most importantly, where human characters tend to move their heads a lot for emphasis, the developers concentrated the Vortigaunts' performances on expressive spinal motions.[6]

Some of the Episode Two locations were designed specifically with Vortigaunts in mind. Doug Wood, an animator at Valve, said that during the development of the Antlion battle in the Victory Mine, they were careful to make it fairly easy for the players to sit back and enjoy watching the Vortigaunts clear the room of Antlions during the last wave. The developers wanted to show off the Vortigaunts' new abilities and get the player excited about the role they were going to play as active allies in the struggle against the Combine.[6] According to Jason Brashill, after a new model was created for the generator, the developers decided to exploit the Vortigaunt's natural relationship with electricity by having him charge the generator in a similar way he charges Gordon's suit. They were then able to use generators as "Vortigates" throughout the level to indicate areas the player could enter only with a Vortigaunt's assistance.[6] According to Leslie Hall, the Vortigaunt's dispel attack that takes out a swarm of Antlions looks most impressive when seen from above, though that's not a perspective the player gets very often in the Antlion tunnels. Thus, the team designed the exit from the battle at an overrun Resistance outpost in the Victory Mine purely to give the player a view from above allowing the Vortigaunt to put on a display.[6] Ted Backman remarked that making the Overwatch Sniper Rifle found near the Muscle Car bridge visible and accessible to the player required the team to come up with a way to make the rifle usable only with the Vortigaunt's help.[6]


Until the game's story had been elaborated upon and proper names were created, the alien species was known simply as Alien Slaves, a code name which was primarily adopted by players early on. The name "ISlave" also appeared in the game files and in the filenames of Chuck Jones' concept art.[31] It was eventually given the name of "Vortigaunt" during the development of Half-Life,[1] but it was never mentioned during gameplay. This title was first publicly revealed in the Prima strategy guide for the game.[2] Additionally, the in-game monster entity has two internal designations in the code: the generic monster_alien_slave along with monster_vortigaunt. Vortigaunts are also referred to as "Vortigons" in text messages left over by the developers in the test map hl1devteste included in Half-Life: Source.[32] The name "Vortigoth" is also referenced in the Episode Two source code for unknown reasons.


Vortigaunt plush.

In Half-Life 2's language localizations, the Vortigaunts are voiced by Tony Beck in French, Stephan Grothgar in German, Javier Alcina in Spanish, and Diran Meghreblian in Russian.[29] The Vortigaunts are mentioned in Marc Laidlaw's BreenGrub, a fan fiction story set in the Half-Life universe. The cancelled Half-Life expansion, Hostile Takeover, was planned to have an energy weapon called the Vortigaunt Gun.

A Vortigaunt plush toy designed by Dhabih Eng was released through the online Valve Store in December 2006. A Santa hat was included to commemorate the holiday sale.[33][34]

In modding[edit]

In the Half-Life mod Point of View, one can play as a Vortigaunt during the Black Mesa Incident.


  • According to Marc Laidlaw, the first Half-Life movie treatment pitched to Valve climaxed with a tearful reunion between enslaved Vortigaunts and their Vortiwives and children.[35][36]
  • In Half-Life: Opposing Force during the second chapter Welcome to Black Mesa the large freight elevator brings down two vortigaunts. Their entity names are Banjo & Kazooie. This is a clear reference to the Rare Platformer series under the same name.
  • In Half-Life: Opposing Force during the sixth chapter We Are Not Alone inside the Hazard Course, a vortigaunt can be seen desperately trying to attack the Gina Cross hologram. It's entity name is Greedo. This is a clear reference to the Star Wars character under the same name.
  • In Half-Life: Blue Shift during the sixth chapter Power Struggle a Vortigaunt enters through the exist door. Their entity name is chicken_de_china which is a clear lyric reference to the Barenaked Ladies song "One Week".


Concept art[edit]



Gary's mural[edit]


List of appearances[edit]

Main games[edit]


See also[edit]

Notable Vortigaunts[edit]


  1. The names of the textures used for the tubes are: Nose1.bmp, for the side of the tubes, and Nostrils1.bmp, for the holes on the tubes. In Half-Life 2, the tubes use the flexes used for the nose of human characters.
  2. This updated look was later implemented into Half-Life 2 and Episode One in The Orange Box 2010 update.


Combine OverWiki has a list of quotes for Vortigaunt.
Combine OverWiki has more images related to Vortigaunt.
  1. 1.0 1.1 Chuck Jones' personal website
  2. 2.0 2.1 2.2 2.3 Half-Life Prima Guide
  3. Half-Life, entity name: monster_vortigaunt
  4. Half-Life, entity name: monster_alien_slave
  5. 5.0 5.1 Half-Life 2 Prima Guide
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Half-Life 2: Episode Two commentary
  7. Vortigaunt: "We have endured these chafing bonds for eons, yet a single moment of further servitude seems intolerable!" Half-Life 2 (Vortigaunt Quotes)
  8. Vortigaunt: "Our finest poet describes it thus: Gallum galla gilla ma." Half-Life 2 (Vortigaunt Quotes)
  9. Vortigaunt: "Your song we sing and shall sing for eternity. No matter the consequences of this struggle." Half-Life 2 (Vortigaunt Quotes)
  10. Vortigaunt: "We are mindful of the words of our greatest philosopher: companum gannennen vorgenot!" Half-Life 2 (Vortigaunt Quotes)
  11. Vortigaunt: "Antlion husbandry was once our ancestral practice."Half-Life 2: Episode 2 (Vortigaunt Quotes)
  12. Half-Life 2
  13. Vortigaunt: "Communion of the Vortessence. And that other: a deeper mystery. No deeper than the void itself." Half-Life 2 (Vortigaunt Quotes)
  14. Vortigaunt: "We are a tapestry woven of Vortessence. It is the same for you if only you would see it." Half-Life 2 (Vortigaunt Quotes)
  15. Vortigaunt: "Antlion husbandry was once our ancestral practice." Half-Life 2: Episode Two (Vortigaunt Quotes)
  16. The Orange Box Prima Guide
  17. YouTube favicon.png Half-Life - Vortigaunt Healing Itself on YouTube
  18. Vortigaunt: "The Eli Vance was our first collaborator." Half-Life 2 (Vortigaunt Quotes)
  19. Half-Life - Monster of the Week feature on Online Gaming Review (1997) (archived)
  20. Half-Life 2: Raising the Bar, page 19
  21. Half-Life, skill configuration file (skill.cfg)
  22. Half-Life SDK (islave.cpp)
  23. Half-Life Alpha (version .61) Notes (Half Life Main v6.doc) (August 26, 1998)
  24. Half-Life 2: Raising the Bar, page 153
  25. The Final Hours of Half-Life 2 on Gamespot (November 12, 2004) (archived)
  26. Half-Life 2: Raising the Bar, page 171
  27. 27.0 27.1 Looking Back... Half-Life 2: Episode One on Computer And Video Games (October 19, 2006) (archived)
  28. 28.0 28.1 Half-Life 2 leak
  29. 29.0 29.1 Half-Life 2 files
  30. Half-Life 2 (maps/d2_prison_03.bsp)
  31. Twitter favicon.png Tweet: "They were kinda code names until the story was fleshed out and they had proper cool names from what I remember." @ChuckJo25587237 (Chuck Jones) on Twitter (January 6, 2022)}
  32. "Use this turret to kill Vortigons. / Vortigons should spawn here with effects. When one dies, another will spawn 5 seconds later." Half-Life: Source developer message
  33. News on official Steam website (December 1, 2006) (archived)
  34. Vortigaunt plush toy on Valve Store (archived)
  35. PC Zone magazine, Issue 184
  36. Interview with Marc Laidlaw on (July 17, 2007) (archived)