R-4913 and X-8973

R-4913 and X-8973 are Vortigaunts from Half-Life: Decay. They appear in the bonus chapter Xen Attacks which can be unlocked if the player manages to obtain an A rank in all of the regular missions.

In the mission, the Nihilanth has assigned R-4913 and X-8973 to retrieve the crystals stolen from Xen by the Black Mesa Science Team (although it is later revealed that the crystals were actually stolen by the G-Man). Both Vortigaunts are able to regain health by damaging objects or enemies, supporting the theory that Vortigaunts can drain lifeforce/energy with their beam attacks.

Trivia

In the unofficial PC port, both Vortigaunts appear with a crowbar when looked at by the other player, while they both use only their claws and electrical attack, as any Vortigaunt. This is likely an unintended glitch.

In both versions of the game, the words "Valve" and "R-4913" are found in an air duct written all over the walls in the mission Code Green. These words are also found in a vent towards the end of Half-Life: Uplink.

List of appearances

Half-Life: Decay (First appearance)
Half-Life: Uplink (Non-canon; Mentioned by name; R-4913 only.)

Characters
Playable characters	Alyx Vance • Adrian Shepard • ATLAS and P-body • Barney Calhoun • Colette Green • Chell • Gina Cross • Gordon Freeman • Ivan the Space Biker (cut) • Mel (cut) • R-4913 and X-8973
Aperture Science	ATLAS and P-body • Caroline • Chell • GLaDOS • Greg • Mel (cut) • Doug Rattmann • Test Subject 042 • Test Subject 234 • Cave Johnson • Wheatley • Minor Aperture Science employees
Black Mesa	Walter Bennet • Wallace Breen • Barney Calhoun • Gina Cross • Gordon Freeman • Colette Green • Ivan the Space Biker (cut) • Richard Keller • Isaac Kleiner • Otis Laurey • Arne Magnusson • Miller • Rosenberg • Simmons • Eli Vance • Minor Black Mesa employees
Combine	314 URB-LOC 0017 Advisor • Barn Advisor • The Consul (cut) • Wallace Breen • Barney Calhoun • Unnamed Scientist • Vance (cut)
HECU	Dwight T. Barnes • Sharpe • Adrian Shephard • Minor HECU members
Resistance	All-Knowing Vortigaunt • Barney Calhoun • Consoling Couple • Odessa Cubbage • Dog • Gary • Gordon Freeman • Griggs • Helena Mossman (cut) • Johanson (cut) • Isaac Kleiner • Lamarr • Laszlo • Leon • MIRT • Arne Magnusson • Eli Maxwell (cut) • Judith Mossman • Odell (cut) • Olga • Russell • Sandy • Sheckley • Skitch (cut) • Unidentified deaf character (cut) • Uriah • Alyx Vance • Eli Vance • Vance (cut) • Victory Mine Vortigaunt • Minor Resistance members
Xen	All-Knowing Vortigaunt • Gary • Nihilanth • R-4913 and X-8973 • Uriah • Victory Mine Vortigaunt • Lamarr
Other	The Fisherman (cut) • The G-Man • Grigori • Larry • Samuel (cut) • Azian Vance

Xen
Creatures	Alien Aircraft • Alien Controller • Alien Grunt • Armored Headcrab • Barnacle • Boid • Bullsquid • Chumtoad • Fast Headcrab • Gargantua• Gonarch • Headcrab • Houndeye • Ichthyosaur • Leech • Lightning Dog • Nihilanth • Poison Headcrab • Protozoan • Snark • Standard Headcrab • Tentacle • Vortigaunt • Zombie
Flora and minerals	Crystal • Fungus • Healing Pool • Light Stalk • Trampoline • Tree
Weapons	Black Hole Gun (cut) • Ceiling Turret • Grenade • Hivehand • Sentry Cannon • Snark • Snark Mine
Technology	Healing Shower • Thumper
Creatures (cut)	Archer • Charger • Fast Walker • Flocking Floater • Kingpin • Mr. Friendly • Panther Eye • Prrobot • Sand Barnacle • Snapbug • Sphere • Stukabat • Unidentified Quiver Creature

Creatures
Antlions	Antlion • Antlion Grub • Antlion Guard • Antlion Guardian • Antlion King (cut) • Antlion Rollergrub (cut) • Antlion Soldier • Antlion Worker
Headcrabs	Headcrab • Fast Headcrab • Gonarch • Poison Headcrab • Standard Headcrab • Headcrab Shell • Armored Headcrab • Reviver • Bloody Headcrab
Race X	Gene Worm • Pit Drone • Pit Worm • Shock Roach • Shock Trooper • Spore Launcher • Sprite • Voltigore
Synths	Synth • Advisor Pod • Attack Synth (cut) • Combine Guard (cut) • Combine Mobile Mine (cut) • Combine Super Soldier (cut) • Combine Synth Elite Soldier (cut) • Crab Synth • Cremator (cut) • Combine Dropship • Combine Gunship • Hunter • Mortar Synth • Sacktick (cut) • Shield Scanner • Strider • Unidentified cut Synth (cut) • Wasteland Scanner (cut)
Xen	Alien Aircraft • Alien Controller • Alien Grunt • Archer (cut) • Barnacle • Boid • Bullsquid • Charger (cut) • Chumtoad • Fast Walker (cut) • Flocking Floater (cut) • Gargantua • Headcrab • Houndeye • Ichthyosaur • Kingpin (cut) • Leech • Mr. Friendly (cut) • Nihilanth • Panther Eye (cut) • Protozoan • Prrobot (cut) • Sand Barnacle (cut) • Snapbug (cut) • Snark • Sphere (cut) • Stukabat (cut) • Tentacle • Unidentified Quiver Creature (cut) • Vortigaunt
Zombies	Zombie • Fast Zombie • Gonome • Poison Zombie • Standard Zombie • Zombine • Zombie Assassin (cut) • Jeff • Lightning Dog Zombie • Bloody Headcrab Zombie • Armored Zombie
Other	Alien Fauna (cut) • Combine Advisor • Earth creatures • Hydra (cut) • Jeff • Jelly Blobber (cut) • Mantis Man • Particle Storm (cut) • Skitch (cut) • Stampeder (cut) • Test Subject 042 • Tripod Hopper (cut)

R-4913 and X-8973

Trivia

List of appearances

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