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.
- 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 airduct 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)
|Creatures||Alien Aircraft · Alien Controller · Alien Grunt · Barnacle · Boid · Bullsquid · Chumtoad · Gargantua · Headcrab · Houndeye · Ichthyosaur · Leech · Nihilanth · Protozoan · Snark · Tentacle · Vortigaunt|
|Headcrabs||Headcrab · Fast Headcrab · Gonarch · Lamarr · Poison Headcrab · Standard Headcrab · Headcrab Shell|
|Zombies||Zombie · Fast Zombie · Gonome · Poison Zombie · Standard Zombie · Zombine|
|Vortigaunts||Vortigaunt · Vortigese · All-Knowing Vortigaunt · R-4913 and X-8973 · Sweepy · Uriah · Victory Mine Vortigaunt · Vortigaunt Camp · Vortigaunt Shepherd|
|Flora and minerals||Crystal · Fungus · Healing Pool · Light Stalk · Trampoline · Tree|
|Weapons||Ceiling Turret · Hivehand · Sentry Cannon · Snark · Snark Mine|
|Technology||Healing Shower · Thumper|
|Creatures (cut)||Archer · Charger · Fast Walker · Flocking Floater · Kingpin · Mr. Friendly · Panther Eye · Sand Barnacle · Snapbug · Stukabat|
|Weapons (cut)||Black Hole Gun|