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)