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This subject is from the Black Mesa Incident era.This is a featured article.

"I don't know! I've never seen that species before!"
Black Mesa Scientist[src]

Race X[3] is the designation given to a mysterious alien species (or collection of species) that appeared in the Black Mesa Research Facility late in the Black Mesa Incident.

The aliens of Race X serve as the main antagonists for Opposing Force.


Sprites coming from a Race X Xen crystal-powered portal on Xen.

Race X consists of several alien species, varying widely in size and shape. Their technology appears almost entirely biological in nature; notably, they use living weapons such as the insectoid Shock Roach, In addition, they also use massive anomalous creatures known as Gene Worm(s) to terraform uninhabitable areas for their race. These aliens also have a variety of natural defenses, such as claws, spines, and toxic saliva.

Race X appears to have mastered teleportation technology, as they can teleport around Black Mesa and have installed at least one Xen crystal-powered teleportation device on Xen. Their portals are typically purple in color, as opposed to the green-glowing portals seen used by Xen residents, though the significance of this difference in colors have yet to be fully explained. They used the Xen teleporter during the later stages of the Black Mesa Incident to bring Sprites from their homeworld to Earth, this suggests they already had some knowledge of Xen prior to the invasion. However, they were not particularly well adapted to the Borderworld,[4] and, as a result, have never had a notable presence there.

Race X was discovered by chance by Black Mesa scientists when they opened a rift to another dimension than that of Xen during their portal technology experiments,[2] which lay "Somewhere beyond Xen".[4] As the nature and location of the dimension was largely unknown, the designation "X" was used by Black Mesa to refer to the dimension and its inhabitants.[2]

The aliens of Race X have no relation to those of Xen, and as such did not cooperate with them during the Black Mesa Incident. The Resonance Cascade probably affected portals linked to their world, allowing them to teleport into the Black Mesa facility in great numbers; Some apparently teleported into Xen as well. They might also have used the Gene Worm portal, which may have been the original portal to the Race X homeworld in Black Mesa.

Upon their arrival at Black Mesa, the smaller Race X troops begin killing any living beings in the vicinity to make way for the Gene Worm. Their eventual goal was to assimilate Earth's natural resources through the use of the Worm;[3] their plans were stopped, however, due to the actions of Adrian Shephard. Afterwards, it is likely that the rift to their dimension was sealed off by Black Mesa's destruction, removing their only access point to Earth and preventing them from spreading across the planet.

Some of the Race X creatures are studied in Black Mesa's Sector E Biodome Complex. A huge Sprite-powered portal used by the Gene Worm is also present in Black Mesa. Not all Black Mesa scientists are aware of Race X's existence, as suggested when a scientist attacked by a Shock Trooper calls out that he has "never seen that species before".

Known Species

The Gene Worm coming through its portal.

Behind the scenes

Created by Gearbox, the Race X only appears in Opposing Force; they are not mentioned in any other licensed games or media.

Some explanation and clarifications about the Race X and their place in the Half-Life universe were given by series' writer Marc Laidlaw; it can be found in the Marc Laidlaw Vault on the HalfLife2.net Forums. There he states that Race X is purely a Gearbox creation that does not figure at all in his thinking about the Half-Life universe (although his level of input into its creation, if any, is unknown). He furthers adds that the Gearbox team wanted to come up with a set of creatures that would create gameplay they knew how to make, and that they could have been making an original title or an add-on for any other franchise, and plugged Race X into it - the reason being that they had gameplay they wanted to explore and needed the freedom of their own race of critters to conduct those experiments with. He also suggests that if Gearbox had kept making games set in the Half-Life universe, more about the Race X would have been revealed.[4]

Race X's creator Stephen Bahl gave further information about the Race X's creation, nature and purpose when asked on Facebook. Bahl states that the team wanted to add some new creature variety without messing with what Valve had already established, hence the creation of another rift to another dimension, allowing the coming to Earth of creatures unrelated to Nihilanth's issues with its race and the Combine, and not interfering with Marc Laidlaw's original plot. To the team, "it made sense that a rift to a dimension other than Xen could have opened up to let other creatures in".[2]

Shock Troopers inherit the same artificial intelligence behavior and tactics used by the HECU Marines from the original Half-Life. They were modified to not attack the aliens from Xen. However, they will still attack Alien Grunts and Gargantuas on sight. This is believed to be an error in the code as the developers did not disable the Marines "nemesis" function which overrides their AI. This function makes Shock Troopers ignore the player and solely target their specified nemeses, in this case the ones attributed to the Marines.


List of appearances


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