Race X consists of several alien species, varying widely in size and. The aliens of Race X serve as the main antagonists for Opposing Force. Valve’s debut title wins more than 50 game-of-the-year awards on its way to being named “Best PC Game Ever” by PC Gamer, and launches a franchise with more than eight million retail units sold worldwide. 'I don't know I've never seen that species before' Black Mesa Scientistsrc Race X 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. HALF-LIFE sends a shock through the game industry with its combination of pounding action and continuous, immersive storytelling.