As a soldier sent in to eliminate Gordon Freeman, you are separated from your base unit and discover a new alien race amidst the chaos. It’s quickly revealed that these highly advanced alien life forms descended upon Earth to pillage the planet from the Black Mesa facility when Gordon Freeman transported to the border world of Xen.

Although you were originally sent into Black Mesa to silence Freeman and his fellow scientists in the facility, you now find yourself stranded and confused–battling fierce new alien creatures and a variety of other foes in an effort to save your own life.

In Half-Life: Opposing Force, Gearbox redefined what an action game expansion should be. Named PC Game of the Year by the Academy of Interactive Arts and Sciences, Opposing Force offers an unprecedented amount of new content and gameplay while expanding upon the thrilling Half-Life story.