Half-Life: Opposing Force

Half-Life: Opposing Force
Cover art, depicting the game's protagonist, Adrian Shephard
Developer(s)	Gearbox Software
Publisher(s)	Sierra Studios Valve (digital)
Director(s)	Randy Pitchford
Producer(s)	Randy Pitchford
Designer(s)	Rob Heironimus
Programmer(s)	John Faulkenbury
Artist(s)	Brian Martel
Writer(s)	Stephen Bahl Rob Heironimus Kristy Junio Randy Pitchford
Composer(s)	Chris Jensen
Series	Half-Life
Engine	GoldSrc
Platform(s)	Windows, OS X, Linux
Release	November 19, 1999 Windows NA: November 19, 1999 EU: December 3, 1999[1] OS X, Linux WW: July 31, 2013
Genre(s)	First-person shooter
Mode(s)	Single-player, multiplayer

Half-Life: Opposing Force is an expansion pack for the first-person shooter game Half-Life. It was developed by Gearbox Software and published by Sierra On-Line for Windows on November 19, 1999. Opposing Force was the first expansion for Half-Life and was announced in April 1999. Lead designer Randy Pitchford noted that he believed Gearbox was selected to develop Opposing Force because Valve, the creators of Half-Life, wanted to concentrate on their future projects. Over the course of development, Gearbox brought in a variety of talent from other areas of the video games industry to help bolster various aspects of design.

Opposing Force portrays the events of Half-Life from the perspective of a U.S. Marine, one of the enemy characters in the original, assigned to the Hazardous Environment Combat Unit (HECU). The player character, Adrian Shephard, is sent in to neutralize the Black Mesa Research Facility when a scientific mishap causes it to be invaded by aliens, but quickly finds that the Marines are outnumbered and slowly being beaten back by a second alien race and black operations units.

Opposing Force was received well by critics, with many describing it as the new benchmark title for expansion packs, in a similar fashion to how Half-Life revolutionized the first-person shooter genre. Other reviewers, however, thought that, despite its accomplishments, it still suffered from the negative aspects of other expansion packs.