Half-Life: Blue Shift

Half-Life: Blue Shift is an expansion pack for the game Half-Life. It was made by Gearbox Software with Valve and published by Sierra Entertainment. Blue Shift was the second expansion for Half-Life, originally intended as part of a port of Half-Life. Although the port was cancelled, the Windows version was published as a standalone product in 2001 for Windows. It was published on Steam on August 24, 2005. The name is a pun on blue shift, a science term, and the fact that the player is on duty as a blue-wearing security guard.

As with Gearbox's previous expansion pack, Opposing Force, Blue Shift returns to the events of Half-Life, but portrays the story through the perspective of someone else. You play as security guard Barney Calhoun, hired by the Black Mesa Research Facility, who must fight his way to safety during an incident. Blue Shift also includes a pack that upgrades the Half-Life models and textures.

Blue Shift received both good and bad reviews. Many reviewers were critical of the short length and lack of new content, although the new graphics were praised.