"Half-Life: Blue Shift" is the second Expansion for Half-Life, which was also made by Gearbox Software, and was released on June 12, 2001. "Half-Life: Blue Shift" happens during the same time as Half-Life and in the same setting, just like "Opposing Force." In this expansion, you play as Barney Calhoun, a security guard who works at Black Mesa during the resonance cascade. 