Half-Life: Blue Shift is an expansion pack for Valve Software's science fiction first-person shooter video game Half-Life. The game was developed by Gearbox Software with Valve Corporation and published by Sierra Entertainment on June 12, 2001. (It was originally set for release in Spring.) Blue Shift is the second expansion for Half-Life, originally intended as part of a Dreamcast version of the original game. Although the Dreamcast port was later cancelled, the PC version continued development and was released as a standalone product. The game was released on Steam on August 24, 2005.