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 and published by Sierra Entertainment on June 12, 2001. 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.