Half-Life: Blue Shift (a play on the physical phenomenon of the same name) is the second, but stand-alone expansion pack for the first-person shooter computer game Half-Life, developed by Gearbox Software and released on June 12, 2001. Like Gearbox's other expansions, Half-Life: Opposing Force and Half-Life: Decay, Blue Shift returns to the setting and timeline of the original story, but with a different player character: the ubiquitous Black Mesa Research Facility security guard Barney Calhoun. As Barney, the player attempts to escape the alien invasion caused by the resonance cascade and the ensuing military cover-up.
Blue Shift has now been released via Valve's content delivery service, Steam, and can be purchased individually or in a pack with several other Half-Life titles. A third-party remake of Blue Shift for Source is under development.
Blue Shift started out first as an exclusive part of the Half-Life Sega Dreamcast port. Due to Sega pulling the plug on the Dreamcast, this version was canceled only weeks away from release (the Dreamcast Half-Life port has since been leaked onto the Internet, with both Half-Life and Blue Shift fully playable). Gearbox then turned the project into a stand-alone product; unlike Opposing Force, it does not require the original Half-Life.
Although fans of Half-Life were eager to play more of their beloved game, many complained that Blue Shift did not measure up to the high standards set by the Opposing Force expansion. The game offers some new levels and areas of Black Mesa previously unseen in a (relatively short) new campaign, but no new weapons or enemies, as Opposing Force offered. Aside from the High Definition pack, the only new content was a character named Dr. Rosenberg, a Black Mesa scientist who has his own unique character model and played a major role in the story, and alternate scientist and security guard models wearing civilian attire. Blue Shift reviews were poor in comparison to other games in the series.
On August 24, 2005, Blue Shift became available for download via the Steam content delivery program. Anyone who owned an old copy of Half-Life, or the Half-Life 2 silver or gold packages (thus, having access to the back catalog) could download it for free. Since then, free access to Valve's back catalog after registering a previously owned copy of Half-Life has been discontinued, and Blue Shift must now be bought either alone, as part of the Half-Life 1 Anthology, or as part of the Valve Complete Pack. The High Definition Pack is also available via Steam
However, the Steam port suffers from numerous issues, most probably because the GoldSrc engine used in the game has been changed, preventing Blue Shift maps from being correctly played. Additionally, the Steam port omits the fixes from the Blue Shift patch that prevent known map and model glitches. The Steam port also introduced several other bugs that did not exist in the original release, such as the GUI color now being displayed in the standard Half-Life orange, not Blue Shift blue. A third-party mod, Blue Shift Unlocked, addresses these issues and can successfully patch files from either a CD or Steam version of Blue Shift.
The remainder of the game takes place in an abandoned walled-up sector of the base, originally built for research into teleportation (prior to the construction of the Lambda Complex). Calhoun, Rosenberg, and two other scientists (Walter Bennet and Simmons) try to restart the prototype teleporter. Calhoun is briefly teleported to a ruined human research camp on Xen to enable a triangulation device and allow the teleporter to be targeted. Upon his return, Calhoun is charged with replacing the teleporter's burnt-out batteries, then fights off Marines and aliens while the three scientists teleport out of the facility. Calhoun experiences a brief malfunction while teleporting: he is quickly "zapped" through different locations across Black Mesa and is imbued with a green glow. Finally, he returns safely to the remote facility entrance where he and the three scientists escape in a Black Mesa SUV. Similar to every other game in the series, Blue Shift ends with a screen displaying the main subject name and their status as of the events after the game.
At several points during Blue Shift, Calhoun almost meets the protagonist of Half-Life, Gordon Freeman: Calhoun is locked outside the door to Area 3 Security Facilities and sees Freeman go past on the tram heading towards Sector C (thus confirming that the security guard Gordon sees in the beginning of Half-Life is in fact Barney); using remote cameras, Calhoun also sees Freeman heading towards the H.E.V. Storage Area from the surveillance room; during the ending sequence of Blue Shift, Calhoun sees an unconscious Freeman being dragged by H.E.C.U. soldiers towards a trash compactor.
Correlating the Blue Shift timeline with the other games is fairly easy; it begins slightly before Half-Life, as shortly after starting the game Calhoun sees Freeman moving past him in the transit system during the opening credits of Half-Life, and ends before the nuclear explosion which finally destroys Black Mesa during the epilogue of Opposing Force. Towards the end of Blue Shift, when Barney is jumping randomly between locations after teleporting, Gordon Freeman can be seen being dragged by the H.E.C.U soldiers, an event which occurs halfway through the first game, suggesting that Blue Shift ends somewhat early in the Half Life timeline.
Blue Shift is the shortest game in the original Half-Life series, with all the events taking place alongside a measurable fraction of those in the first game. Blue Shift is also arguably the most disturbing—as most of the events take place on the surface in the immediate aftermath of the disaster, the player sees firsthand the panic of the Black Mesa personnel as they desperately try to flee the facility by any means necessary. It is interesting to note that aside from the PlayStation 2-only Decay, Blue Shift is arguably the only Half-Life game with a "happy ending". At the end of Half-Life, Gordon Freeman is conscripted by the mysterious G-Man, and Opposing Force's Adrian Shephard is indefinitely detained by the same individual to ensure his silence. However, in Blue Shift, Barney and his three scientist companions escape Black Mesa and the scrutiny of the G-Man, whose brief report suggests he deems them, perhaps out of pride and annoyance, too insignificant to actively monitor or eliminate them. Speculation of the G-Man's role in the Half-Life series would even suggest that he may in some way be aware of Barney's significant role in the events of Half-Life 2, although most people believe that he doesn't care about him, since you only see him once in this game.