Half-Life, the first game in the series, takes place at the fictional Black Mesa Research Facility in New Mexico circa the turn of the 21st century. Gordon Freeman, a theoretical physicist, is involved in an experiment that accidentally creates a dimensional rift to a trans-dimensional world called Xen, causing extraterrestrial life to swarm the facility and kill the survivors. As Freeman and the survivors try to flee, a Marine Recon unit is brought in to contain the situation, including killing those that try to escape. Freeman ultimately makes his way to Xen and eliminates the alien "leader", the Nihilanth, but then is confronted by the G-Man, who places Freeman into stasis. Half-Life: Opposing Force follows Recon soldier Adrian Shephard as he helps to quell another alien invasion within the Black Mesa facility. Within Half-Life: Blue Shift, Black Mesa security worker Barney Calhoun works to escape the facility from both alien forces and the Recon soldiers with Dr. Rosenberg and two other scientists.
Half-Life 2 starts about twenty years following the first game. With the death of the Nihilanth, the Black Mesa dimensional rift grew out of control, creating portal storms across Earth and further spread of alien creatures. These drew the attention of the technically-advanced alien force called the Combine that conquered Earth within seven hours, subjugating humanity to its control through mind-controlling transmissions that suppress their urge to fight back. Surviving humans now are forced to live in former cities converted to interment camps and patrolled by the Combine and humans that have allied with them. G-Man wakes Freeman up to this new world, sending him to City 17. Freeman quickly regroups with members of the human resistance including former Black Mesa workers Barney Calhoun, Isaac Kleiner, and Eli Vance along with Eli's daughter Alyx Vance and her robotic pet D0g. Freeman is targeted as a threat by the Combine, but with his allies' help along with that of the alien Vortigaunt species, Freeman and Alyx are able make his way into the Citadel, a gigantic tower in City 17 from which the Combine operate and send out their mind-controlling transmissions. They confront Wallace Breen, the human spokesman for the Combine, and attempts to destroy the Citadel by initiating the destruction of its dark energy reactor.
Within Half-Life 2: Episode One, the destruction of the Citadel's reactor has started a chain reaction that will take all of City 17 with it. Aided in part by the G-Man and the Vortigaunt, Freeman and Alyx escape the primary explosions and work to try to slow the reaction, giving the surviving humans the time needed to escape the city. However, they find that the Combine are attempting to accelerate the process, in part to alert the off-world Combine forces to their plight. Freeman and his allies safely make their way out of City 17 in time. In Half-Life 2: Episode Two, the massive explosion has created a superportal which could allow the full Combine force onto Earth. G-Man provides Freeman with the appropriate information on how to close the portal, as well as the location of the Borealis, a ship used by Aperture Science used to test humanity's own version of portal technology. Freeman and his allies help to secure safety for the human survivors from City 17, and launch a satellite to shut down the superportal in time. Just as they are about to set off to locate the Borealis, a Combine Advisor appears and kills Eli, leaving Alyx in tears.
The Half-Life series includes a core set of titles which carry the main storyline. These games were released in chronological order, either portraying the events of one game from the perspective of a different character, or following on from the events that are depicted in the previous title. As of May 2010, the main series consists of the original video game and its sequel, as well as three expansion packs and two episodic games. A third episodic game remains in development. In addition, several spin-off titles have been released. These vary in nature, consisting of an arcade game, technology demonstration, and a series of puzzle games. The original game and its expansions all use Valve's GoldSrc game engine, a heavily modified Quake engine. The later games accompanying the sequel all use Valve's proprietary Source engine.
Half-Life is the first game in the series, and was the debut title of Valve Software. First released on November 19, 1998, Half-Life follows Gordon Freeman, a theoretical physicist, after the Black Mesa Research Facility accidentally causes a dimensional rift which allows the facility to be invaded by aliens. Freeman consequently attempts to survive the slaughter and resolve the situation. The game was originally published by Sierra Studios and released for Windows, although Gearbox Software would later port the game to PlayStation 2 in 2001. Valve themselves later converted the game to use their Source engine. Half-Life received critical acclaim upon release, critics hailing its overall presentation and numerous scripted sequences. The game won over 50 Game of the Year awards and its gameplay has influenced first-person shooters for years to come. Half-Life has since been regarded as one of the greatest games of all time.
Half-Life was followed by an expansion pack, Half-Life: Opposing Force, on November 1, 1999. Unlike Half-Life, Opposing Force was developed by Gearbox Software, although it was still published by Sierra Studios. Opposing Force was first announced as a mission pack for Half-Life in April 1999, and was released for the Windows version of the game. The player no longer assumes the role of Gordon Freeman, but rather sees the later events of the first game from the perspective of a US Marine corporal, Adrian Shephard. Shephard is initially assigned to cover up the events at Black Mesa, but is soon left isolated and has to fight to survive against a new group of alien invaders and black operations units. Opposing Force was received favorably by critics, many citing the game as being as influential on setting expansion pack standards as the original game had been in influencing the overall genre. The game won the Computer Game of the Year Interactive Achievement Award of 2000 from the Academy of Interactive Arts & Sciences.
Gearbox later went on to develop Half-Life: Blue Shift, Half-Life's second expansion pack. Like Opposing Force, Blue Shift was published by Sierra Entertainment. Announced in 2000, the game was initially developed as an add-on for a Dreamcast port of Half-Life; however, the port was cancelled and Blue Shift was instead released for Windows on June 12, 2001. Blue Shift puts the player in the position of Barney Calhoun, a security guard working at Black Mesa. The game takes place within the early parts of Half-Life, with Calhoun attempting to escape the facility with a small group of scientists. Blue Shift also includes a High Definition pack, which upgrades the quality of the models and textures in both Blue Shift and the preceding games in the series. Critics gave Blue Shift a mixed but favorable reception, praising the game's atmosphere and the inclusion of the High Definition pack, but criticizing the otherwise lack of new content and short length of the story.
The third and final expansion for Half-Life was Half-Life: Decay. The game was again developed by Gearbox and published by Sierra. However, unlike previous titles, Decay is only available with the PlayStation 2 version of Half-Life. Decay is unique within the Half-Life series as the only cooperative game—two players must work together to progress through the game. Decay focuses on two of Freeman's colleagues, Gina Cross and Colette Green, as the two work with other scientists to counter the effects of the dimensional rift and ultimately attempt to close it. Released on November 14, 2001, Decay received a weak but overall positive reception from critics, many reviewers stating that it was fun to play through with a friend, but that the game's more puzzle-oriented gameplay detracted from the overall experience. An unofficial Windows port of the game was released in September 2008.
On November 16, 2004, Valve released Half-Life 2, the sequel to the original game. The game had a six-year development cycle, which saw several delays and the leak of the game's source code. Half-Life 2 returns the player to the role of Gordon Freeman. Set twenty years after the original game, Earth has been occupied by the Combine, a transdimensional race that exploited the events of the first game to invade. The G-Man inserts Freeman into City 17 in Eastern Europe to combat the Combine occupation. Half-Life 2 garnered near-unanimous positive reviews and received critical acclaim much like its predecessor, winning over 35 Game of the Year awards for 2004. Considered one of the greatest video games of all time, the game has been critically praised for its advances in computer animation, sound, narration, computer graphics, artificial intelligence, and physics. Half-Life 2 was the first title to use Valve's Steam content delivery system, a system that eventually led to Valve falling out with publisher Sierra Entertainment.
Following Half-Life 2, the series was continued using a pair of episodic games, with a third planned. Half-Life 2: Episode One was the first of these, set around City 17 after the events of the original game, in which Freeman and Alyx Vance must attempt to escape the city after a dark energy reactor core they damaged at the end of Half-Life 2 threatens to destroy the city. It was released on June 1, 2006, and introduced several new graphical effects including new lighting features and more advanced facial animation. Episode One received a generally positive critical reaction, although the game's short length was a point of common criticism.
The second episodic game, Half-Life 2: Episode Two, continues the story from where Episode One ended. It was released on October 10, 2007, bundled with the games Portal and Team Fortress 2 as well as Half-Life 2 and Episode One in the package The Orange Box, which was released for Windows PCs and the Xbox 360 and PlayStation 3 consoles. The game was again developed by Valve, and distributed using both Steam and Electronic Arts. Continuing with Valve's policy of orienting each episode around a particular theme or set of technologies, Episode Two focuses on expansive environments, travel and less linear play. As Gordon Freeman, the player travels with Alyx Vance away from the ruins of City 17 into the surrounding countryside, pursued by Combine forces. Episode Two's new technologies and gameplay features were praised by reviewers; however, though it was significantly longer than Episode 1, the short length of the game was again a point of criticism.
Half-Life 2: Episode Three is announced as the third and final installment in the series of episodic expansions. It is planned as the last episode in the story arc, but Valve has stated it will not be the end of the entire Half-Life franchise. Some concept art has surfaced as well as the possible incorporation of sign language into the game by including a deaf character. In a March 2010 interview, Newell spoke of "broadening the emotional palette" of the series, and how the next Half-Life game may return to "genuinely scaring the player". In a May 9, 2011, interview with Develop magazine, Newell commented on the episodic release model, saying, "We went through the episodes phase, and now we’re going towards shorter and even shorter cycles," adding, "For me, ‘entertainment as a service’ is a clear distillation of the episodic content model." Due to the large number of delays in its production to the point where Valve employees have refused to comment on the release, Episode Three has become one of video gaming's most infamous cases of vaporware.
Return to Ravenholm, sometimes referred to as Half-Life 2: Episode Four, was being developed by Arkane Studios before being cancelled. The episode would have featured the town of Ravenholm and involved headcrabs and zombies, but due to taking place before the end of Half-Life 2: Episode Two, Valve felt it would be constrained creatively.
Another abandoned episode was being developed by Junction Point Studios, and would have featured a magnet gun. However, Warren Spector stated that the studio's direction shifted to working on Disney's Epic Mickey, and the project was dropped.
The Portal series, which takes place in the same universe as the Half-Life games, is a series of puzzle games developed by Valve Corporation. The first game in the series, Portal, was initially released alongside Episode Two in The Orange Box on October 10, 2007. The player controls a test subject named Chell as she moves through the laboratories of Black Mesa's primary rival, Aperture Science, completing various tests with a device that allows her to create linked portals in physical space. In the later stages of the game, the player battles GLaDOS, a corrupt artificial intelligence computer that monitors her every move. The game is the spiritual successor to Narbacular Drop, with many of the same team members working on the game. Portal has been acclaimed as one of the most original games in 2007, receiving praise for its unique gameplay and darkly humorous story. An Xbox Live Arcade expansion was released on October 22, 2008, and its sequel, Portal 2, was released on April 19, 2011.
Half-Life 2: Lost Coast is a technology demonstration, developed by Valve to display new high dynamic range rendering and a variety of other features. Valve asked for feedback as to whether these features should be used in their future games. The level was designed with a variety of appropriate environments to emphasize these effects. Consisting of a single map, Lost Coast was originally to be part of Half-Life 2, but was dropped during development. The game follows Gordon Freeman as he travels up a coastal cliff to destroy a Combine artillery launcher in a monastery, which is firing on the town of St. Olga. Released over Steam on October 27, 2005, the level received a generally positive reception, and there was consensus among fans that the new features should be implemented into future games released by Valve.
The success of the Half-Life series has spurred the creation of several spin-off games for Half-Life 2. Codename: Gordon is a two-dimensional Flash sidescroller shooter developed by Nuclearvision Entertainment, and was released over Valve's Steam online delivery system on May 16, 2004, as a promotional game for the then-upcoming Half-Life 2. The developer has since gone bankrupt, but the game itself can still be installed via a direct link to Steam, despite not being listed in the store. Codename: Gordon was well received by reviewers and the public, and attracted over 600,000 players in the first three weeks after its release. Reviewers praised the game for its gameplay and unique dialog style, but also criticized it for its improper optimization, and lack of opponent variety.
Characters from Half-Life have appeared in other titles. Peggle Extreme, a special edition of Peggle bundled with the PC version of The Orange Box features levels based on Half-Life 2, Team Fortress 2 and Portal. The headcrab is also an unlockable character in Super Meat Boy when bought on Steam. The Headcrab also appeared in an April Fools event in the MMO Vindictus as an event item along with the Crowbar, possibly due to the game being created on the Source Engine as well. In the game Magicka there is a playable character (after the addition of a DLC), which closely resembles the original zombie from the Half-Life universe, equipped with a crowbar. Gordon also appears in Renegade Ops and the headcrab is available as a pet in Torchlight 2.
The video game development company behind the Half-Life series, Valve Corporation, was founded in 1996 in Kirkland, Washington by former Microsoft employees Mike Harrington and Gabe Newell. Valve began working on the first game of the series soon after the company's formation, and settled on a concept for a horror-themed 3D action game, using the Quake engine as licensed by id Software. The game was a hit at the 1997 E3 convention, where its animation system and artificial intelligence were demonstrated. The game's success led to its first expansion pack, Half-Life: Opposing Force, which was developed by Gearbox Software, a then-new company based in Plano, Texas, and announced on April 15, 1999. Gearbox founder Randy Pitchford said in an interview that he believed Valve gave them the opportunity to produce a sequel to Half-Life to allow Valve to focus on future titles. The game was demonstrated at the 1999 E3 convention, where new locations, characters, and the story were revealed.
The second Half-Life expansion pack, Half-Life: Blue Shift, was again developed by Gearbox Software and announced by its publisher, Sierra Entertainment, on August 30, 2000. Sierra intended to release Blue Shift for the Dreamcast, and it was set to include higher detail models and textures that were double the polygon count of the models from Half-Life. However, after several months of delays, Sierra terminated development on the Dreamcast version of Blue Shift on June 16, 2001, and the company instead released Blue Shift for the PC on June 12, 2001. Afterward, Gearbox began working on a Half-Life game for the PlayStation 2. The game, titled Decay, was showcased at E3 2001, where Gearbox demonstrated the game's use of new model sets, which were around twice as detailed as those in Blue Shift.
For several years, Valve secretly worked on the sequel to the original Half-Life, titled Half-Life 2. For the game, Valve developed a new game engine called the Source engine, which handles the game's visual, audio, and artificial intelligence elements. The Source engine comes packaged with a heavily modified version of the Havok physics engine that allows for an extra dimension of interactivity in both single-player and online environments. In the trilogy of episodic games that followed Half-Life 2, Valve made minor tweaks to the game's engine. In Half-Life 2: Episode One, Valve modified Alyx's AI to allow her to react to the player's actions because of her significant involvement in the game. The game runs on an upgraded version of Valve's proprietary Source engine, and features both the engine's advanced lighting effects, and a new version of its facial animation/expression technology.
On February 6, 2013, while speaking at the 2013 DICE conference about storytelling in games and film, J. J. Abrams and Gabe Newell announced that they had plans for a game and a film collaboration. Abrams said, "There's an idea we have for a game that we'd like to work with Valve on," while Newell said, "We're going to figure out if we can make a Portal movie or Half-Life movie together". In an interview in March 2016, Abrams stated that while he has been working on many other projects since, he still has plans to direct these films in the future, with both films in the writing stage.
A short film based upon Half-Life, titled Half-Life: Uplink, was developed by Cruise Control, a British marketing agency, and released on March 15, 1999. However, Sierra withdrew it from circulation after Sierra and Valve had failed to resolve licensing issues with Cruise Control over the film. The critical reception of the film was very poor. The film's plot was that of a journalist attempting to infiltrate the Black Mesa Research Facility and discover what was happening there.
In early 2009, the Purchase Brothers, a Toronto-based film company, released a five-minute film based on Half-Life 2: Episode One called Half-Life: Escape from City-17. The film combines live-action footage with 3D animation created using the Source SDK for the video game. It was well received by Valve. On August 25, 2010 they released a nearly 15 minute long part two. In late 2010 a trailer for a Half-Life inspired independent short film entitled Beyond Black Mesa was released. Directed by Brian Curtin, it follows the character Adrian Shephard. The full short film was released online on January 21, 2011.