Guide to the Half-Life Series

(I originally wrote this guide to the Half-Life series in mid-2020, following the release of both Half-Life: Alyx and Black Mesa. Unfortunately, it's still largely up to date as of January 2025.)

Core Games

• Half-Life: First game in the Half-Life series. Follows Dr. Gordon Freeman, a 27 year old MIT Graduate, as he fights his way across the Black Mesa Research Facility after an unforeseen disaster causes aliens to invade the facility.
• Half-Life 2: Sequel to Half-Life, set 20 years after the original game. Gordon Freeman returns to find the Earth has been enslaved by an oppressive alien regime known as the Combine, leading him to join the human resistance in fighting to win humanity's freedom back from their alien oppressors.
• Half-Life 2: Episode 1: Direct sequel to Half-Life 2. Continues Gordon's story immediately after the end of Half-Life 2.
• Half-Life 2: Episode 2: Direct sequel to Half-Life 2: Episode 1. Once again continues Gordon Freeman's story in the world of Half-Life 2 following the events of Episode 1.
• Half-Life: Alyx: VR-exclusive Interquel set 5 years prior to Half-Life 2 and its episodes. Follows Alyx Vance, daughter of resistance leader Eli Vance and future ally of Gordon Freeman, as she and the fledgling resistance uncover a powerful Combine secret.

Gearbox Spin-Offs

• Half-Life: Opposing Force: Occurs simultaneously with Half-Life. Follows Adrian Shepard, a US Marine sent to Black Mesa to cover up the disaster and subsequent alien invasion. While some events from Opposing Force are considered canon, Adrian Shepard is never seen again and the events of the game's story are never referenced.
• Half-Life: Blue Shift: Occurs simultaneously with Half-Life as well. Follows Barney Calhoun, a Black Mesa security guard and friend of Gordon Freeman, as he tries to escape from Black Mesa following the disaster. Barney Calhoun returns in Half-Life 2, though the events of Blue Shift are never mentioned.
• Half-Life: Decay: Also occurs simultaneously with Half-Life. A two player co-operative game that follows Gina Cross and Colette Green, two of Gordon Freeman's co-workers, as they attempt to assist Gordon as he fights to stop the alien invasion. Originally released exclusively for PS2, though a fan-made PC port has since been made available.

Demos

• Half-Life: Day One: Privately released demo of Half-Life, effectively just the first five chapters of Half-Life from a slightly earlier stage in development than the full game.
• Half-Life: Uplink: Official demo of Half-Life based loosely on a segment cut from the final game.
• Half-Life 2: Lost Coast: Tech demo based on a segment cut from Half-Life 2, originally designed to test HDR lighting effects within the Source Engine.

Other Games

• Half-Life: Source: Port of Half-Life to the Source Engine. Features several minor graphical enhancements over the original, but is also plagued with several major bugs not present in the original as well.
• Half-Life 2 Deathmatch: Competitive online multiplayer game based on Half-Life 2. Serves as a successor to Half-Life's own online multiplayer mode.
• Half-Life Deathmatch Source: Remake of Half-Life's online multiplayer mode in the Source Engine. Shares many of the graphical enhancements and bugs also seen in Half-Life: Source.
• Half-Life 2 Survivor: Japan-exclusive competitive arcade game based on Half-Life 2. A fan-made PC port has been released online, albeit with various missing features due to the discontinuation of the game's online services.
• Portal: First person puzzle/platformer set within the Half-Life universe. Features several references to characters and events from Half-Life and Half-Life 2.
• Portal 2: Direct sequel to Portal, featuring additional references to Half-Life and its sequels.
• Counter-Strike: Originally released as an expansion for Half-Life under the name Half-Life: Counter-Strike. First game in the Counter-Strike series, a series of team-based tactical shooters also developed by Valve.
• LEGO Dimensions: Toys-to-life action-platformer game featuring characters and locations from various well known franchises. Most notably includes a large amount of content based on the Portal series of games, which includes various references to the Half-Life series.

Books and Stories

• The Final Hours of Half-Life: Extensive article about the development of the first Half-Life, written by gaming journalist Geoff Keighley. Was followed by a series of similar articles and books, also written by Keighley, about the development of Half-Life 2, Portal 2 and Half-Life: Alyx.
• Half-Life 2: Raising the Bar: Extensive guidebook produced by Prima Games, detailing the history, development and content of various Valve Software games, with heavy emphasis on Half-Life 2 and the Half-Life series as a whole.
• Epistle 3: Narrative by series writer Marc Laidlaw detailing the events that would have occurred in his original plan for Half-Life 2: Episode 3 prior to his departure from Valve. All major characters and locations are given gender-reversed codenames to mask their relation to the Half-Life series.

Notable Fan Projects

• Black Mesa: Remake and partial re-imagining of Half-Life in the Source Engine, developed by a team of fans known as the Crowbar Collective rather than Valve Software. Launched as a mod in 2012, was released as a retail product on Steam Early Access in 2015, and finally left Early Access in early 2020.
• Guard Duty: Fan-made remake of Half-Life: Blue Shift in the Source Engine, developed independently of Black Mesa by a team known as Tripmine Studios. Currently in development.
• Operation: Black Mesa: Fan-made remake of Half-Life: Opposing Force in the Source Engine, also developed by Tripmine Studios. In development simultaneously with Guard Duty.
• Peer Review: Fan-made remake of Half-Life: Decay in the Source Engine, developed independently from both Black Mesa and the Tripmine Studios remakes by a team known as PSR Digital. Currently in development.
• Project Borealis: Fan-made sequel to Half-Life 2: Episode 2, made in Unity. Intended to serve as a finale to the currently unfinished Half-Life 2 storyline, based on Marc Laidlaw's Epistle 3 narrative. Currently in development.
• Boreal Alyph: Alternate fan-made sequel to Half-Life 2: Episode 2 made in the Source Engine with original assets. Like Project Borealis, it is also inspired by Epistle 3. Currently in development.
• Codename: Gordon: Also known as Half-Life 2D. 2D action-platformer loosely based on Half-Life 2. Known for being one of the first fan projects to receive a release on Steam. No longer officially available since its official website has shut down.
• Hunt Down the Freeman: Fan-made game intended to serve as a spiritual successor to Half-Life: Opposing Force, following ex-marine Sergent Mitchell as he attempts to hunt down Gordon Freeman. Was made available as a retail product on Steam, despite being notorious for being severely buggy and its overall abysmal quality. It was frequently used as an example of how Valve no longer cared about the Half-Life franchise, prior to the announcement of Half-Life: Alyx.

Canceled Titles

• Half-Life 2: Episode 3: Planned direct sequel to Half-Life 2: Episode 2 which would have concluded Gordon Freeman's story in the world of Half-Life 2. Originally planned to release in 2008, its unofficial cancellation resulted in a 12 year hiatus for the Half-Life series until Half-Life: Alyx was officially confirmed in late 2019.
• Half-Life 2: Episode 4: Also referred to as Return to Ravenholm. Would have been a side game in the Half-Life 2 universe centered around the town of Ravenholm, following a new character rather than Gordon Freeman. Was originally in development by Warren Spector and Junction Point studios in 2005, before being passed to Arkane Studios in 2006 who worked on it until its cancellation in 2007. The project was never officially announced, and its existence was only discovered following a data breach at Arkane Studios in 2011.