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Half-Life: Day One is the initial pre-release demo of Half-Life.
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Period of time in which the original Half-Life held a primary focus.
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Half-Life is the first title for the series, and was the debut title of Valve Software.
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Half-Life: Uplink was a standalone demo set in the Half-Life universe, and contained levels and a storyline not found in the full title.
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Half-Life: Uplink is a short five-minute film loosely based on the events of Half-Life.
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Half-Life: Opposing Force is an expansion pack for Valve Software's science fiction first-person shooter video game Half-Life.
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Half-Life: Blue Shift, commonly referred to as Blue Shift, is the second stand-alone expansion pack for Half-Life
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Half-Life: Decay is an add-on included in the PlayStation 2 port of the first-person shooter game Half-Life, returning to the setting and timeline of the original story, but with different player characters: two female colleagues of Gordon Freeman, named Gina Cross and Colette Green.
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Codename: Gordon, also known as Half-Life 2D, is a side-scroller puzzle/action game.
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Half-Life 2 is a science fiction first-person shooter developed and published by Valve Corporation.
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Period of time in which tHalf-Life 2 held a primary focus.
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Half-Life 2: Deathmatch, often abbreviated as HL2:DM, is a multiplayer first-person shooter video game developed by Valve Corporation.
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Half-Life 2: Lost Coast is a technology demo showing off the Source engine's HDR rendering capabilities. The town of St. Olga, where the game is set, was originally slated to take place between the levels Highway 17 and Sandtraps, but was dropped.
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Half-Life 2: Episode One is the first of a trilogy[1] of expansion packs/episodes for the 2004 first-person shooter game, Half-Life 2.
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Half-Life 2: Survivor is an arcade game based on the science fiction first-person shooter video game, Half-Life 2.
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Half-Life 2: Episode Two is the second installment in a trilogy of episodes for the 2004 science fiction first-person shooter video game Half-Life 2, developed by Valve Corporation.
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Portal is a 2007 first-person puzzle-platform video game developed by Valve Corporation. The game was released in a bundle package called The Orange Box.
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Period of time in which The Orange Box's games held an equal focus.
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Portal: Still Alive is an Xbox 360 Live Arcade exclusive edition of Portal released on October 22, 2008. It features the original game, with various new levels and 9 new achievements.
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Half-Life: Escape from City 17 is a two-part Canadian short film written, developed, and filmed by the Purchase Brothers. The film is set in the Half-Life universe, during the events of Half-Life 2 and Half-Life 2: Episode One.
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The Portal ARG, or Alternate Reality Game, was introduced as an easter egg in the March 1 Patch. The notes released along with the patch read "Changed radio transmission frequency to comply with federal and state spectrum management regulations", and accompanying this was a new achievement, "Transmission Received".
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Beyond Black Mesa is a short independent fan film inspired by the Half-Life series.
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The PotatoFoolsDay ARG is the second alternate reality game (or ARG) created by Valve to promote Portal 2, following the original Portal ARG.
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Period of time in which Portal 2 held a primary focus.
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Portal 2 is a first-person puzzle video game developed and published by Valve Corporation.
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Peer Review is a free DLC made for Portal 2 aimed at expanding upon the co-op part of the game. It continues the story of ATLAS and P-body as they assist GLaDOS in finding a mysterious intruder in the facility through the Cooperative Testing Courses.
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Period of time in which little to no official content having to do with the Half-Life universe was released, much to the dissapointment of fans of the series.
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Black Mesa is a complete re-creation of the game Half-Life, utilizing the Source engine.
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Lamarr Goes to the Zoo is a side-scrolling platform game created by several Valve employees for a 48-hour game jam.
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