Half-Life 2: Episode Three

Half-Life 2: Episode Three is a canceled first-person shooter in the Half-Life series. It would have followed Half-Life 2: Episode Two as the final instalment in the trilogy of episodes that extended the story of Half-Life 2. Although it was announced in May 2006 that the trilogy would conclude by Christmas 2007, Episode Three never materialized.

Although story details remained tightly under wraps, concept art indicated that the game would see Gordon Freeman and Alyx Vance traveling to the Arctic to find the Borealis, the icebreaker glimpsed in Episode Two which was said to contain a powerful technology that could be used against the Combine. The player would have had access to several new weapons, including an Ice Gun which could freeze enemies and create walls of ice, and (according to code leaked in Dota 2), a flamethrower. One new enemy was a blob creature which could change its shape and consume other enemies.

As the team missed the Christmas 2007 deadline and 2008 came around, Episode Three remained in the early stages of production, with the team struggling to find ways to innovate the gameplay within the confines of the aging Source engine. As a new engine, Source 2, began to take shape, Episode Three was canceled in favor of a full-fledged sequel to Half-Life 2: Half-Life 3.

In 2020, Valve released Half-Life: Alyx, a prequel to Half-Life 2 that resolved Episode Two's cliffhanger. The interactive book The Final Hours of Half-Life: Alyx revealed that Episode Three had been canceled in favor of Half-Life 3, and in 2024, gameplay footage of Episode Three was shown for the first time in Half-Life 2's 20th Anniversary Documentary.