| Half-Life 2: Episode Three | |
|---|---|
 Concept art depicting the Borealis | |
| Developer(s) | Valve Corporation |
| Publisher(s) | Valve Corporation |
| Writer(s) | Marc Laidlaw |
| Series | Half-Life |
| Engine | Source |
| Release | Canceled |
| Genre(s) | First-person shooter |
| Mode(s) | Single-player |
Half-Life 2: Episode Three is a canceled first-person shooter game developed by Valve. It was planned as the last in a trilogy of episodic games continuing the story of Half-Life 2 (2004). Valve announced Episode Three in May 2006, with a release planned for 2007. Following the cliffhanger ending of Episode Two (2007), it was widely anticipated.
Episode Three was to be set in the Arctic and introduce elements such as an ice gun and a blob-like enemy. Marc Laidlaw, the writer for the Half-Life series, said he intended it to end the Half-Life 2 story arc. Valve released little information over the following years, and in 2011 Wired described it as vaporware. Valve eventually canceled it, citing a lack of direction and the limitations of the episodic format. They delayed development of a new Half-Life until their new game engine, Source 2, was complete.
Laidlaw left Valve in 2016. In 2017, he released a short story that journalists speculated was a summary of the Episode Three plot. It followed the Half-Life protagonist, Gordon Freeman, as he journeyed to the Arctic and boarded the Borealis, an experimental vessel created by Aperture Science. After Laidlaw posted the story, fans launched several projects attempting to recreate Episode Three. After canceling several further Half-Life games, Valve released a virtual reality game, Half-Life: Alyx, in 2020.