List of Valve Corporation video games

Valve Corporation is an American video game developer and publisher founded in 1996 by Gabe Newell and Mike Harrington. The company is based in Bellevue, Washington. Valve's first game was Half-Life, a first-person shooter released in 1998. It received universal acclaim and sold over nine million retail copies. Alongside Half-Life's launch, Valve released development tools to enable the player community to create content and mods. The company then proceeded to hire the creators of popular mods, such as Counter-Strike, which became the most popular multiplayer first-person shooter for the next decade.

Valve continued their trend of developing predominantly first-person video games in the 2000s with a number of critically successful releases. In 2004, they released the highly anticipated sequel Half-Life 2 through their own digital distribution service Steam. The game sold over 10 million copies and was met with acclaim. Valve released two subsequent episodes for Half-Life 2 and later packaged those games together with the puzzle game Portal and the multiplayer shooter Team Fortress 2 in a collection known as The Orange Box. By the end of 2008, combined retail sales of the Half-Life series, Counter-Strike series and The Orange Box had surpassed 32 million units. Newell also projected that digital sales of Valve's games would eventually exceed retail sales as Steam continued to grow. In the late 2000s, Valve released two zombie-themed first-person shooters focusing on cooperative gameplay with the Left 4 Dead series. The company continued to release multiplayer games with the launches of Counter-Strike: Global Offensive and Dota 2, both of which have large esports communities fostered by Valve. During the 2010s, Valve began focusing on supporting their established multiplayer titles with regular content updates. In the late 2010s, Valve began investing in virtual reality and started to develop games and other software that make use of the technology.

Valve is considered to be one of the most important and influential companies in the gaming industry. The reception of their games, along with the creation of Steam, has prompted some publications to list Valve as one of the top game developers of all time, and the most powerful company in PC gaming. In 2013, Newell received a BAFTA Fellowship award with the BAFTA Games Committee recognizing the impact Valve had left on the gaming industry in producing critically and commercially successfully game franchises.

Cancelled games
Several games announced by Valve as being in development have since been put on hold indefinitely. In addition, details on a number of unannounced projects from Valve have been revealed or leaked long after their cancellation.
 * Prospero – A third-person, exploration game with a science fantasy theme. The project was in development at the same time as Half-Life. Prospero's development team transitioned to work on Half-Life, which had gained more traction.
 * Half-Life 2: Episode Three – Announced in 2006 with a tentative release date of late 2007, this game was supposed to continue the story from Half-Life 2: Episode Two. Episode Three missed its release date and Valve had stopped discussing the project by the early 2010s and has now been described as vaporware.
 * Half-Life 2: Episode Four – Also known as Return to Ravenholm, this project was in development by Arkane Studios around 2006–2007, however Valve decided not to take the project forward. In 2012, Valve writer Marc Laidlaw confirmed rumors surrounding the project's existence and screenshots of gameplay later emerged in 2013.
 * Untitled Half-Life 2 episode – In November 2005, Junction Point Studios announced that it was working with Valve on a game. In April 2015, Junction Point's founder Warren Spector revealed the project was an episode for Half-Life 2. Development on the game had ceased when Junction Point signed a deal with Disney Interactive Studios to develop Epic Mickey.
 * Untitled role-playing game – A fantasy, action role-playing game about fairies that was in a prototype phase and cancelled prior to Left 4 Dead release.
 * The Crossing – A first-person shooter developed in collaboration with Arkane Studios. The project was announced in 2007 and put on hold in May 2009.
 * Stars of Blood – A space pirate game. In November 2012, Newell revealed the project's name and confirmed that it was no longer in development.