Named Game of the Year by over 50 publications, Valve's debut title blends action and adventure with award-winning technology to create a frighteningly realistic world where players must think to survive. Also includes an exciting multiplayer mode that allows you to play against friends and enemies around the world.

A demo level released for free, not a cut chapter like many people seem to believe. Was made available on the Steam version of the game via the Anniversary Update.

Return to the Black Mesa Research Facility as one of the military specialists assigned to eliminate Gordon Freeman. Experience an entirely new episode of single player action. Meet fierce alien opponents, and experiment with new weaponry. Named 'Game of the Year' by the Academy of Interactive Arts and Sciences.

Made by Gearbox Software and originally released in 2001 as an add-on to Half-Life, Blue Shift is a return to the Black Mesa Research Facility in which you play as Barney Calhoun, the security guard sidekick who helped Gordon out of so many sticky situations.

The third and final expansion pack for the original game, and the only one to NOT be available (officially) on Steam. It is exclusive to the PS2 version of the game and plays as a co-op game, similarly to Portal 2 co-op.

Reawakened from stasis in the occupied metropolis of City 17, Gordon Freeman is joined by Alyx Vance as he leads a desperate human resistance. Experience the landmark first-person shooter packed with immersive world-building, boundary-pushing physics, and exhilarating combat.

A short chapter that was cut from the game and released as a standalone experience. Was merged along with the episodes into the base game on Steam since the Anniversary Update.

The first of two episodic expansions. Nowadays available directly through the base game on Steam.

The second of two episodic expansions. Nowadays available directly through the base game on Steam.

Half-Life: Alyx is Valve’s VR return to the Half-Life series. It’s the story of an impossible fight against a vicious alien race known as the Combine, set between the events of Half-Life and Half-Life 2. Playing as Alyx Vance, you are humanity’s only chance for survival.