Half-Life is a 1998 first-person shooter game developed by Valve Corporation and published by Sierra Studios for Windows. It was Valve's debut product and the first game in the Half-Life series. The player assumes the role of Gordon Freeman, a scientist who must escape from the Black Mesa Research Facility after it is overrun by alien creatures following a disastrous scientific experiment. The gameplay consists of combat, exploration and puzzles.
Half-Life 2 is a 2004 first-person shooter (FPS) game developed and published by Valve Corporation. It was published for Microsoft Windows on Valve's digital distribution service, Steam. Like the original Half-Life (1998), Half-Life 2 is played entirely from a first-person viewpoint, combining shooting, puzzles, and storytelling. It adds features such as vehicular and physics-based gameplay. The player controls Gordon Freeman, who joins a resistance to liberate Earth from the Combine, a multidimensional alien empire.
Half-Life: Alyx is a 2020 virtual reality (VR) first-person shooter game developed and published by Valve. It was released for Windows and Linux, with support for most PC-compatible VR headsets. Set five years before Half-Life 2 (2004), players control Alyx Vance on a mission to seize a superweapon belonging to the alien Combine. Like previous Half-Life games, Alyx incorporates combat, puzzles and exploration. Players use VR to interact with the environment and fight enemies, using "gravity gloves" to snatch objects from a distance, similarly to the gravity gun from Half-Life 2.