Half-Life

If you were looking for the scientific and mathematical term, bugger off to The Other Wiki.

Half-Life is an award-winning, genre-defining first-person shooter PC game, released in 1998 by Valve Software. The game's success spawned one sequel series and numerous spin-offs.

Plot
Gordon Freeman is a physicist in the isolated Black Mesa Research Facility, New Mexico, who is locked in a scanning chamber after pushing a specimen into the path of the scanning beam. The scanning of this specimen creates a "resonance cascade", opening a portal between the Black Mesa facility and an alien borderworld called Xen. He and a group of surviving scientists discover that this portal has led to a number of aliens portalling into the facilities, and a group of government soldiers are killing off both aliens and scientists in order to cover up the incident. Discovering that the only way to close the rift and hopefully stop the killing is to step through into the Xen world and kill the Nihilanth, a monster holding the rift open, Freeman works to do so.

In the sequel, Half-Life 2, Freeman is awoken from an extended, 10-20 year stasis by the G-Man, a mysterious suited man with odd speech patterns who picked up and "employed" Freeman at the end of the first game. Freeman is transported to City 17, discovering that the world has been taken over by an extradimensional force known as the Combine. Joining the resistance with old friends Barney Calhoun, Dr. Isaac Kleiner, Dr. Eli Vance, and his daughter, Alyx Vance (and her giant robot, D0g), Freeman, a now-messianic figure to the oppressed masses, helps stage an uprising against the Combine and their leader on Earth, Dr. Breen.

Spin-offs
As well as the sequel and the immediate offshoots of the sequel (Half-Life 2 Episodes 1-3), the Half-Life continuum has spawned a number of spin-offs. These include -


 * Half-Life: Opposing Force
 * A spin-off of the original Half-Life, in which you play from the perspective of U.S. Marine Corporal Adrian Shepherd.


 * Half-Life: Blue Shift
 * A spin-off of the original Half-Life, in which you play as Black Mesa security guard Barney Calhoun.


 * Counter-Strike
 * A popular multiplayer game using the Half-Life engine pitting 'terrorists' against 'counter-terrorists.'


 * Team Fortress 2
 * A multiplayer game based off of the Half-Life 2 engine that has become famous for its cel-shaded graphics and innate sense of humour.


 * Portal
 * The seminal video-game spin-off, Portal tells the story of Chell, the mute female protagonist, who wakes up one day in an aesthetically bland cell by a cheery AI voice named GLaD0S. GLaD0S reveals the protagonist is in an Enrichment Centre owned by Aperture Science Laboratories, and is to be the latest test subject to try out the Aperture Science Handheld Portal Device, or Portal Gun, a gun which can shoot portals and pick up and throw solid objects. However, as the game continues, the player (and by extension, the protagonist) begins to realize something is not all right in the facility...
 * Portal has since become a critically-acclaimed game in its own right, lauded for managing to successfully mix the first-person perspective and the puzzle game. It is also praised for the often dark comedy in the game - GLaD0S' increasingly outlandish claims, the promise of "cake", the Weighted Companion Cube, the cheery yet dangerous turrets, and the song that plays over the credits, "Still Alive", have all been singled out for praise, and the promise of "cake", the Weighted Companion Cube and "Still Alive" have all become internet memes.
 * Portal 2 is due to be released in February of 2011. And the fans rejoiced.

Missions in this Continuum

 * Fullife Consequences, Part 1, Part 2, Murtagh and Titus (DF)