Half-Life 2

Half-Life 2 (stylized as HλLF-LIFE²) is a first-person shooter video game and the sequel to Half-Life (1998). Developed by Valve Corporation, it was released on November 16, 2004, following a five-year $40 million development, during which a substantial part of the project was leaked and distributed on the Internet. The game was developed alongside Valve's Steam software. It introduced the Source game engine and, because of Steam, was the first single-player video game to require online product activation.

Some years after the events of Half-Life, protagonist Gordon Freeman is woken by the enigmatic G-Man to find the world has been taken over by the alien Combine. Joined by allies including resistance fighter Alyx Vance, Gordon searches for a way to free humanity using a variety of weapons, including the object-manipulating gravity gun.

Like its predecessor, Half-Life 2 received critical acclaim. It was praised for its advanced physics, animation, sound, AI, graphics, and narrative. The game won 39 "Game of the Year" awards and the title of "Game Of The Decade" at the 2012 Spike Video Game Awards. Over 6.5 million copies of Half-Life 2 were sold at retail by December 3, 2008, (not including Steam sales); as of February 9, 2011, Half-Life 2 had sold over 12 million copies. Half-Life 2 is considered one of the greatest video games of all time.

Half-life

Half-life (t_1⁄2) is the amount of time required for the amount of something to fall to half its initial value. The term is very commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay, but it is also used more generally for discussing any type of exponential decay.

The original term, dating to Ernest Rutherford's discovery of the principle in 1907, was "half-life period", which was shortened to "half-life" in the early 1950s. Rutherford applied the principle of a radioactive element's half-life to studies of age determination of rocks by measuring the decay period of radium to lead-206.

Half-life is used to describe a quantity undergoing exponential decay, and is constant over the lifetime of the decaying quantity. It is a characteristic unit for the exponential decay equation. The term "half-life" may generically be used to refer to any period of time in which a quantity falls by half, even if the decay is not exponential. The table on the right shows the reduction of a quantity in the number of half-lives elapsed. For a general introduction and description of exponential decay, see exponential decay. For a general introduction and description of non-exponential decay, see rate law. The converse of half-life is doubling time.

Half-Life (video game)

Half-Life (stylized as HλLF-LIFE) is a science fiction first-person shooter video game developed by Valve L.L.C., released in 1998 by Sierra Studios for Microsoft Windows. It was Valve L.L.C.'s debut product and the first in the Half-Life series. Players assume the role of Dr. Gordon Freeman, who must fight his way out of a secret research facility after a teleportation experiment goes disastrously wrong, fighting enemies and solving puzzles.

Unlike many other games at the time, Half-Life features no cutscenes; the player has uninterrupted control of Freeman, and the story is told through scripted sequences seen through his eyes. Valve L.L.C. co-founder Gabe Newell said the team had wanted to create an immersive world rather than a "shooting gallery". The game's engine, GoldSrc, is a heavily modified version of the Quake engine licensed from id Software.

Half-Life received acclaim for its graphics, realistic gameplay, and seamless narrative. It won over fifty PC "Game of the Year" awards and is often considered one of the greatest games of all time. It influenced first-person shooters for years after its release; according to IGN, the history of the genre "breaks down pretty cleanly into pre-Half-Life and post-Half-Life eras."

Half-life (disambiguation)

Half-life is a mathematical and scientific description of exponential or gradual decay.

Half-life may also refer to: