Halo 2 is a science fiction first-person shooter video game developed by Bungie Studios. Released for the Xbox game console on November 9, 2004, the game is the second title in the Halo series, the sequel to Halo: Combat Evolved and followed by Halo 3. A Windows Vista version of the game was released on May 17, 2007. It was developed by a team at Microsoft Game Studios who are referred to internally as "Hired Gun". Game developer Pi Studios produced editing tools for this version, which allows users to create multiplayer maps.

The game features a new game engine, as well as using the Havok physics engine; added weapons and vehicles; new multi-player maps; and a continuation of the storyline from Halo: Combat Evolved. In the game, humans, who have developed faster-than-light travel and colonized hundreds of worlds, have been engaged in a war against a collective of Xenocidal alien races, the Covenant. The player assumes the roles of Master Chief and the Arbiter, and fights enemies on foot or with a collection of alien and human vehicles.

After its initial release, Halo 2 was the most popular video game on Xbox Live, holding that rank until the release of Gears of War for the Xbox 360 nearly two years later. By June 20, 2006, more than 500 million games of Halo 2 had been played and more than 710 million hours have been spent playing it on Xbox Live; by May 9, 2007, this number had risen to more than five million unique players on Xbox Live As of May 9, 2006, Halo 2 is the best-selling first-generation Xbox game with 8 million copies sold worldwide, and 6.3 million copies sold in the US alone. Critical reception of the game was generally positive, with most publications lauding the strong multiplayer component; at the same time, the campaign was the focus of criticism for its cliffhanger ending. On February 9, 2006, Nick Baron announced that a version of Halo 2 would be released on PC, but exclusively for the Windows Vista operating system (though this limitation can be removed by a patch). The game was ported by a small team at Microsoft Game Studios (codenamed Hired Gun) who worked closely with Bungie Studios.

Gameplay

Halo 2 is a story-driven action-shooter game with a first-person perspective. The game features an expanded range of vehicles, as well as other gameplay changes compared to its predecessor. In the original Halo, health and shield bars are visible on-screen. In Halo 2, the health bar is no longer visible; instead, shield regenerates quickly when the player is not taking damage.