Halo 3 is a first-person shooter video game developed by Bungie exclusively for the Xbox 360. The game is the third title in the Halo series and concludes the story arc that began in Halo: Combat Evolved and continued in Halo 2.

Halo 3's...

Halo 3 is a first-person shooter video game developed by Bungie exclusively for the Xbox 360. The game is the third title in the Halo series and concludes the story arc that began in Halo: Combat Evolved and continued in Halo 2.

Halo 3's story centers on the interstellar war between 26th century humanity, led by the United Nations Space Command, and a collection of alien races known as the Covenant. The player assumes the role of the Master Chief, a cybernetically enhanced supersoldier, as he wages war in defense of humanity, assisted by human Marines as well as an allied alien race called Elites, which is led by the Arbiter. The game features vehicles, weapons, and gameplay not present in previous titles of the series,[9] as well as the addition of saved gameplay films, file sharing, and the Forge map editor; a utility which allows the player to perform modifications to multiplayer levels.

source: http://en.wikipedia.org/wiki/Halo_3