Quake II, released on December 9, 1997, is a first-person shooter computer game developed by Id Software and distributed by Activision. It is not a sequel to Quake; it merely uses the name of the former game due to Id's difficulties in acquiring a trademark for alternative titles. The soundtrack for Quake II was mainly provided by Sonic Mayhem, with some additional tracks by Bill Brown. The game was made available on Steam on August 3, 2007.
The next game released with the title Quake III Arena, is not considered to be related to Quake or Quake II as it is multiplayer focused, and has a dissimilar storyline. A direct sequel, titled Quake 4, was released in October 2005 for the PC (Microsoft Windows and GNU/Linux), and later for the Xbox 360 and the Macintosh. A prequel to Quake II, Enemy Territory: Quake Wars, has been produced by Splash Damage.
Quake II takes place in a science fiction environment. In the single-player game, the player assumes the role of a Marine named Bitterman taking part in "Operation Alien Overlord", a desperate attempt to protect Earth from alien invasion by launching a counter-attack on the home planet of the hostile cybernetic Strogg civilization. Most of the other soldiers are captured or killed almost as soon as they enter the planet's atmosphere, so it falls upon Bitterman to penetrate the Strogg capital city alone and ultimately to assassinate the Strogg leader, Makron.