StarCraft II: Wings of Liberty is a military science fiction real-time strategy video game currently under development by Blizzard Entertainment as a sequel to the award-winning 1998 video game StarCraft. The game is being developed for concurrent release on Microsoft Windows and Mac OS X. The release date is based upon the game meeting Blizzard's quality standards;[4][5] however, parent company Activision Blizzard anticipates Wings of Liberty to be released in the first half of 2010.[6] StarCraft II is split into three installments: the base game with the subtitle Wings of Liberty, and two expansion packs, Heart of the Swarm and Legacy of the Void.