StarCraft 2: Heart of the Swarm sells 1.1 million copies in two days

The first expansion for StarCraft 2, Heart of the Swarm, sold approximately 1.1 million copies worldwide in its first two days on sale, developer Blizzard Entertainment said in a release today.

Blizzard said Heart of the Swarm's initial sales figure accounts for both retail and digital sales through Battle.net, but did not provide a breakdown of physical versus download sales. By comparison, Blizzard announced in August 2010 that StarCraft 2: Wings of Liberty had sold more than 1 million copies in its first day on sale, going on to sell more than1.5 million copies in the first 48 hours of availability.

Blizzard also boasted that 1.1 million viewers tuned into the company's day-long broadcast of launch events and community celebrations, with a peak concurrent viewership surpassing 125,000, according to streaming service Twitch.

StarCraft 2: Heart of the Swarm's single-player campaign focuses on the alien Zerg race and its leader Sarah "The Queen of Blades" Kerrigan. The game's multiplayer mode added new units for each of the the game's three playable races. The game was released on Windows PC and Mac on March 12.