More than a million fans also tune in to Major League Gaming eSports tournament
Real-time strategy title StarCraft 2: Heart of the Swarm has rushed to more than 1.1 million sales in just two days.
The number of copies for the expansion sold includes sales made through both retail and digital channels.
As well as reaching the impressive sales milestone during its opening couple of days, Blizzard also announced that more than 1.1 million viewers tuned in to the developer’s day of launch events and community celebrations, with the number of concurrent viewers peaking at 125,000.
More than 1.1 million viewers also watched the Heart of the Swarm Major League Gaming Winter Championship tournament that took place in Texas last weekend, with peak concurrent viewership hitting 157,000.
“We want to thank the global StarCraft community for the incredible passion and support they've shown for Heart of the Swarm,” said Blizzard CEO Mike Morhaime.
“In addition to a brand-new single-player campaign, we added a ton of enhancements with this expansion to make StarCraft II even more fun to play, and more exciting to watch. We're pleased to see gamers and eSports fans around the world enjoying Heart of the Swarm.”
As well as early commercial success, StartCraft 2: Heart of the Swarm was also received favourably by critics, garnering an average rating of 85 on Metacritic.