Heart of the Swarm features a new campaign continuing the epic story of Sarah Kerrigan, Queen of Blades, as she gathers the remnants of the zerg Swarm and plots her revenge against the treacherous dictator of the Koprulu sector, Arcturus Mengsk. It also introduces several new multiplayer units and features that enhance the acclaimed StarCraft II online experience.

Heart of the Swarm picks up the story of StarCraft II where Wings of Liberty left off, focusing on Kerrigan's quest to reunite the Swarm and exact revenge on Arcturus Mengsk. Over the course of 20 campaign missions, players will follow Kerrigan as she sweeps across the galaxy, incorporating a variety of distinctive zerg species into her brood. Kerrigan will grow in strength from mission to mission, and players will be able to customize her with powerful new abilities, as well as evolve various zerg strains into fearsome new subspecies to suit their play style.

New weapons of war also debut in Heart of the Swarm'smultiplayer, including new units such as Terran Hellbats, Zerg Swarm Hosts, and Protoss Tempests, while certain existing units from Wings of Liberty will be updated with new capabilities. New features will enhance the game experience, including group and clan systems; unranked matchmaking; Global Play, enabling players to battle others in different regions around the world; additional stat tracking; user interface improvements; an enhanced physics system, for more visceral looking battles; multiplayer replays, to watch replays with friends; a leveling system that gives Heart of the Swarm players a new way to earn customization options for their online profiles; and much more.

As of the end of its first two days of sales, Heart of the Swarm had sold through approximately 1.1 million copies worldwide, including both retail and digital sales.

Last weekend, more than 1.1 million viewers tuned in to see the StarCraft II: Heart of the Swarm tournament at the Major League Gaming (MLG) Winter Championship in Dallas, Texas. Heart of the Swarm reached a peak concurrent viewership of more than 157,000 viewers, as reported by Twitch.

“We want to thank the global StarCraft community for the incredible passion and support they've shown for Heart of the Swarm,” said Mike Morhaime, CEO and cofounder of Blizzard Entertainment. “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.”

“StarCraft II has been a premier game at Major League Gaming events since Wings of Liberty was released ,” said Sundance DiGiovanni, CEO of Major League Gaming. “Heart of the Swarm has generated even more excitement, and we're all looking forward to what the future brings for StarCraft II eSports.”

"StarCraft II has always been one of the most popular games on Twitch, and we've noticed a wave of new viewership since Heart of the Swarm launched last week," said Kevin Lin, COO of Twitch. "Viewer numbers are up just about across the board for the most popular StarCraft II pro-gamers and personalities who stream on Twitch."