StarCraft II: Heart of the Swarm is an expansion pack to the military science fiction real-time strategy game StarCraft II: Wings of Liberty by Blizzard Entertainment. Heart of the Swarm is the second part of the StarCraft II trilogy, with the final part being Legacy of the Void.
The expansion, released on March 12, 2013, includes additional units and multiplayer changes from Wings of Liberty, as well as a continuing campaign focusing on the Zerg race, following Sarah Kerrigan in her effort to regain control of the swarm and exact her revenge on the Terran Dominion’s emperor, Arcturus Mengsk.
On November 4th, during BlizzCon 2017, Blizzard Entertainment announced that StarCraft II would be re-branded as a free-to-play game hence opening the multiplayer to everybody and bringing some changes to previously paid features of the game. The Wings of Liberty campaign was made completely free while the campaigns for Heart of the Swarm and Legacy of the Void still had to be paid for. However, those who had already bought Wings of Liberty before the free-to-play announcement would be gifted the Heart of the Swarm campaign free of charge. This new free-to-play model and changes to the availability of the campaigns was in line with Blizzard’s vision to support the game differently going forward. Micro-transactions such as Skins, Co-op Commanders, Voice Packs and the War Chests proved to be successful and enough to sustain StarCraft II as a story-driven and eSport title.