Although Kerrigan is still a Zerg/Human hybrid, she has lost much of her former powers including the ability to control all Zerg everywhere with a thought. Kerrigan is a former Terran Ghost, mutated and infested into a powerful Zerg/Human hybrid, who is fighting to maintain and expand her control over the recently divided Zerg Swarm after being stripped of her powers at the end of Wings of Liberty, when she was purified through the use of a Xel'Naga artifact. The Heart of the Swarm campaign centers around Sarah Kerrigan, the self-styled 'Queen of Blades'. As players level up Kerrigan through missions, new skills can be unlocked and old skills augmented. With Heart of the Swarm being the second installment in the trilogy, it is believed development was not started until the completion of Wings of Liberty. Whether this is true or not remains to be seen.

Blizzard responded by clarifying the decision to split the campaign into three separate products was to ensure a more complete and epic story, with each of the campaigns being roughly equal in length to the total length of the three campaigns in the original StarCraft. Some fans accused Blizzard of splitting up the three campaigns into different product releases so they could charge more money for each than for a single amalgamated product. The StarCraft II 'trilogy' was announced at Blizzcon 2008 and was met with a mostly positive response, but negative reactions on appeared on Internet forums. Swarm chronologically comes after StarCraft II: Wings of Liberty, the Terran chapter, and before StarCraft II: Legacy of the Void, the Protoss chapter. Heart of the Swarm focuses on the bestial, vicious Zerg collective, known as the Swarm.

StarCraft II: Heart of the Swarm is the second chapter in the StarCraft II trilogy.

Heart of the swarm new units