From Blizzard Entertainment:
Welcome to The Hive Mind
You are Sarah Kerrigan, former Queen of Blades. Once the most feared entity in the galaxy, you now wait in a cell in the depths of a high-security research laboratory. Before the murderous forces of the Terran Dominion close in, you must plot your escape to the dark reaches of space... and reclaim your living empire at the Heart of the Swarm.
Deploy devastating new units across an ever-shifting battlefield. Incinerate advancing foes with the Hellbat, seize air superiority with the Tempest, engulf entrenched enemies with the Swarm Host, and much more.
Lead Sarah Kerrigan as she embarks on a path of furious vengeance. Evolve your brood for maximum devastation, unlock latent psionic powers, and swarm from planet to planet aboard your moon-sized zerg Leviathan.
Experience the next evolution of StarCraft II's global community on Battle.net. Join co-op games with friends, player near-limitless mods in the Arcade, and marshal your forces across ranked and unranked brackets for every level of play.