The Zerg: StarCraft's Swarm, Hive Mind and Infestation Explained

StarCraft (1998) gave its bugs a theology. Blizzard's game shipped with three species and a manual that told their history: the Xel'Naga, an ancient race that seeded the galaxy with life, had tried twice to create a successor, first the Protoss, whose purity of form they perfected, then the Zerg, whose purity of essence they would perfect by binding a whole species into a single will. The Zerg they found on Zerus were larvae that lived by burrowing into larger animals and taking on their strengths; the Xel'Naga gave them the Overmind, a vast brain that thought for every Zerg at once, and the Overmind turned on its makers and consumed their fleet. The Swarm then spread across the sector, planet by planet, adding every useful species to itself, and reached the human worlds of the Koprulu sector in time for the game.

StarCraft II (2010–2015) rewrote the creator. The Overmind, it turned out, had been the tool of Amon, a fallen Xel'Naga who wanted the Zerg as a weapon to end the cycle of creation, and the Overmind's hunger for the Protoss was Amon's design; the Overmind's one free act was to create a Zerg that could defy him. That Zerg was Kerrigan, and the trilogy's story is the Swarm's liberation from its maker, which is not a story most games tell about their insect enemies.

The Zerg build nothing; they grow. A hatchery is a living organ set into the ground that spreads creep, a purple carpet of organic matter on which every other Zerg structure must be grown, and produces larvae, the blank cells from which every Zerg unit morphs: a zergling, small and fast and hatched two at a time; a hydralisk, a spine-throwing serpent; a mutalisk, a flying strain adopted from another world; an ultralisk, a building-sized beast with scythes. Each strain was a species once, assimilated and rewritten by the Swarm, and the Swarm's genetic library is its history. Zerg heal in creep, fly without ships through space in a spore state, and die in numbers the player is meant not to count.

The hive mind is layered. The Overmind, in the first game, thinks for all; beneath it the cerebrates, immortal brains that direct broods; beneath them the overlords, floating sacs that relay command to the units in their range, so that a Zerg out of an overlord's reach goes feral. The structure lets the games explain why the Swarm is unbeatable as a whole and stupid in pieces, and why cutting off the head, which the Protoss do at the end of the first game, produces chaos rather than victory. The Swarm has no individuals and no dead; the biomass is recycled and the strain lives on.

Infestation is what the Zerg do to species that will not fit a larva. A human touched by the Swarm's virus is rebuilt from the inside, keeping the memories and losing the will, and the first game's Terran missions are a war against former colonists; the infested Terrans are suicide bombers, and the game's most quoted line is the infested Kerrigan's greeting to the man who left her to die. Sarah Kerrigan was a Confederate ghost, a psychic assassin, serving the rebel Arcturus Mengsk when he abandoned her to the Zerg on Tarsonis; the Overmind saw a mind worth keeping, cocooned her on Char, and produced the Queen of Blades, a human shape in chitin with wings of bone and the Swarm's command.

She ran the Zerg for two games and half of a third. Brood War (1998) ended with her destroying every rival and standing alone; Wings of Liberty (2010) ended with Jim Raynor, who had loved her, using a Xel'Naga artifact to strip the Zerg from her; Heart of the Swarm (2013) has her, human again, choose to become the Queen of Blades a second time to take the Swarm back from a broodmother and destroy Mengsk. The games let their protagonist be a monster by choice, which is the difference between the Zerg and every other hive in fiction.

The insectoid being with a collective mind is a fixture of the abduction literature, and the Zerg are its game. The Mantis beings that abductees have described since the 1980s, tall, praying-mantis-shaped, calm, apparently senior to the Greys who do the handling, are read by the accounts' researchers as a hive species' overseers, and the reported procedures, in which the small workers act with one purpose and no expression, are the overlord-and-zergling structure seen from the table. The hybrid program narrative is infestation as breeding: a species that takes human material and rebuilds it into something that serves the hive.

The direction of influence is not in doubt here. StarCraft's designers have named their sources as the Tyranids of Warhammer 40,000, the Xenomorph and the bugs of Starship Troopers, none of them the abduction reports, and the Swarm's look and rules were set in a Blizzard office in 1997. What the game and the reports share is a source further back: the ant hill and the beehive, which humans have read as tyranny or as harmony for as long as they have watched them, and which both the Zerg and the Mantis literature read as tyranny. The alien video games article places StarCraft in the history of the medium; the Swarm remains its most complete alien society.