Pop quiz, hotshot: are the setting and story of StarCraft part of the military sci-fi, space opera, or sci-fi horror genres? If you answered, “All three!” then congratulations—you really know your science fiction subgenres. There’s a lot going on in the StarCraft universe, and it’s not always easy to keep it all straight. If you’re looking for a refresher—or just a simple way to explain StarCraft’s story to your friends—this blog has you covered.

Part 1: The Distant Past

Eons ago, the xel’naga arrived in our galaxy and kindled life on countless worlds throughout the Milky Way. Their goal: wait for two species to achieve what the xel’naga called “purity of essence” and “purity of form,” and help them ascend into a new form of life which would take the xel’naga’s place, thus restarting the cycle.

The xel’naga called this the Infinite Cycle. Unfortunately, that turned out to be a bit of a misnomer.

Amon, one of the xel’naga, resolved to break the cycle and remake the universe according to his own design. He directly interfered with two species, the protoss and the zerg, imbuing them with purity of form and essence respectively. When the other xel’naga caught on to his plan, Amon unleashed the zerg. The zerg killed most of the xel’naga, but Amon was ultimately defeated and banished. The surviving xel’naga retreated into deep hibernation, leaving the protoss and the zerg to their own devices. For a long time, life in the galaxy continued as it always had . . . until a plucky young species of bipedal, hairless monkeys decided to see what’s out there among the stars.

Part 2: StarCraft

In the year 2259, human colony ships reach the distant Koprulu Sector. The terrans establish colonies, several political factions emerge, and, in true human fashion, everyone goes to war almost immediately. When the colony world Korhal IV rebels against the Terran Confederacy and declares its independence, the Confederacy destroys the planet via nuclear bombardment. This atrocity leads to the rise of the Sons of Korhal, a group of freedom fighters led by Arcturus Mengsk.

Rebel Yell

Not long after, the terrans get their first taste of what dangers lurk in the Koprulu Sector when zerg attack the worlds of Chau Sara and Mar Sara. The zerg attack on Chau Sara is followed by protoss warships sterilizing the entire planet from orbit, burning the zerg infestation out, along with all other life. Mengsk sees an opportunity to get revenge on the Confederacy by luring the zerg to the Confederate homeworld of Tarsonis, and with the help of former Confederate Marshal Jim Raynor and the psionic Ghost operative Sarah Kerrigan, his heinous plan succeeds.

Overmind

Victory comes at a cost, however. Against Jim Raynor's pleas to save her, Arcturus Mengsk abandons Kerrigan in the final battle, leaving her to be captured by the zerg. On the zerg hive planet of Char, the Overmind transforms Kerrigan into the infested Queen of Blades. By assimilating psionic humans, the Overmind believes it can gain the upper hand against its ancient enemy, the protoss. The scheme succeeds when the zerg learn the precise location of the protoss homeworld of Aiur. Eager to assimilate the protoss and combine their purity of form with the zerg’s purity of essence, the Overmind launches a massive invasion, and after a brutal siege, Aiur falls.

The Fall

With Aiur taken by the zerg, the protoss are forced to reconcile a division within their own kind that goes back a thousand years. The protoss Zeratul discovers that the void energies he and his outcast Dark Templar brethren wield can permanently destroy zerg brood leaders. Forging an unlikely alliance with Jim Raynor, the disgraced protoss Executor Tassadar, and Executor Artanis, Zeratul and the Dark Templar join the fight to retake Aiur. During the final assault, Tassadar makes the ultimate sacrifice, channeling void energies into his supercarrier as he rams his ship into the Overmind, utterly destroying the zerg hive mind.

Part 3: Brood War

The Stand

With the Overmind gone, the zerg run rampant. The protoss concede that they cannot retake their homeworld and instead fall back to the home of the Dark Templar, the planet Shakuras. Unfortunately, the zerg infest Shakuras as well; the only hope of cleansing the planet is by reactivating a dormant xel’naga installation. Zeratul and Artanis hunt down two crystals that power the installation, aided by the Queen of Blades, now freed from the Overmind’s control. Despite Kerrigan’s eventual betrayal, the protoss succeed in awakening the installation, cleansing Shakuras.

The Iron Fist

Back on Earth, news of the zerg and protoss spreads like wildfire, kindling fears of alien invasion. The United Earth Directorate (UED) sends an expeditionary fleet under Admiral Gerard DuGalle to bring the rogue colonies under Earth’s control and neutralize the alien menace. The fleet captures psi disrupter technology, and an assault on Korhal catches Mengsk’s Terran Dominion flat-footed. DuGalle leads a successful attack on Char, where the UED subjugates a nascent Overmind and enslaves the zerg Swarm.

The Queen of Blades

Recognizing the UED threat, Kerrigan convinces her erstwhile allies to once again fight alongside her and joins forces with Raynor and Mengsk. Wary of Kerrigan, they fear she will betray them once her brood has regained its strength, which—of course—she does. Emboldened by victory, Kerrigan coerces Zeratul to aid her in slaying the fledgling Overmind under UED control. The Dark Templar kills the Overmind once and for all, and with the psi disrupter destroyed, all zerg now follow Kerrigan. A combined fleet of UED, Dominion, and protoss forces bear down on Kerrigan, but the Queen of Blades prevails.

Part 4: Wings of Liberty

In the aftermath of the Brood War, things are quiet for a while. Mengsk rebuilds his Terran Dominion, the protoss prepare to retake Aiur, and the zerg . . . are oddly not overrunning the entire galaxy. Working as a mercenary, Raynor is tracked down by Zeratul, who tells him of an ancient xel’naga prophecy that foretells a terrible doom for the galaxy, which can only be stopped by Kerrigan. With the assistance of Mengsk’s son Valerian, Raynor hunts down xel’naga artifacts to build the Keystone, a device that de-zergifies Kerrigan, freeing her of the corruption. The plan works, but at a terrible cost.

Part 5: Heart of the Swarm

Valerian sequesters Kerrigan at a secret research facility to study the Keystone’s effects on her. When Dominion forces storm the facility, Kerrigan escapes on her own. Vowing revenge against Mengsk, Kerrigan begins to rebuild her brood when Zeratul tracks her down, informing her of an ancient xel’naga prophecy that predicts Kerrigan being remade as a primal zerg. Kerrigan travels to Zerus and the Primal Queen of Blades is reborn. She learns that an agent of Amon has been pulling the strings behind the scenes all along, setting the final stage of Amon’s plan in motion. Kerrigan ties up her loose ends on Korhal by killing Arcturus Mengsk and leads her zerg swarm away to prepare for the inevitable showdown with Amon.

Part 6: Legacy of the Void

As Artanis prepares for the final assault to retake Aiur, Zeratul pays him a visit and tells him of an ancient xel’naga prophecy warning of Amon’s return. Amon returns and bends the Aiur protoss to his will via the Khala, their shared psionic link. Zeratul and the Dark Templar free some of their brethren, including Artanis, but Zeratul is killed during the fight. Artanis sets out to secure the Keystone device that de-zergified Kerrigan, hoping that it can be used against Amon. Artanis succeeds in bringing some rogue protoss back into the fold, and forges an alliance with Raynor, Valerian, and Kerrigan. They launch a final assault on Aiur, and with the help of the Keystone, Artanis manages to free the protoss, banishing Amon into the void.

Kerrigan rallies her allies to end Amon once and for all. Amon’s forces are making their last stand on the xel’naga temple world of Ulnar, but with the help of the last surviving xel’naga, Kerrigan ascends. Now a xel’naga herself, she uses her new, cosmic powers to lead the combined forces in the ultimate destruction of Amon.