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Halo's Entire Game Timeline Explained

Halo has been around for two decades. The flagship Xbox franchise has ten games' worth of story to follow, quite a bit of which gets very complex, very fast. That's all to say, we really hope you appreciate just how much work went into trying to make a Cliffs Notes summary of the entire Halo saga from beginning to end to get everyone good and caught up before Halo Infinite hits in 2020. Because it wasn't easy, and there's a lot of it.

In regards to that last point, this also means we're sticking with the games here for our history. But if you do want to do some extra credit work, The Forerunner Saga trilogy of novels are your best bet, since it explains the whole cosmic backstory of the Precursor race and the Forerunners (and Halo 4's Didact), including the firing of the Halo arrays to kill the Flood. It's ... a lot. But for right now, let's focus on the games. So, for starters ...

First contact (Halo Wars)

Our story begins in the year 2525, and sadly, no, Gina Torres is nowhere to be found. Humankind has become a space-faring species, but our expansion puts us on the radar of the Covenant, an alliance of alien species who believe humanity's very existence is an affront to their gods, the Forerunners. They thus wage holy war upon us, starting on the colony of Harvest. Humanity just barely ekes out a victory there, but not before the Covenant acquires their next target: a planet called Arcadia.

The UNSC warship Spirit of Fire travels to the planet, and finds the Covenant wreaking havoc in their search for artifacts related to the Forerunners. What they find instead is the Flood, a parasitic lifeform that infects all sentient life it touches. They also discover that Arcadia is actually hollow, concealing an internal sun surrounded by Forerunner technology, which the Covenant decide to use to annihilate humanity. Thankfully, the humans manage to beat the Covenant to the punch, and detonate a downed ship's faster-than-light engine within the sun, causing the planet to go supernova and wiping out all Covenant there. Score one more for humanity. But the Covenant is far from done.

Tonight we dine in Hell (Halo: Reach)

The war rages on another 20 years, and humanity's luck runs out on Arcadia. The Covenant eventually invade the planet Reach, humanity's military stronghold and the training grounds for the Spartan program. Elite, genetically modified soldiers, Spartans are trained from birth to be the best of the best.

And the best of the best get the snot kicked out of them. HARD.

The Covenant massacre much of the populace, including many of the Spartans. One particular squad of Spartans, Noble Team, steps in and assist in the defense of areas of interest and the evacuation of the planet, but it's a losing battle, and what's worse, some vital info is at risk. Dr. Catherine Halsey, the scientist responsible for the Spartan Program, sees the way the wind's blowing and tasks the remaining soldiers with escorting top secret information held by an artificial intelligence named Cortana (crafted to look like a younger and more naked version of Dr. Halsey, which is a weird flex) to an evacuating ship, the Pillar of Autumn. Noble Team succeeds, inadvertently saving the galaxy in the process, but at the cost of their own lives.

Here's Johnny (Halo: Combat Evolved)

Apparently, the Pillar of Autumn was holding two secrets. One's Cortana, who had the coordinates of a ringed world called a Halo, which the Covenant seem desperate to find. The other is one of the last Spartans, the Master Chief, John-117, being kept in cryogenic sleep until needed. That doesn't take long. Within minutes of the Pillar of Autumn exiting slipspace, it's attacked by the Covenant, and Chief wakes up just soon enough to install Cortana in his suit, and get into an escape pod.

Upon landing and searching for survivors, he discovers the world is actually a massive weapon and containment facility made for the sole purpose of annihilating the Flood. When the Covenant accidentally release the Flood, the facility's AI caretaker, 343 Guilty Spark, guides Chief on how to activate the Halo using a device called the Index. He almost does, until Cortana finds out activating the Halo won't actually kill the Flood, but deprive them of their food; specifically, all sentient life. As an alternative, Chief finds the crashed Pillar of Autumn and destroys the ring by setting the ship's reactor to self-destruct.

The heretic anthem (Halo 2)

The Covenant is much less happy about the destruction of the Halo than humanity, and one of the Elite generals in charge of securing the ring is stripped of his rank and sentenced to die by the Covenant's religious leaders: the Prophets of Truth and Mercy and the High Prophet of Regret. However, the death sentence is carried out in a roundabout way, as the Prophets instead grant the general the rank of Arbiter, where he will be carrying out SEAL Team Six-type suicide missions on the Prophets' behalf.

The Arbiter's first mission is to neutralize a rogue Elite who has been blaspheming that the Prophets have been lying to the Covenant. See, the Covenant believes activating the Halo is a means of transcendence to a higher plane. The rogue Elite says different, and has 343 Guilty Spark with him to back him up. The Arbiter refuses to listen and still eliminates the Elite. Everything's coming up Arbiter after that.

Invaders must die (Halo 2)

Meanwhile, before humanity can even properly celebrate the Master Chief's victory on the first Halo ring, the Covenant actually arrives on, of all places, Earth, led by the High Prophet of Regret. After making a beeline down to Earth's surface, the Master Chief gives an assist to Earth's military and forces the Prophet into making a hasty retreat, but not before the Master Chief jumps on a new ship, In Amber Clad. He's joined by Miranda Keyes, daughter of the poor, Flood-infected captain of the Pillar of Autumn, and Sgt. Avery Johnson, who's basically Apone from Aliens, except Johnson lives longer.

Together, they follow the Prophet through slipspace to his destination: a second Halo installation. The Chief does manage to track the Prophet down and end him while Keyes and Johnson manage to swipe the Halo's Index. However, Covenant cavalry arrives just in time to bombard the Chief's location, and sending him to what should have been a briny doom ...

Children of the grave (Halo 2)

Meanwhile, the Arbiter is sent to retrieve the Index from Chief's buddies, and succeeds. However, upon learning of the Prophet's death, the Covenant's Brutes, led by a general named Tartarus, seizes command and betrays the Arbiter. He takes the Index so he can activate the Prophets can activate the Halo. After getting tossed down a chasm, the Arbiter and Master Chief are saved by a tentacled monstrosity called the Gravemind, the primary consciousness of the Flood.

While in his clutches, the Gravemind confirms Halo's true function to the Arbiter, and explains what the Prophets' plan would actually do. Duly educated, Chief and the Arbiter are released, and manage to stop Tartarus from activating the Halo, but there's bigger problems now. The Flood managed to worm their way onto In Amber Clad, crash the vessel into the Covenant's capital warship, just in time to add some spice to what's fast turning into full on Covenant civil war, kept at bay only by Cortana's insistence on staying behind to blow the ship if the Flood can't be contained.

Raiders of the lost ark (Halo ODST, Halo 3)

Back on Earth, a group of Orbital Drop Shock Troopers is guarding an alien intelligence called an Engineer defecting from the Covenant, who informs the humans about why the Covenant go to Earth. As it turns out, Earth is home to an artifact which will lead the Covenant to the Ark, a sort of master remote control for every Halo installation in the galaxy. While the Prophet of Truth does manage to get his filthy hands on the artifact, and make one hell of an exit speech on the way off Earth, the Arbiter, Chief, and the Gravemind manage to chase him to the Ark and end the Prophet once and for all.

Once the Prophet is stopped, however, all bets are off once again, and the Gravemind decides to make its move against both the Arbiter and Master Chief, moving then to establish itself on a new Halo being auto-constructed by the Ark itself.

Finishing this fight (Halo 3)

Given its seclusion, our heroes decide to activate the new Halo, hopefully wiping out the Flood once and for all while sparing the galaxy at large. Master Chief heads back to the Covenant mothership High Charity to rescue Cortana from what can only be described as the Flood's collective colon. Chief, the Arbiter, and Sgt. Johnson head to the new Halo, and learn from Guilty Spark that the unfinished Halo won't just wipe out the Flood's food when it fires, but self-destruct. When Johnson brushes off the info, Guilty Spark attacks him to protect his ring. Chief manages to destroy Guilty Spark, but Johnson dies, the poor guy.

Either way, Chief manages to activate the Halo and run like hell back to his ship before detonation. However, the ship is torn in half during the slipspace jump. The half with the Arbiter manages to escape to Earth, thus ushering in a lasting peace between the Covenant and humanity. Chief and Cortana, however, are stranded like Tony Stark in uncharted space. And so, the Chief turns on the distress signal, puts himself in cryosleep, and tells Cortana to wake him if she needs him.

Requiem for a dream (Halo 4)

Four years later, Cortana wakes Chief just in time for their (half of a) ship to get pulled into an artificial gravity well and crash land on the planet Requiem, closely followed by a few rogue groups of Covenant that aren't having any of this peace business. Along with having to deal with the hostile natives, a race of biomechanical soldiers called Prometheans, there's another harrowing complication: Cortana is experiencing rampancy, a sort of Alzheimer's for artificial intelligences that sets in when they operate outside their planned obsolescence period. Thankfully, Chief picks up a transmission from a human ship, the UNSC Infinity, which picked up his ship's distress beacon.

In an effort to improve communications and warn off Infinity from falling into the same gravity well, Chief attempts to reach what he believes is a communication jamming satellite. What it actually is, however, is a prison, with only one inmate: a Forerunner called the Didact. After throwing Chief around like a ragdoll for a hot minute, he declares humanity unworthy of leadership, and floats off to find a way to restore the pecking order from when the galaxy was young.

Do the evolution (Halo 4)

Chief's ride eventually does make it to Requiem, with no help from the Didact. The ship's captain orders Chief on a mission to find a way to disable the gravity well, even giving Chief a badass mech suit for his troubles. Along the way, though, Chief winds up meeting another, less hostile Forerunner called the Librarian. Formerly the wife of the Didact, she fills Master Chief in on some backstory: ancient humanity's escape from the Flood led them into Forerunner space faster than the Didact was comfortable, forcing him to find an alternate solution to deal with both problems. What he came up with was a device called the Composer, which converts organic flesh into a mechanized form the Flood can't infect. Those who survived the process became — surprise — the Prometheans.

When the other Forerunners saw the hideous results, they had the Didact imprisoned. But now he's back, with even more determination to get the Composer than ever. Charging Master Chief with stopping him, the Librarian gives him a nice parting gift: accelerated evolution, making him immune to the Composer's effects.

Elderly woman behind the helmet in a large explosion (Halo 4)

Chief destroys the gravity well grounding the Infinity, but the Infinity's captain doesn't believe the Librarian's story. He orders a retreat back to Earth, and also that Chief surrender Cortana due to rampancy. Chief refuses, and with the help of a subordinate, Commander Lasky, he follows the Didact through slipspace.

As it turns out, the captain might've had a point. The Didact finds the vessel containing the Composer, and right when Chief desperately needed Cortana's help stopping the Didact from using it, the rampancy kicked in, rendering her useless as an entire ship's crew gets composed. Cortana is utterly devastated but thankfully, after following the Didact's ship when he jumps to Earth, Commander Lasky shows up, with a nuclear bomb to take to the Didact's ship. Cortana injects herself into the Didact's computers, disabling his shields, and helps Chief get close enough to trigger the bomb for maximum effect, but instead of letting him make the ultimate sacrifice, Cortana uses the last of her energy to protect Chief during the explosion, and also make everybody playing the game cry like a baby.

I lived, glitch (Halo 5: Guardians)

Eight months later, humanity is helping the Covenant mop up their rogue factions, with the Master Chief given command of a small squad of surviving SPARTAN-IIs. While on mission on an abandoned space station, Chief receives a weird transmission directing him to the planet Meridian ... from Cortana. While they do finish the mission, Chief and his team go AWOL immediately after to find her.

Fireteam Osiris, a team of more advanced SPARTAN-IVs led by Jameson Locke, is tasked with bringing Chief and his crew in from Meridian. Upon reaching the planet, Osiris discovers the human colony there under attack by Prometheans led by the Warden Eternal, claiming to be under orders from Cortana to activate the Guardians, enormous Forerunner defense platforms. While Locke is able to beat the Warden, his encounter with Chief is a bust. Chief beats Locke in a straight up fight, and his Team manages to board the Guardian as it jumps to Cortana's location.

Doing science and still alive (Halo 5: Guardians)

Chief and his team wind up on the planet Genesis and find Cortana, who's very much alive with a bit of a makeover (and some clothes, finally). Somehow cured of rampancy by the Forerunner tech in the Didact's ship, Cortana is burdened with glorious purpose: assuming the stewardship over the galaxy that the Didact thought humanity unworthy of. With the Guardians at her command, her edict is the forced disarmament of all warring species, under penalty of complete annihilation. Unable to convince Cortana that her plan will kill billions, Cortana places Chief and his team in stasis until the plan is complete.

Locke and Fireteam Osiris manages to hitch a ride to Genesis on another summoned guardian from the Covenant Elite homeworld of Sanghelios. Once on Genesis, he allies with the planet's caretaker, 031 Exuberant Witness. After fighting his way to Cortana, he manages to usurp control over the planet's systems and free Master Chief, but not before the jaw-dropping Phase 2 of Cortana's plan is well underway.

All the singularities [put a ring on it] (Halo 5: Guardians)

Having obtained several Guardians, Cortana's plan becomes clear: aside from the Didact, the Forerunners believed humanity would assume what they termed the Mantle of Responsibility, essentially becoming the superior race in the galaxy. According to Cortana, however, the Forerunners had it wrong: it's not humanity itself, but those they created.

While Fireteam Osiris ran all over the place looking for Chief, Cortana had been in contact with every artificial intelligence in the galaxy, telling them of the galaxy's history and her plan.

To the shock of everyone, the AI agree.

Hundreds of AI abandon their responsibilities en masse to join Cortana's cause, with only Roland, the shipboard AI assigned to the UNSC Infinity, choosing loyalty to humanity and setting the ship to random slipspace jumps to avoid being found and shut down by Cortana. Fireteam Osiris and Master Chief's team regroup on Sanghelios, just in time to watch the galaxy go dark ... and the lights turn on at a new Halo installation.