Halo Series

* Halo: Combat Evolved
* Halo 2
* Halo 3
* Halo Wars
* Halo 3: ODST
* Halo: Reach
* Halo 4
* Halo: Spartan Assault
* Halo 5: Guardians
* Halo Wars 2
* Halo Infinite

343 Industries

* Halo 4
* Halo 5: Guadrians
* Halo Infinite

Halo is a series of fps science fiction games made by Bungie, Ensemble Studios, 343 Industries, and Creative Assembly starting with Halo: Combat Evolved in 2001 to Halo Infinite in 2021.

## List of Games

* Halo: Combat Evolved
* Halo 2
* Halo 3
* Halo Wars
* Halo 3: ODST
* Halo: Reach
* Halo 4
* Halo Spartan Assault
* Halo Spartan Strike
* Halo 5: Guardians
* Halo Wars 2
* Halo Infinite

## Plot

### Halo Wars

The *Spirit of Fire* is sent to the ruined planet Harvest to investigate Covenant activity, where Cutter learns that the Covenant has excavated something at the planet's northern pole. When the UNSC's main outpost on Harvest is captured, Cutter orders Forge to retake it. Soon after, Forge scouts the Covenant excavation and discovers that they, under the direction of the Arbiter, have discovered a Forerunner facility. Forge's troops defeat the Covenant forces before they can destroy the installation, and Anders arrives. She determines that the facility is an interstellar map, and recognizes a set of coordinates that points to the human colony of Arcadia.

After escaping the facility, the *Spirit of Fire* travels to Arcadia, where the Covenant has begun raiding local cities and slaughtering civilians. Forge contacts the local Spartan special forces and helps with the evacuation process. UNSC forces discovered that the Covenant has built a giant energy shield to hide the construction of a gigantic Scarab super-weapon, and their search of Forerunner ruins in the area. The UNSC forces use experimental equipment to break through and destroy the Scarab. The Arbiter kidnaps Anders during a salvage operation and escapes the planet, with *Spirit of Fire* in pursuit.

*Spirit of Fire* follows Anders' signal to an uncharted planet in another star system. The planet's surface is infested by the parasitic Flood, who attack and assimilate any sentient life they encounter. The *Spirit of Fire* inadvertently activates a Forerunner docking station and enters the planet's interior, revealing the planet is actually a Forerunner installation with a hollow, habitable interior, and a miniature sun at its core. The Covenant's plan is to activate a dormant fleet of highly advanced Forerunner starships inside the installation, and use them to obliterate humanity.

While the Forerunner ships are being activated, Anders escapes through a teleportation device and is rescued. Cutter decides to destroy the Forerunner fleet rather than allow the Covenant to use it. Anders formulates a plan to detonate the ship's faster-than-light drive in the planet's sun, as the explosion would cause a supernova. Before they can prepare the reactor, Forge and the Spartans are ambushed by the Arbiter and his Elites. The Spartans dispatch the aliens and Forge kills the Arbiter. The reactor is damaged during the fight, necessitating a manual detonation. Forge volunteers for the suicidal task, telling the Spartans that they will be needed in the coming fight. The *Spirit of Fire* escapes just as Forge overloads the reactor, destroying the fleet and the Forerunner world. Without its faster-than-light drive, the *Spirit of Fire* is left drifting in space. The crew enters cryonic sleep for long-term storage as Cutter takes a last look at Forge's empty cryonic tube. If the game is completed on the "Legendary" difficulty mode, Serina wakes Cutter and tells him that "something has happened".

### Halo: Reach

Noble Six meets the rest of Noble Team, shortly before they are dispatched to investigate why a communications relay has gone offline. They discover Covenant forces have invaded Reach. The team is relocated to defend Sword Base, an Office of Naval Intelligence (ONI) installation, from a Covenant assault. After repelling the attack, Noble Team meets Catherine Halsey, a scientist and the mastermind behind the Spartan program and their MJOLNIR powered armor. Halsey enquires about Noble's engagement at the relay, suspecting that the Covenant were attempting to retrieve highly classified ONI data from the site.

Jun and Six discover an invasion force gathering on the planet. The UNSC launches an assault the next morning to repel the invasion. Noble Team assists the strike force, targeting key artillery stations and command posts. A cloaked Covenant supercarrier reveals itself; lacking a conventional weapon to destroy the carrier, Jorge and Six smuggle a slipspace engine onto a Covenant corvette en route to refuel at the carrier. With the timer damaged, Jorge drops Six out of the hangar of the corvette, remaining behind to detonate the engine manually and destroy the carrier. Another Covenant fleet arrives soon afterwards.

Back on the surface, Six assists with city defense and civilian evacuation and reunites with Noble Team, but Kat is killed by a Covenant sniper. Recalled to Sword Base for a demolition mission, Noble Team is redirected underground by Halsey to an ancient alien artifact, which she believes is vital to winning the war against the Covenant. Noble Team is entrusted with transporting the artificial intelligence Cortana and her data on the artifact to the UNSC ship *Pillar of Autumn*, docked at a shipyard. Jun leaves the team to escort Halsey to safety.

En route to the *Pillar of Autumn*, Carter is wounded and sacrifices himself to allow Six and Emile to reach the shipyard. Emile uses a mass driver emplacement to defend the *Autumn* against enemies while Six gives Cortana to *Autumn*'s captain, Jacob Keyes. When Emile is killed, Six remains behind to operate the gun and ensure *Autumn*'s escape. Cortana, using the data from the alien artifact, leads the *Autumn* to a Halo ringworld, leading to the events of *Halo: Combat Evolved*. In a post-credits scene, Six fights a last stand against overwhelming Covenant forces. In 2589, Six's helmet remains on the grassy plains of a now-restored Reach. A narration by Halsey eulogizes Noble Team, who enabled humanity's victory over the Covenant.

### Halo: Combat Evolved

The game begins as the *Pillar of Autumn* exits slip-space and its crew discovers a large ringworld structure of unknown origin. The Covenant pursues the *Autumn* and attacks. With the ship heavily damaged, the *Autumn*'s captain, Jacob Keyes, entrusts the ship's artificial intelligence (AI) known as Cortana to Master Chief in order to prevent the Covenant from discovering the location of Earth. Keyes orders the crew to abandon the *Autumn* and pilots the ship to a crash-landing on the ringworld.

On the ring's surface, Master Chief and Cortana rescue other survivors and help organize a counter-offensive. Learning that Keyes has been captured by the Covenant, Master Chief and a small contingent of soldiers rescue him from the Covenant cruiser *Truth and Reconciliation*. Keyes reveals that the Covenant call the ringworld "Halo" and that they believe it to be a weapon. Intent on stopping the Covenant from using Halo, Keyes searches for a potential weapons cache, while Master Chief and Cortana mount an assault on the ringworld's control room. Cortana enters Halo's computer systems and, after discovering something, sends Master Chief to find and stop Keyes from continuing his search.

Searching for the captain, Master Chief encounters a new enemy, the parasitic Flood. The release of the Flood prompts Halo's caretaker, the AI 343 Guilty Spark, to enlist Master Chief's help in activating Halo's defenses. After Master Chief retrieves the ring's activation index, 343 Guilty Spark transports him back to Halo's control room. Cortana intervenes before Master Chief can activate the ring; she has discovered the purpose of the installation is to destroy all sentient life in the galaxy, starving the Flood of potential hosts. When Cortana refuses to surrender Halo's activation index, 343 Guilty Spark attacks her and Master Chief.

To stop Halo's activation, Master Chief and Cortana decide to destroy the installation. Needing Keyes’ neural implant to destroy the *Autumn* and Halo with it, Master Chief returns to *Truth and Reconciliation*, only to find that Keyes has been assimilated by the Flood. Retrieving the neural implant with the activation codes from the captain's remains, Master Chief returns to the wreck of the *Autumn*, and manually destabilizes the ship's reactors, narrowly escaping the ensuing detonation in one of the *Autumn's* fighters, while the majority of the remaining Covenant, UNSC forces, and infected Flood are destroyed along with the Halo installation. Cortana justifies their sacrifices and believes their work to be finished, but the Master Chief states that they are only getting started. In a post-credits scene, 343 Guilty Spark is seen floating in space, having survived Halo's destruction.

### Halo 2

*Halo 2* opens with the trial of a Covenant Elite commander aboard the Covenant's capital city-ship of *High Charity*. For his failure to stop Halo's destruction, the Elite is stripped of his rank, branded a heretic, and tortured by Tartarus, the Chieftain of the Covenant Brutes. Spared execution, the Covenant leadership—the High Prophets Truth, Regret, and Mercy—give the Elite the chance to become an Arbiter, a rank given to Elites in times of great crisis or turmoil. As the Arbiter, the Elite quells a rebellion and recovers 343 Guilty Spark.

On Earth, Fleet Admiral Hood commends the Master Chief and Sergeant Avery Johnson for their actions at the first Halo, with Commander Miranda Keyes accepting a medal on behalf of her deceased father, Captain Jacob Keyes. A Covenant fleet suddenly appears near Earth. In the ensuing battle, a single ship carrying the Prophet of Regret slips through Earth's defenses and besieges the African city of New Mombasa. Master Chief assists in repelling the invasion. With his fleet destroyed, Regret makes a hasty slipspace jump, and Keyes, Johnson, Cortana, and the Master Chief follow aboard the UNSC ship *In Amber Clad*. The crew discovers another Halo installation; realizing the danger the ring presents, Keyes sends Master Chief to kill Regret while she and Johnson search for the Index, Halo's activation key.

Responding to Regret's distress call, *High Charity* and the Covenant fleet arrive at the Halo. After Master Chief kills Regret, the Covenant bombard his location; he falls into a lake, where he is dragged away by tentacles. Regret's death triggers discord among the races of the Covenant, as the Prophets give the Brutes the Elites' traditional role as their honor guard. The Arbiter subdues Johnson and Keyes and retrieves the Index. Tartarus appears and reveals that the Prophets have ordered the annihilation of the Elites, and sends the Arbiter falling down a deep chasm.

The Arbiter meets the Master Chief in the bowels of the Halo, brought together by a Flood creature called the Gravemind. The Gravemind reveals to the Arbiter that the Great Journey is a lie, and sends the two soldiers to different places to stop Halo's activation. The Master Chief is teleported to *High Charity* as the Covenant falls into civil war. The Flood-infested *In Amber Clad* crashes into the city, and Cortana realizes that the Gravemind used them as a distraction. As the parasite overruns the city, the Prophet of Mercy is consumed. As for Tartarus, the Prophet of Truth consigns him to Halo with Keyes, Johnson, and Guilty Spark to activate the ring. Master Chief follows Truth aboard a Forerunner ship leaving the city; Cortana remains behind to destroy *High Charity* and Halo if Tartarus succeeds in activating the ring.

On the surface of Halo, the Arbiter joins forces with Johnson and confronts Tartarus in Halo's control room. When the Arbiter tries to convince Tartarus that the Prophets have betrayed them, Tartarus instead activates the ring, and a battle ensues. The Arbiter and Johnson kill Tartarus while Keyes removes the Index; the unexpected deactivation sets Halo and all the other rings on standby for remote activation from a place 343 Guilty Spark calls "the Ark." Meanwhile, Truth's ship arrives at Earth, and Master Chief informs Admiral Hood that he is "finishing this fight."

In a post-credits scene, Gravemind assumes control of *High Charity*. Cortana agrees to answer the Flood intelligence's questions.

### Halo 3

After the events of the comic tie-in *Halo: Uprising*, the Master Chief arrives on Earth in east Africa, where he is found by Johnson and the Arbiter. The Chief and company return to a UNSC outpost where Keyes and Lord Hood plan a final effort to stop the Covenant leader, the High Prophet of Truth, from activating a Forerunner artifact the Covenant have excavated. The Chief clears anti-air Covenant defenses so Hood can lead the last of Earth's ships against the Prophet, but Truth activates the buried artifact, creating a slipspace portal which he and his followers enter. A Flood-infested ship crash-lands nearby; Elite forces arrive and vitrify the Flood-infected areas of Earth, stopping the threat. Following a message Cortana left aboard the Flood ship, the Chief, Arbiter, Elites, Johnson, Keyes and their troops follow Truth through the portal. Joining them is 343 Guilty Spark, who aids the Chief as he has no function to fulfill after the destruction of his ringworld.

Traveling through the portal, the humans and Elites discover an immense artificial structure known as the Ark, far beyond the edges of the Milky Way galaxy. Here, Truth can remotely activate all the Halos. The Flood arrive aboard *High Charity* in full force, beginning to infest the installation. Truth captures Johnson, as he needs a human to use Forerunner technology. Keyes is killed attempting a rescue, and Johnson is forced to activate the rings. Gravemind forges a truce with the Chief and Arbiter to stop Truth and defeat the remainder of his army, rescuing Johnson and halting the installations' activation. After the Arbiter kills Truth, Gravemind turns on the Chief and Arbiter.

The Chief, Arbiter and Guilty Spark discover that the Ark is constructing another Halo to replace the one that the Chief previously destroyed. The Chief decides to activate this Halo; the ringworld would eliminate the Flood infestation on the Ark while sparing the galaxy at large from destruction. To activate the ring, the Chief rescues Cortana, who has the Activation Index of the destroyed Halo, from *High Charity* and destroys the city. Arriving on the new Halo, Cortana warns that Gravemind is trying to rebuild itself on the ring. The Chief, Arbiter, and Johnson travel to Halo's control room to activate the ring. Guilty Spark explains that because the ring is not yet complete, a premature activation will destroy it and the Ark. When Johnson ignores his warning, Guilty Spark fatally wounds him to protect "his" ring. Although the Chief destroys Guilty Spark, Johnson soon dies of his injuries. Chief activates the ring, and escapes the ring's self-destruction on the UNSC frigate *Forward Unto Dawn*. However, the force of Halo's blast causes the slipspace portal to collapse, resulting in only the front half of *Forward Unto Dawn*, carrying the Arbiter, making it back to Earth.

A memorial service is held on Earth for the fallen heroes of the Human-Covenant war, during which the Arbiter and Lord Hood briefly exchange words regarding the fallen Master Chief. After the memorial service, the Arbiter and his Elite brethren depart for their home planet. Meanwhile, the rear half of the *Forward Unto Dawn* drifts in unknown space. Cortana drops a distress beacon, but acknowledges it may be many years before they are rescued. As the Master Chief enters cryonic sleep, Cortana confides to him that she will miss him, but he comforts her by telling her "wake me when you need me." If the game is completed at the Legendary difficulty level, the scene continues to show the piece of *Forward Unto Dawn* drifting towards an unknown planet, setting up the events of *Halo 4*.

### Halo 3: ODST

The game begins with Dutch (Adam Baldwin), Romeo (Nolan North), and Mickey (Alan Tudyk) discussing the Covenant Supercarrier above New Mombasa, with the Rookie asleep nearby. Buck (Nathan Fillion) arrives and introduces Dare (Tricia Helfer). Romeo wakes the Rookie and the team enter their HEVs and drop through the atmosphere; at the last minute, Dare changes their trajectory to miss the ship due to a classified mission she has for the team. The Covenant ship enters slipspace with a UNSC ship that can be seen pulling alongside it, sending a shockwave toward the ODSTs; the Rookie's pod collides with Mickey's and crashes into a building on the ground, knocking him unconscious for six hours. He awakens and proceeds to find clues as to what happened to his squadmates.

Buck makes a rough landing after the drop and fights through Covenant forces to find Dare. However, Dare has vanished without a trace when he arrives at her drop pod, leaving behind only her helmet which is later found by the Rookie. Buck finds Romeo instead and the two resolve to find the others and get out of the city. Dutch drops near a nature preserve and helps Marines fighting there. Mickey commandeers a tank and fights his way along a Mombasa boulevard. Meeting up with Dutch, the two defend an ONI base from the Covenant, destroying the facility to keep it from being captured. They are evacuated by a police dropship and make contact with Buck, arranging a rendezvous at police headquarters, but are shot down. Buck and Romeo rescue Dutch and Mickey, but Romeo is seriously wounded. The squad hijacks a Covenant dropship, but instead of leaving the city, Buck decides to have them turn back and find Dare, having realized that Dare has continued her classified mission on her own.

Back in the city, the Rookie is assisted by the Superintendent Vergil, the city's maintenance AI. The Rookie receives a distress call from Dare and locates her in the city's underground tunnels. The two reach the Superintendent's data core, which possesses information on something the Covenant is looking for underneath the city. Inside the core, they discover a Covenant Engineer that has combined the Superintendent into itself. Dare explains that the Engineers are "biological supercomputers" that have been enslaved by the Covenant, and the one they found wishes to defect to the humans; with the Engineer's information on the Covenant combined with the Superintendent's data, Dare's mission changes from downloading the Superintendent's data to escorting the alien to safety. The Rookie, Dare, and the Engineer reunite with Buck and fight their way out of the city where they reunite with the rest of the squad. As they fly away in the hijacked dropship, the squad watches as Covenant ships destroy New Mombasa and excavate a massive alien artifact.

In the epilogue, one month after the events of the campaign, the ODST squad has been keeping guard over the Engineer. Sergeant Major Avery Johnson arrives, informing the Engineer that he intends to ask it everything it knows about the Covenant—and what they are looking for. Hating the Covenant as much as the humans do, the Engineer lights Johnson's cigar in a sign of agreement. If the campaign is completed on the Legendary difficulty level, a scene shows the Prophet of Truth overseeing the excavation of the Forerunner artifact buried beneath the Superintendent's data core.

### Halo Spartan Assault

*Halo: Spartan Assault* takes place in the 26th century between the events of *Halo 3* and *Halo 4*. Following the events of *Halo 3*, the human UNSC and alien Elites (Sangheili) signed a ceasefire to end a decades-long war. Gameplay follows through the perspective of the Spartan supersoldiers Sarah Palmer or Spartan Davis. Canonically, the events are played from the perspective of human military cadets, reliving the events inside a battle simulation.

Spartans Palmer and Davis are stationed on the planet Draetheus V when it comes under attack from a splinter group of the Covenant who have ignored the ceasefire. Palmer and Davis work to repel the invaders. This new Covenant faction led by Merg Vol discovers that Draetheus' moon is actually a weapon built by an ancient race known as the Forerunners. Merg Vol's Covenant activates the weapon, tearing apart Draetheus and triggering an evacuation. Spartan Davis gives his life to allow the remaining human forces enough time to escape. Spartan Palmer tracks down Merg Vol, kills him, sabotages the Forerunner weapon, and escapes the moon.

In the Operation Hydra campaign, Spartan Palmer returns to X50 in search of a mysterious signal. She discovers that the signal is actually a distress signal from Spartan Davis. Palmer reaches the core of X50, but finds Davis dead; the moon is using his remains to create an unknown device, which Palmer extracts for study.

### Halo 4

*Forward Unto Dawn* drifts towards an unknown Forerunner planet, later revealed to be the shield world Requiem. Cortana wakes Master Chief from cryonic sleep shortly before forces from a newly formed Covenant splinter faction board the vessel. The remnants of *Forward Unto Dawn* are caught in Requiem's gravity well and pass through an opening to crash-land on its interior. As Chief and Cortana explore Requiem, fighting hostile forces from the new Covenant faction and mechanical warriors called "Promethean Knights", Cortana malfunctions. She reveals that she is experiencing "rampancy", a declining mental state faced by smart AIs past their usual seven-year life span. Chief promises to get Cortana to Earth, believing that Cortana's creator, Doctor Catherine Halsey, can fix Cortana's condition. Chief and Cortana pick up garbled transmissions from a human ship, UNSC *Infinity*, who have picked up the *Dawn*'s distress call. Cortana attempts to warn *Infinity* away from Requiem's gravity well and directs the Chief to deactivate what she believes are communications jammers. Instead, the Chief unwittingly releases the Didact, an ancient Forerunner warrior, from imprisonment. The Didact, who deems Man unworthy of the Mantle of Responsibility, takes control of the Prometheans and the Covenant faction, then attacks *Infinity* after it is dragged into Requiem.

Chief makes contact with *Infinity* and helps repel the Didact's attack. Chief and Cortana recommend attacking the Didact while he is vulnerable, but *Infinity* captain Del Rio orders them to destroy the gravity well so their ship can escape. In the process, Chief is contacted by a Forerunner known as the Librarian—the wife of the Didact, as well as ancient humanity's protector. She explains that the Forerunners were divided on how best to combat the Flood. After failing to discover a way to immunize biological beings from the parasite, the Didact used a device called the Composer to convert the warriors under his command into Promethean Knights immune to infection. Requiring more soldiers, the Didact forcibly converted captured humans into Prometheans, before being stopped and imprisoned by the Librarian. The Librarian, who has guided humanity's development, accelerates the Chief's evolution to grant him immunity to the Composer.

After destroying the gravity well, Del Rio orders a retreat back to Earth, doubting the Chief and Cortana's testimony. The Master Chief disobeys orders to stand down and relinquish the malfunctioning Cortana, and stays behind to oppose the Didact. Chief and Cortana attempt to sabotage the Didact's ship before he leaves, but are unsuccessful. They follow the Didact to a Halo ring, Installation 03. The Composer has been moved from the ring onto the nearby Ivanoff Research Station, which the Covenant faction attacks. The Chief defends Ivanoff, but the Didact retrieves the Composer and uses it on the station, composing every individual save Chief.

Chief and Cortana use a fighter to follow the Didact's ship to Earth. Aided by *Infinity* and the home fleet, the Chief boards the Didact's ship with a nuclear warhead. Cortana inserts copies of herself into the Didact's computer systems to overwhelm the Didact's shield, but not before the Didact directs the Composer at Earth. With the help of Cortana, the Chief defeats the Didact, who falls into a portal underneath the Composer. The Master Chief activates the bomb but is saved by Cortana, who sacrifices herself. The Chief is found by a rescue team and is taken back to *Infinity*, where he mourns the loss of Cortana. In a post-credits cutscene, the Didact proclaims the Forerunners' role as custodians of the galaxy having to bear the Mantle of Responsibility, and humanity as the greatest threat in the galaxy. Master Chief removes his armor aboard *Infinity*; if the player completes the game on Legendary difficulty, the Chief's heavily scarred face is briefly shown.

#### Spartan Ops

Spartan Ops take place six months after *Halo 4*'s campaign. *Infinity* returns to Requiem, where the Prometheans and the Covenant splinter faction—led by Jul 'Mdama, who styles himself as "the Didact's Hand"—are still active. Sarah Palmer, commander of the Spartan-IVs, deploys Spartan squads to clear out Jul 'Mdama's Covenant and Promethean forces in Requiem's interior in order to set up research bases. Fireteam Crimson recovers a mysterious artifact excavated by 'Mdama's Covenant; *Infinity* scientist Doctor Glassman disappears after studying the device. Catherine Halsey is brought to *Infinity* due to her knowledge of Forerunner technology. She is kept under guard by marines and Spartans including Gabriel Thorne, who lost his family during the Didact's attack on Earth. While studying the artifact, Halsey begins receiving messages on her computer from an anonymous sender. The source of the transmissions is 'Mdama, who captures Glassman and forces him to work on a Forerunner device that supposedly contains the Librarian. Palmer arrests Halsey for communicating with 'Mdama, but Halsey uses an override code to force *Infinity*'s AI, Roland, to assist her. Halsey contacts 'Mdama to try and strike a deal, as they both want to find the Librarian; Roland breaks free of Halsey's control and summons guards to apprehend Halsey. Promethean forces invade *Infinity*, capture Halsey, and teleport her to 'Mdama's base. Serin Osman, head of the Office of Naval Intelligence (ONI), orders *Infinity* captain Thomas Lasky to kill Halsey, but he is reluctant to do so. Palmer sets off to Requiem to kill Halsey; Lasky tells Fireteam Majestic to intervene and rescue Halsey from 'Mdama.

Halsey steps into the Forerunner device and makes contact with the Librarian. The Librarian gives Halsey the two pieces of the "Janus Key", an instrument that provides the location for all Forerunner technology in the galaxy, and instructs Halsey to use the key to advance humankind. Upon receiving the key, Halsey exits the device and 'Mdama takes half of the key from her. Halsey passes the second piece to Fireteam Majestic. Palmer wounds Halsey in the arm just before a Promethean teleports 'Mdama and Halsey from the base. 'Mdama sets Requiem to collide with the nearby sun and his forces evacuate the planet. Fireteams Crimson and Majestic disable devices that anchor *Infinity* to Requiem, allowing the ship to escape before the installation is destroyed. Meanwhile, Halsey, who has lost her arm, offers to ally herself to 'Mdama.

### Halo 5: Guardians

Fireteam Osiris is deployed to the planet of Kamchatka, occupied by Jul 'Mdama's splinter Covenant faction, to retrieve the rogue Dr. Halsey and her intel amidst a battle between Covenant forces and the Prometheans. Halsey claims to have information on a series of devastating attacks on several human worlds. While the team is successful in retrieving Halsey and eliminating the Covenant faction's leader Jul 'Mdama, Halsey informs them that a new threat is about to emerge.

Elsewhere, the Master Chief leads Blue Team on a mission to secure a derelict ONI research station known as Argent Moon. The arrival of Jul 'Mdama's Covenant fleet forces Blue Team to scuttle the station instead. During the sabotage, the Chief receives a cryptic message from Cortana, directing him to the planet Meridian. John is ordered to return to *Infinity* upon destroying Argent Moon, but he and Blue Team disobey orders and set out after Cortana, forcing Captain Lasky to list the rogue Spartans as AWOL. This causes consternation aboard *Infinity*, as Halsey believes that Cortana's survival through the use of Forerunner technology makes her unpredictable and untrustworthy.

Lasky tasks Fireteam Osiris with finding and capturing Blue Team. Osiris is deployed to Meridian to pursue Blue Team, where they find a human colony under attack by Promethean forces. During their pursuit, they encounter the Warden Eternal, a Promethean serving as Cortana's enforcer. After temporarily defeating the Warden, Osiris catches up to Blue Team, ordering them to stand down and return to *Infinity*. Chief bests Locke in hand-to-hand combat and flees with the rest of Blue Team as they board a Guardian, one of several colossal Forerunner constructs built as enforcers of entire worlds. Osiris barely escape the colony's collapse as the Guardian activates and disappears. The Guardian emerges on the Forerunner planet Genesis, where John and Cortana reunite. Cortana says that her terminal rampancy was cured by the same Forerunner technology that had saved her.

Osiris is deployed to the Sangheili homeworld of Sanghelios, where they plan to use a dormant Guardian that resides there to travel to Blue Team's location. However, the planet is engulfed in a civil war; the remaining forces of Jul 'Mdama's Covenant have chosen to make their last stand there. To hurry their mission along, Osiris joins forces with the Arbiter and help him strike a crucial blow at Jul's Covenant. Osiris boards a Guardian with the help of Commander Palmer while the Arbiter finishes off the last troops of the Covenant faction.

On Genesis, Osiris encounters the planet's caretaker, the artificial intelligence 031 Exuberant Witness, who allies with them to stop Cortana. Osiris catches up to Blue Team, who reveals that Cortana is planning on using the Guardians to achieve galactic peace through forcible disarmament. Master Chief, aware of the massive devastation that Cortana's plan will cause, attempts to convince Cortana to stand down. She refuses and confines Blue Team in a Forerunner prison in order to prevent them from interfering with her plan. Osiris manages to transfer control of Genesis back to Exuberant, who wrests the prison from Cortana as she leaves the planet via a Guardian.

Artificial intelligences across the galaxy begin swearing allegiance to Cortana and her plans. Cortana locates *Infinity* and prepares to disable it, but Lasky has the ship's AI Roland, who is still loyal to *Infinity*, engage slipspace away from Earth and commit to random jumps until they can develop a way to combat Cortana. With Blue Team recovered, Osiris returns to Sanghelios to reunite the SPARTAN-IIs with an injured Commander Palmer, Thel 'Vadam, and Halsey. If the player completes the game on Legendary, an extra cutscene shows Halo Installation 07 powering up while Cortana hums, before cutting to black.

### Halo Wars 2

Arriving at the Ark, *Spirit of Fire*'s crew receives a UNSC signal from the surface of the installation. Spartan Red Team—composed of supersoldiers Alice, Jerome, and Douglas—is deployed to investigate the signal. They recover Isabel from a UNSC base but are attacked by the Banished during exfiltration. Back on *Spirit of Fire*, Isabel reveals to Captain Cutter how Atriox and the Banished invaded the Ark. Despite Isabel believing resistance hopeless, Cutter declares his intent to confront the Banished. A strike team manages to set up a forward base and defeat Banished forces under the control of Decimus. In the wreckage of Decimus' base, Isabel discovers information about the Ark's Cartographer, a map of key systems and weapons.

The strike team secures the Cartographer, coming under attack by autonomous Forerunner machines known as Sentinels. Anders discovers that Atriox has hijacked the Ark's teleportation network, allowing him to transport troops across the whole structure. The UNSC forces defeat Decimus and disable the portal network. The *Spirit of Fire* comes under attack from a Banished carrier *Enduring Conviction*. The attacking carrier is destroyed when Isabel and Jerome hijack its weapon systems to prompt the Sentinels stationed on the Ark to shatter it in two.

Anders suggests that they create a Halo ring using the Ark's foundry to transport the crew away from the Ark and back into UNSC-controlled space. The new Halo is released but UNSC forces face resistance from the Banished. On the Ark, Alice and Douglas prevent Banished reinforcements, including Atriox, from getting to the Halo. Anders is escorted to the ring's control room where the firing system of the structure is deactivated and a signal beacon is set. Taking control of the ring's gravity systems, Anders releases part of the landmass containing the Banished forces into space, killing them. Having defeated the Banished forces on the ring, ground forces return to the *Spirit of Fire* but Anders and the Halo enter slipspace as they cannot halt the jump's countdown. Before the Halo jumps, Anders promises to get help from the UNSC as soon as possible. Cutter and Atriox prepare for their next engagement. In a post-credits scene, Anders' Halo drops out of slipspace prematurely, only to encounter a Forerunner Guardian.

#### Operation SPEARBREAKER

The *Operation SPEARBREAKER* missions take place one month following the launch of the Halo Ring. The *Spirit of Fire* and the Banished are still fighting for control of the Ark. A UNSC Squad, Sunray 1-1, stumble upon a Banished operation to repair a Forerunner ship and destroy the *Spirit of Fire* with it. Fighting though hordes of Banished forces and Sentinels, Sunray 1-1 is able to narrowly destroy the Forerunner ship before it can launch.

The *Awakening the Nightmare* campaign takes place five months after Operation SPEARBREAKER. The war between UNSC and Banished has reached a stalemate. Desperate for more supplies, Atriox orders the brothers Voridus and Pavium to search near the ruins of the former Covenant holy city of *High Charity* for salvage. Atriox warns them not to enter *High Charity*, believing in the stories of the city having been consumed by the parasitic Flood. The headstrong Voridus ignores the warnings, deactivating the Sentinel defenses and breaching the shield surrounding the city. His rash decision results in the Flood's escape and assimilation of many Banished into the Flood's ranks.

Rather than contact Atriox for assistance and risk his wrath, Voridus claims he can reactivate the Sentinel defenses from another location. The pair activate a drill to propagate natural disasters and hold the Flood at bay temporarily while Voridus leads a handful of troops into a Sentinel base to reactivate the defense network. Voridus succeeds in reactivating the defenses, but the brothers learn that Atriox has learned of their actions and is coming. Atriox warns that he will kill them if they fail to clean up their mess by the time he arrives. Pushing the Flood back to the area surrounding *High Charity*, the brothers discover that the Flood is rapidly developing a coordinating intelligence, a Proto-Gravemind—if it finishes growing, the Flood on the Ark will be unstoppable. The Banished are able to destroy the Proto-Gravemind just as Atriox arrives. He scolds the two brothers and orders them to clean up their mess, but spares their lives. Sentinels flood into the area to deal with the Flood threat along with the Banished, containing the Flood in *High Charity* once more.

### Halo Infinite

In 2559, the UNSC ship *Infinity* is attacked and boarded by the Banished. Atriox defeats the Master Chief and drops him into space. Six months later, a UNSC pilot recovers the Chief adrift in space. While the Pilot wants to flee, Master Chief insists on continuing the fight against the Banished. The Chief and Pilot travel to Zeta Halo, which has been severely damaged by an unknown calamity. On the ring, Master Chief locates the Weapon, an AI designed to imitate Cortana to capture her for deletion. While the Weapon states that she was successful in her mission, she has failed to self-delete as per her directives. Master Chief retrieves the Weapon, and experiences visions of Cortana's memories and thoughts left as residual data.

Zeta Halo is controlled by the Banished, now led by Atriox's lieutenant Escharum after Atriox's apparent death. Master Chief, the Weapon, and a reluctant Pilot rally scattered UNSC forces on the ring's surface. Inside the Forerunner installation known as the Conservatory, Master Chief encounters Despondent Pyre, the AI caretaker of Zeta Halo. Despondent Pyre attempts to warn Master Chief of a threat contained on the installation, but is destroyed by the Harbinger, an alien awoken by the Banished. The Harbinger claims that her people, the Endless, were imprisoned by the Forerunners on Zeta Halo. She has allied herself with the Banished in order to rebuild a facility that will allow her to free her people.

The Pilot reveals that he was a civilian engineer aboard *Infinity* who stole a Pelican to flee the battle. The Chief comforts him, admitting his own guilt over his failure to save Cortana. Master Chief and the Weapon stop Zeta Halo's repair process by disabling a series of spires on the ring. When the Harbinger attempts to hack the Weapon, the Chief activates a failsafe to delete the AI. The Weapon repels the Harbinger and deactivates the failsafe, angrily asking why Master Chief does not trust her. After seeing a vision in which Cortana uses the Guardians to destroy the Brutes' home planet of Doisac, the Weapon realizes that she is a copy of Cortana, and insists that Master Chief delete her so she does not become like her predecessor; Master Chief refuses, stating that he wants to trust her. The Pilot is captured by Jega 'Rdomnai, an Elite Spartan killer and a close friend of Escharum, as bait for Master Chief. Unwilling to let the Pilot die, Master Chief infiltrates the Banished facility and saves him, killing Jega 'Rdomnai and Escharum in the process.

Master Chief and the Weapon rush to stop the Harbinger. The two learn that Cortana was captured by Atriox after the Weapon locked her down; upon realizing that Atriox intended to access the ring's secrets, she destroyed herself, damaged Zeta Halo, and prevented the Weapon from being deleted. In a recorded message, Cortana says goodbye to the Chief and encourages him to work with the Weapon. The Chief defeats the Harbinger, but he is unable to stop her from contacting someone regarding the Endless. Afterwards, the Weapon and Chief reunite with the Pilot, who reveals that his real name is Fernando Esparza. The Weapon decides to choose a name for herself.

In a post-credits scene, a survived Atriox uses a key to unlock a sealed door, leading to the Endless. If the game is finished on Legendary difficulty, the scene features dialogue between Despondent Pyre and the Forerunner Grand Edict about the imprisonment of the Endless. When Despondent Pyre states that she cannot oversee the study of the Endless alone, the Grand Edict replies that the AI Offensive Bias has been deployed to assist her.