Halo 3

Halo 3 is a first-person shooter video game in the Halo universe and the end of the Halo trilogy. It was developed by Bungie Studios and published by Microsoft.

Campaign
On November 17 2552, two weeks after the events of Halo 2, John-117 plummets through Earth's atmosphere using a fragment of the Forerunner Dreadnought he was last seen on in Halo 2. He crashed into an east African jungle, soon after being found by Sergeant Major Avery Johnson on a rescue mission to collect the Chief. Johnson, Arbiter Thel Vadam and a handful of Marines, head toward the extraction point. Covenant forces are sighted in the area and Johnson splits the group to reduce their chances of getting spotted. John and Thel continue on their way to the extraction zone with the second squad, fighting off numerous Covenant troops in the process, but upon reaching the extraction point, Johnson's Pelican group consisting of two Pelicans, are ambushed and shot down by Banshees. Johnson and his men are then captured and taken prisoner by a number of Brutes led by a Brute Chieftain. John, Thel and company fight their way through hordes of Covenant and eventually rescue them, after which a Pelican piloted by Hocus arrives and picks them up.

The Pelican brings them to Crow's Nest which is used as a local base of operations by the UNSC. Here, Commander Miranda Keyes and Lord Hood plan a last-ditch effort to stop the Covenant from activating a Forerunner artifact known as the Ark, uncovered outside the ruins of the city of New Mombasa. If activated, this artifact will activate the Halo Array and wipe out all sentient life in the galaxy. Their plan is to have John and a small group of Marines punch a hole in the Prophet of Truth's anti-air defenses, so that Hood can initiate a low level air-strike on the artifact. Their planning is quickly interrupted when power is cut and Truth broadcasts an announcement to all surviving human forces that their doom is inevitable. Soon after that, the Covenant forces discover the facility and mount a heavy assault. After a brief struggle, the outpost is lost and is destroyed by a bomb activated by John. Deep underground, John regroups with the surviving Marines and makes his way into the African City of Voi, Kenya via the Tsavo Highway. Sometime afterward, John along with a handful of Marines destroy the Covenant anti-air defenses, Hood leads the last of Earth's military ships against Truth and the artifact. As Hood mounts his attack on the Prophet, Truth activates the artifact and creates an enormous slipspace portal, into which all the Covenant ships retreat.

At the same time, a Covenant cruiser controlled by the Flood arrives suddenly via slipspace and crashes in Voi, the parasite quickly spreads throughout the entire city. As the human forces attempt to fight the infestation, many are infected by the Flood. The Fleet of Retribution division within the Covenant Separatists, led by Shipmaster Rtas Vadum, arrives at Earth and assists the struggle against the infestation. The Elites inform Miranda that a UNSC construct is aboard the crashed Flood ship, and identified it as Cortana. After retrieving Cortana, John returned to the Shadow of Intent to oversee the repairs made by 343 Guilty Spark. However, it is only a recorded message from her. Cortana's message says that the Gravemind is coming to Earth with an army of Flood, and that on the other side of the portal is a solution to the Flood infestation, without having to fire the rings. Hood questions Cortana's plan, assuming that it could be a Flood trap, but John firmly tells Hood that he trusts her.

Hood and his UNSC forces remain on Earth to defend it against the incoming Flood invasion while Miranda, John and the Elites journeys through the portal. Arriving at the Ark, the Covenant Separatists engages the Covenant fleet while the UNSC launches a ground campaign. After landing on the Ark, Spark helps lead John and UNSC forces to the Ark's Catographer, the map room of the Ark, to locate the control room. In order to access the control room, the UNSC and the Covenant Separatists must deactivate three shield generators which are inside three separate towers. While John and Thel succeed in deactivating the first and second towers, Johnson radios Miranda, telling her that he must retreat due to the heavy enemy assault. When John and the Elites arrived at the third tower, Johnson and his men are nowhere to be seen. After the final shield barrier protecting the control room deactivates, the Flood-infested High Charity arrives via slipspace and crashes onto the Ark, releasing many Flood dispersal pods and flood-infested rocks as it falls, causing the Covenant to be even more prone to lighting the rings.

After handling the nearby infestation, John leads the remaining UNSC and Elite forces via armored vehicles in an assault on the Citadel containing the control room, which is heavily defended by Covenant forces. Once inside the Citadel, Truth broadcasts his sermon and reveals the captured Johnson to his followers. Just as Truth is about to force Johnson to activate the rings, Miranda crashes into the control room using a Pelican. Knowing she can't kill all the Brutes, Miranda realizes that she must kill Johnson and herself to stop the rings from being activated. From behind, Truth kills Miranda with a Spiker, and then forcing Johnson's hand on the nearby terminal, activates all of the remaining Halos in the galaxy.

Just as John and Thel reach the top, the Flood confront them. The Gravemind, communicating through the Flood, urges the two to join forces in stopping the initiation of the Halos and Truth. The Flood help John and Thel reach Truth, taking out the Covenant defenses. With the Flood's help, John and Thel slaughtered all of the Covenant forces defending Truth. Upon arrival to the Ark's control terminal, they find Johnson mourning over the loss of Miranda, and Truth partially infected. Thel, after a short confrontation with Truth over the purpose of the Halos, executes Truth with his Energy Sword, claiming he is too dangerous to be kept alive, just as John deactivates the rings. Shortly after the destruction of the Halos, the Gravemind betrays them and prevents the duo from escaping, although Johnson manages to escape using Miranda's crashed Pelican.

John and Thel manage to escape from the Citadel via an access tunnel near the elevator they used earlier. John then experiences a hallucination of Cortana and follows the figure to a control panel. He then activated the panel, surprised to see the Ark was manufacturing a replacement Halo after the destruction of the previous one. Knowing that the threat of the Flood is undeniably apocalyptic, John decides he will activate the new Halo. Needing an Index in order to fire the ring, John journeys into the crashed High Charity to retrieve Cortana, keeping his promise and knowing that she still has the Index she acquired from the original Installation 04. Once retrieved, Cortana instructs John to overload High Charity's engines in order to destroy the Gravemind. Thel arrives via Banshee to assist John in fighting the Flood. The two escape from High Charity before it explodes using a damage but still working Pelican.

The surviving Elites and UNSC personnel return to Earth, leaving only Sergeant Johnson, John with Cortana and Thel to make their way to the new Halo. As they make their way to the new Halo's control room, the Flood arrive via dispersal pods to prevent the activation of the Halo. From here, they quickly discover that the Gravemind is attempting to reconstruct itself on the new Halo. As Johnson tries to activate the ring, Spark fires his defensive laser at him, mortally wounding Johnson, after realizing that it will destroy the installation. The Monitor then turns against John and Thel, blasting the Arbiter out of the control room, leaving the Spartan to fight Spark by himself. John successfully destroys Spark and tries to mend Johnson. Mortally wounded, Johnson urged John to send him out with a bang.

With the Halo activated, John and Thel race towards the frigate Forward Unto Dawn using Johnson's Warthog. With no time to reach the cockpit, John uploads Cortana into the frigate to start taking off before Thel is able to take the controls. The front half of the Dawn, containing the Arbiter, makes it through the portal. However, as Halo shakes itself to pieces during it's firing sequence and damages the Ark, the portal deactivates as the other half of the frigate containing Chief and Cortana enter it. This causes them to rip off from the other half of the ship and be sent to an unknown area of space far enough from the Halo's blast, however, since they didn't come out of the other side of the portal, they never made it back to Earth.

Back on Earth, Hood holds a memorial service in honor for those who died in the Human-Covenant war, with Thel and many Marines in attendance. With Truth dead, the Covenant defeated and the Flood wiped out, the long and devastating war is finally over. Though he says he can never forgive the Arbiter for what the Covenant did to the human race, Hood sincerely thanks Thel for standing by John until the end. After the service, the Covenant Separatists returned to their homeworld.

After the credits, it is revealed that John and Cortana are still alive aboard the rear section of the Dawn, which had apparently torn off before going through the other side of the portal. John floats to a cryotube and as he climbs in, Cortana comments she'll miss him. He replies that if his needed, she should wake him up. In the Legendary ending, they are seen drifting towards Requiem.

Characters

 * Master Chief Petty Officer John-117:
 * Arbiter Thel Vadam:
 * Cortana:
 * Sergeant Major Avery Johnson:
 * Lieutenant Commander Miranda Keyes:
 * Shipmaster Rtas Vadum:
 * 343 Guilty Spark:
 * Gravemind:
 * Prophet of Truth:
 * Fleet Admiral Terrence Hood:
 * N'tho Sraom:
 * Usze Taham:

UNSC

 * Magnum:
 * Battle Rifle:
 * Assault Rifle:
 * SMG:
 * Rocket Launcher:
 * Shotgun:
 * Sniper Rifle:
 * Spartan Laser:
 * Frag Grenade:
 * Heavy Machine Gun Turret:
 * Missile Pod:
 * Flamethrower:

Covenant

 * Plasma Rifle:
 * Plasma Pistol:
 * Needler:
 * Covenant Carbine:
 * Beam Rifle:
 * Fuel Rod Cannon:
 * Energy Sword:
 * Gravity Hammer:
 * Spiker:
 * Brute Shot:
 * Mauler:
 * Plasma Grenade:
 * Spike Grenade:
 * Firebomb:
 * Shade Turret:
 * Plasma Turret:

Forerunner

 * Sentinel Beam:

Equipment

 * Bubble Shield:
 * Power Drain:
 * Trip Mine:
 * Portable Gravity Lift:
 * Radar Jammer:
 * Flare:
 * Regenerator:
 * Deployable Cover:
 * Invincibility:
 * Automated Turret:
 * Cloaking:
 * Active Camouflage:
 * Overshield:
 * Custom Power-Up:

UNSC

 * Warthog:
 * Guass Warthog:
 * Troop Warthog:
 * Mongoose:
 * Scorpion:
 * Hornet:
 * Elephant:

Covenant

 * Ghost:
 * Wraith:
 * Banshee:
 * Anti-Air Wraith:
 * Chopper:
 * Prowler:

Non-Usable

 * Charon-class Light Frigate:
 * Pelican:
 * Albatross:
 * Longsword:
 * Tractor Unit:
 * Cart:
 * Forklift:
 * CAS-class Assault Carrier:
 * CCS-class Battlecruiser:
 * Forerunner Dreadnought:
 * Phantom:
 * Scarab:
 * Seraph:
 * High Charity:
 * Flood Dispersal Pod:

UNSC and Humans

 * Marine:
 * ODST:
 * Voi Factory Worker:

Covenant

 * Elite:
 * ​Minor:
 * Major:
 * Ultra:
 * SpecOps:
 * Brute:
 * ​Minor:
 * Major:
 * Ultra:
 * Stalker:
 * Jump Pack:
 * Bodyguard:
 * Captain:
 * Captain Major:
 * Captain Ultra:
 * Chieftain:
 * War Chieftain:
 * Hunter:
 * Grunt:
 * ​Minor:
 * Major:
 * Heavy:
 * SpecOps:
 * Jackal:
 * ​Minor:
 * Major:
 * Sniper:
 * Drone:

Forerunners

 * Sentinel: 
 * Constructor:

Flood

 * Infection Form:
 * Combat Form:
 * Carrier Form:
 * Tank Form:
 * Stalker Form:
 * Ranged Form: