SPARTAN-II program

"You have been called upon to serve. You will be trained - and you will become the best we can make of you. You will be the protectors of Earth and all her colonies."

- Dr. Catherine Halsey to the Spartan-II recruits

The SPARTAN-II program was the first proper iteration of the SPARTAN programs, an effort to produce elite soldiers through mechanical and biological augmentation. Originally called the ORION Project, Generation II, SPARTAN-II would be the first in the series to meld advanced exoskeleton technology with the soldiers' superior physiques.

Background
In the years following the deactivation of the original ORION Project in 2506 the effectiveness of small special forces combating the Insurrectionists became too difficult for the UNSC to manage. As insurrectionist forces become more effective and the military's responses consequently become more forceful, the need for large scale military campaigns became more and more obvious.

Around 2510, the Office of Naval Intelligence began to reexamine the Carver Findings, which had warned of instability in the Outer Colonies years earlier. The report rationalized that the instability would continue to escalate, and unless drastic military measures were taken, would result in a massive war between the Inner and Outer Colonies. ONI's own projections at that time and up to 2525 concluded the same as Dr. Carver's findings. Meanwhile, then-eighteen year old civilian scientist Dr. Catherine Halsey had been improving upon Carver's report on her own. Her independent conclusions predicted an even darker future than Carver's model, with UNSC inaction against the rebel leadership resulting in a minimum of thirty years of war and five billion dead; the maximum was a conflict of indeterminate length potentially leading to the downfall of human civilization. Halsey presented her results to Vice Admiral Michael Stanforth of ONI Section III, finding that they had come to the same conclusions. Determined to prevent the predicted carnage, Halsey agreed to work for ONI, specifically Section III's Special Projects Division, on creating a solution.

Creation
Generation II of the ORION Project was initiated in 2511 as the best possible solution to end the widespread insurgency that raged throughout UNSC space. The project was created with several goals in mind. The first goal was to create a group of elite soldiers meant to subdue insurrections in their infancy, without substantial military casualties. The second goal was to minimize civilian casualties and avert civil war. The third goal was to substantially reduce the cost of conventional means of pacification.

Dr. Halsey's proposal for the project detailed radical changes from the original ORION in many different fields. The first and most controversial was the subjects themselves, who were selected by a gene-candidate pool, and must fit into a certain age restriction protocol. They must also have possessed superior physical and mental attributes. The trainees must be instilled with military value, and the understanding of war; something that cannot be taught to enlisted soldiers. This narrowed the candidates down to children who would be raised and taught in the art of warfare and military values, from a young age. Using such controversial means of creating a soldier meant that the project would have to be carried out in the highest form of secrecy.

Though conventional body armor had protected soldiers for centuries, the Gen-II project's second radical change involved integrating the subject with a new powered exoskeleton device, designed to help keep its user safe and provide a powerful means of combating enemy forces. The drawback of this new armor is its requirement for augmenting the subject, effectively turning the participants into human guinea pigs.

Despite the tremendous risk and the unethical means of creating new soldiers, ORION Generation II was greenlit by the top brass within the Office of Naval Intelligence, who concluded that the lives that could be saved far outweighed the risks involved. The project was initially granted funding for 300 candidates, though funding was later reduced to half this number. By 2517, 150 suitable candidates had been identified through DNA gathered from the UNSC's Outer Colony vaccination program, though funding had been further reduced to support only half that number. 75 children, all six years old and of both sexes, were kidnapped. In order to preserve the program's secrecy, the children were replaced by flash clones, which would die soon thereafter due to numerous medical complications associated with flash-cloning an entire human being. Dr. Halsey's use of cloning, following the dissemination of information on the project to the rest of ONI, came to be regarded one of the most controversial decisions involved with the program. In particular, the decision drew the anger of Admiral Margaret Parangosky, Commander in Chief of ONI, who interrogated Halsey after her capture and demanded to know her reasoning for the use of flash clones. Parangosky viewed the clones as unnecessary, maintaining that Halsey replaced the abductees with clones for personal, moral reasons, believing that she was giving the families closure and thus easing her own conscience.

Halsey was not satisfied with the project's original name of ORION Project, Generation II; thus, she renamed it out of personal preference, as well as to distance the project from the failures of ORION in the minds of the politico and military bureaucrats who controlled the project's budget. In order to pay homage to the sacrifice of the ORION project, she chose to call the project SPARTAN- II. She considered several other "bellicose" names, including Praetorians, Landsknecht, Immortals, Minutemen, Titans, Argonauts, Odysseus, Olympians, Zulu, Kronos, Promethean, Armor, Nemesis, Daedalus, Hercules, Viking, and Hyperion; the latter two were quickly excluded.

Training


After being kidnapped and sedated, the Spartan-II candidates were taken to the colony world Reach, where they began their training under Chief Petty Officer Franklin Mendez and the AI Déjà, who also acted as an aide for Halsey on the program. To marginalize the civilian lives they had once led, their names became a combination of their given names and a number, with family names being discarded. Based mainly within the Reach FLEETCOM Military Complex, the Spartans endured a great deal of hardship during their first years of training: they were placed into situations and drills that pushed their abilities to their very limit and beyond. Their hard training was complemented with high-level education, which included mathematics, science, history, reading, writing, and military tactics.

Although his training methodology was tough, even brutal in some regards, Chief Petty Officer Mendez always instilled discipline, honor, and respect into the Spartans. He taught the Spartans how to kill, but at the same time he taught them the difference between right and wrong. During this time, John-117 rose to be the de facto leader of the Spartans. Mendez trained the Spartans until 2525 when, at the age of fourteen, the they would go through the toughest part of their training: the biological augmentation procedures, which would kill 30 of the 75 conscripted children and cripple twelve others who would "wash out" of the SPARTAN-II program, going on to join the Office of Naval Intelligence. Only 33 survived the procedures without physiological deformities, of whom two would commit suicide in the following weeks upon encountering their flash clones. The bodies of those candidates who "washed out" were placed in cryonic suspension in the hope that they could some day be resuscitated. At least some of the candidates who were crippled may have been physically rehabilitated in later years.

Human-Covenant War
The Human-Covenant War marked a change in objectives for the program; originally intended to quell rebellions, the Spartans were now forced into battle against a superior opponent to the insurrectionists: the Covenant. This new threat accelerated the Spartans' training to its final phase: Project MJOLNIR. With the Mjolnir armor, the Spartans would be the first major UNSC response to the alien threat. The Spartans continuously proved highly effective against all threats; their heroic rearguard and delaying actions saved countless human lives from the genocidal Covenant onslaught. In 2547, the SPARTAN-II program was revealed to the public in an effort to boost morale among the UNSC. The Spartans' prowess was not lost on the Covenant, who came to fear, and in the case of the Sangheili, respect the Spartans as Demons.

Inevitably the small number of Spartan-IIs dwindled as casualties were sustained. As the exploits of the Spartans were a major propaganda boom to the UNSC, Section II of the Office of Naval Intelligence issued Directive 930, which stated that Spartans killed or wounded would be listed as "missing in action" (MIA) or "wounded in action" (WIA), thus maintaining the illusion of the Spartans' invincibility. By August 27, 2552, 25 of the 28 remaining Spartan-IIs assigned to NAVSPECWEAP,   except Gray Team, had been recalled to Reach, some from combat, to receive new orders for Operation: RED FLAG, a mission that HIGHCOM hoped would end the war. They would commandeer a Covenant vessel, locate the Covenant homeworld, and return with captured Covenant leadership to force a ceasefire. The artificial intelligence construct Cortana, carried within John-117's Mark V Mjolnir armor, would serve as the strike force's hacker and technology specialist.

However, all preparations were interrupted and subsequently canceled by the Covenant's invasion of Reach. In the ensuing disaster, most of the Spartan-IIs were killed, although some took shelter in ONI's CASTLE Base. Two escaped aboard the, one of whom was place in cryostasis aboard the ship after sustaining life-threatening injuries during the battle on Gamma Station. The Pillar of Autumn soon arrived at Halo Installation 04, which John-117 ultimately destroyed to prevent the spread of the Flood. Following the Battle of Installation 04, the survivors returned to Reach and were able to rendezvous with the remaining Spartans. The survivors then carried out a raid that resulted in the destruction of a Covenant fleet anchorage, stalling a Covenant plan to invade Earth. SPARTAN-IIs would go on to play pivotal roles in the Battle of Earth, the Battle of Installation 05, the Battle of Onyx, and the Battle of Installation 00. Ultimately John-117 would eliminate the Covenant leadership with the help of the Flood and Thel 'Vadam, effectively defeating the Covenant and ending the war. However, he ended up trapped in space on the back half of the and was declared missing in action.

Post-war
Only nine Spartan-IIs are known to have survived the Covenant War: John-117, Fred-104, Kelly-087, Linda-058, Naomi-010, Otto-031, Victor-101, Margaret-053, and Roma-143; the last four have since been killed. Others, such as Gray Team and an early incarnation of Red Team (Douglas-042, Jerome-092 and Alice-130) were alive but out of contact with the UNSC as of their most recent sightings; the status of these Spartans following the war remains unknown, although it has been noted that many Spartan-IIs initially believed dead or MIA have since returned to contact with the UNSC. Following the ceasefire, the surviving Spartan-IIs were offered the choice of integrating into the newly formed Spartan branch along with the remaining Spartan-IIIs. However, at least Blue Team remained under NAVSPECWAR's operational command by 2557. Some Spartan-IIs are known to have taken part in the training of Spartan-IV personnel.

In 2557, John-117 played a pivotal role in the new galactic conflict, stopping the Ur-Didact's attack on Earth after linking up with the on Requiem after being missing in action for nearly five years. John subsequently reunited with Blue Team who faced the Didact again shortly afterward; after defeating the Promethean for the second time, the team continued to serve in the field in a number of classified operations. Team Black was stationed on Installation 03, until they were killed by the Didact, dwindling the known number of active Spartan-IIs down to five.

Personnel
"Die? Didn't you know? Spartans never die."

- Lieutenant Commander Kurt Ambrose to Fleet Master 'Mantakree, referencing ONI Directive 930

Publicity
ONI publicly unveiled the Spartans on May 21, 2547 in order to boost morale, though the supersoldiers' true origins remain classified to the general public as of 2558. The 2547 CAA Factbook entry on the Spartans states that the supersoldiers are "recruited from all corners of UNSC governed space" and that "each of them is a highly decorated veteran with literal decades of combat experience", but omits the program's ethically problematic background. At least John-117, who was elevated to a legendary status as the "Master Chief" in the final months of the war, was given an elaborate, inspiring origin story to hide his true background, promoted by several individuals claiming to have known or interacted with John at some point. However, as of 2553, there were pervasive rumors among the UNSC military that the Spartans had been kidnapped as children. Admiral Parangosky planned to unveil the SPARTAN-II program's classified aspects to the UEG defense committee by early 2553, although any information on the Spartan-IIs origins remained unconfirmed among military personnel as of 2555. The information is not public knowledge as of 2558, although some of the Spartan-IVs were made aware of their predecessors' origins. At some point in 2558, journalist Benjamin Giraud uncovered the origins of the program and uploaded his findings to the public network, along with delivering an unsanctioned testimony on the matter to the Unified Earth Government Senate's Armed Forces Committee. This compounded an increasing distrust against ONI and the Spartans generated by a recent attack on a peace conference apparently perpetrated by the Master Chief.

The identities of the Spartans' full names have been deleted from all military records. Only Dr. Halsey had secret files that contained the full names of all the Spartans on Reach; unfortunately, the records were destroyed after the the planet was glassed. The only other copy of these records is in the possession of Admiral Margaret Parangosky. Within the military and to the public the Spartans are only known by their service tags, consisting of "SPARTAN" followed by a numerical ID; only a select few outsiders know even their first names.

Psychology
The Spartan-IIs' training emphasized dedication to one's duty as well as winning at any cost, values most of the active Spartan-IIs remain committed to. They frequently ignore concerns over their personal health as long as there remains a mission to complete and have shown to become incredibly frustrated when prevented from acting in a combat situation; because of this they prefer planetary operations to being based aboard starships with no way to contribute to an engagement.

The Spartan-IIs enjoy a great deal of solidarity and camaraderie within their group due to them having grown up together; indeed, they consider their fellow Spartans family, something that was encouraged in their indoctrination from a young age. Having been taught to refrain from overt emotional displays, the Spartan-IIs most commonly convey their emotions through subtle body language and cryptic gestures. They possess numerous unique internal habits and signals conveyed through simple gestures or statements, making interactions among their group largely indecipherable to outsiders. Only a select few outsiders, including Dr. Halsey and Déjà, are privy to some of the best-held secrets within the group. Their familiarity with each other's body language allows the Spartan-IIs to function in perfect synergy in combat, their teamwork abilities having been described as borderline telepathic. Although the Spartan-IIs often have difficulty socializing with baseline humans outside situations of a strictly military nature, they are rather gregarious among themselves and habitually cluster together while out of the battlefield, commonly engaging in activities such as playing cards, exercising together, reading, or maintaining their personal equipment.

Most humans view the Spartan-IIs with awe, sometimes even revulsion, due to both their reputation and intimidating presence, the latter complemented by the seemingly unnatural speed, precision and grace of their movements. Few outsiders are willing to as much as touch a Spartan, such as shaking one's hand.

Organization
The majority of the Spartan-IIs serve under Naval Special Weapons, a division of the UNSC Special Forces with heavy ties to Section Three of the Office of Naval Intelligence, which initiated and operated the SPARTAN-II program. This remains unchanged despite the formation of the new Spartan branch in the post-war era. All Spartan-IIs graduated to the rank of petty officer second class at the conclusion of their training, though many have since risen to a higher rank.

The Spartan-IIs enjoy a large degree of operational autonomy in the field and typically operate in teams of three to five and even individually, although the size and composition of these teams is heavily mission-specific; a team leader will typically pick the Spartans best suited for the mission at hand according to their personal talents. However, with the original Spartan-II group dispersed across the battlefields of the Covenant War over the decades, certain team arrangements became more established than others. Spartan-II teams are assigned color-based designations on a mission-specific basis, Blue and Red teams being the most prominent of these. On some missions, Red Team has formed smaller splinter units (designated with Greek alphabet) to better suit the mission objectives at the time. Some Spartan-II teams appear to have been more well-established since their training, namely Black and Gray teams which continued to operate with their compositions unchanged over the Covenant War.

Class I
The following is the list of all known Spartan-II subjects conscripted in 2517. Of the 150 children considered for the program, only 75 were conscripted. Carris-137's status after September 2520 is unknown. The only known candidate who was not conscripted was Candidate 095: Caleb F. Aagard.

Successfully augmented
Deceased Spartans are assumed to be officially listed missing in action or wounded in action, even if known with certainty to be KIA. This is for morale purposes, to enable the claim that no Spartan has ever been killed. Those who truly are missing are listed as such.

Discharged
Twelve Spartan-II candidates were discharged from the program after failing the augmentation procedures, most becoming severely crippled. The majority of these former candidates were later reassigned to the Office of Naval Intelligence. However, Dr. Halsey hoped that some might be rehabilitated and enter service as fully functional Spartans.


 * Kirk-018 - Discharged. Possibly rehabilitated, for which Halsey had expressed hope.
 * Maria-062 - Retired active duty and assigned to UNSC reserves. Last seen working at SWC Songnam in October 2552.
 * Soren-066 - Discharged due to failures in augmentation process in 2527. Listed as missing in action on Reach after defecting to the insurrectionists. Presumed killed before or during the Fall of Reach.
 * Cassandra-075 - Discharged due to failures in the augmentation procedures in 2525. Residing on the M25L Recovery Station as of October 2552.
 * René-081 - Discharged after "washing out". Possibly rehabilitated, for which Halsey expressed hope in her journal.
 * Fhajad-084 - Discharged and reassigned to ONI. Suffered uncontrollable muscle spasms due to failures in augmentation. Current status unknown; possibly rehabilitated, for which Halsey had expressed hope.
 * Musa-096 - Forced into a wheelchair for the rest of his life due to the augmentation procedures. Later became a commander and one of the creators of the SPARTAN-IV program.
 * Ralph-103 - Failed to adapt fully to augmentations; discharged due to experiencing irreparable psychological trauma after escaping the program in 2525. Later joined the UNSC Marine Corps. Killed in action during the Harvest campaign in early 2531.

Fatalities
Officially, thirty Spartan candidates were killed when they failed to adapt to their physical enhancements; the only identified fatality was SPARTAN-073. However, at least five of the candidates allegedly killed by the augmentation procedures actually lived and were pressed into ONI service, their survival kept secret from their peers. Serin-019 became an ONI operative while the four-member Black Team came to perform high-risk, low-oversight missions in hostile territory, also under ONI jurisdiction.

This was presumably made possible by Halsey's insistence that no invasive autopsies be performed and that the funeral for those killed by the procedures be closed-casket, the cadavers instead remaining in cold storage. The doctor considered that some of the deceased Spartans may some day be resuscitated and placed into active service; by June 27, 2525, rehabilitation protocols were in development for 80% of the washouts, with AIs predicting a total survival rate as high as 50%. Halsey also noted her consternation over what ONI may do with a secret team of officially deceased Spartans, coincidentally predicting Black Team's survival.


 * Serin-019 - Rejected most physical augmentations; physical damage largely repaired by ONI. Recruited as an ONI field agent, adopting the surname "Osman". Later became the protégé of Admiral Margaret Parangosky and was handpicked by the latter to lead the black ops team Kilo-Five. Serves as Commander-in-Chief of the Office of Naval Intelligence as of September 2558.
 * Otto-031 - Confirmed KIA on Installation 03 (7/25/2557).
 * Margaret-053 - Confirmed KIA on Installation 03 (7/25/2557).
 * Victor-101 - Confirmed KIA on Installation 03 (7/25/2557).
 * Roma-143 - Confirmed KIA on Installation 03 (7/25/2557).

Class II
After the graduation of the first class of Spartan-IIs in 2525, Dr. Halsey began planning for the next wave of Spartans; her efforts, however, ran into problems. There were too few candidates that were in sync with her age and genetic restriction protocols and a majority of her funding was going towards Mjolnir maintenance and construction; this left little room for continued training efforts. By 2531, the majority of her funds had been diverted to other projects, most notably the top-secret, eyes-only SPARTAN-III program. Halsey eventually gave up on Class II and left the program, after she judged the candidates to be of an inferior standard.

Around six years later, however, enough candidates were within the right age range to begin a second class. One of the most notable candidates, six-year-old Yasmine Zaman, was abducted and replaced by a flash clone. However, she died during the augmentation procedures. Among those who survived was Nicole-458. Another girl, Janissary James, was selected as a suitable candidate for training. However, her father, an ORION Project member now known as "James James", killed the would-be kidnapper.

ONI Directive 930
In order to maintain morale among the other forces of the UNSC, the Office of Naval Intelligence created Directive 930. According to it "any Spartan casualties are to be listed as Missing In Action (MIA) or Wounded In Action (WIA), but never Killed In Action (KIA)." The protocol is not applied to members of the SPARTAN-IV program and the Spartan branch, the UNSC opting to honor their sacrifices accordingly rather than maintaining an aura of invincibility for propaganda purposes.

Project MJOLNIR
The Mjolnir armor was created in parallel to the SPARTAN-II project and is the most technologically advanced piece of hardware in human hands. It can provide a Spartan with an incredible amount of protection and strength. The onboard computer system relays basic tactical information including IFF tags, a motion tracker, weaponry information, and health and energy shield level readouts. Later models of the Mjolnir system are capable of carrying a starship-grade AI which can provide tactical data in the field.

Specialized neural interface
This specialized version of the neural interface is implanted into the skull of a Spartan-II. The standard neural interface provides the neural link between the Spartan-II and the Mjolnir armor. This device allows a starship-grade AI to be carried "between" the host's brain and later models of the Mjolnir armor. John-117 was outfitted with this upgrade due to his need to carry the AI Cortana on a mission to capture the Covenant leadership.

Spartan augmentation procedures
One of the essential and most dangerous aspects of the SPARTAN-II program was the biological augmentation procedures. The process consisted of many injections and surgeries. Only a small percentage of subjects survived the process and fully recovered.

Facilities
The SPARTAN-II program was based in a dedicated compound within the Reach FLEETCOM Military Complex. Most of the Spartans' training was carried out in the various facilities within the complex as well as the surrounding wilderness of Reach's Highland Mountains, with classroom sessions provided by Déjà in the Reach Naval Academy. They were also given training in various offworld locations, including Emerald Cove and Chiron Station. The SPARTAN-II augmentation procedures were conducted in an ONI medical facility in orbit over Reach.

Halo Wars
"Summoning a Spartan to the battlefield is not a guarantee of victory, nor is it something to be taken lightly. It requires a significant investment of time and energy to field Spartans, so they’re not a commonplace sight. When they do end up on the scene though your opponent will have to learn to take the threat of a Spartan on the battlefield seriously, or suffer the consequences."

- Halo Wars website

In Halo Wars, Spartan-IIs are infantry units for the UNSC faction. They can be built from a Barracks and are perhaps the most versatile units in the game. A Spartan is equipped with energy shields, can wield different weapons, command friendly vehicles, hijack enemy ones, and gain up to 14 veterancy points while other units cap at 3. Any vehicle piloted by a Spartan gains an extra 15% to their defense and damage, with additional stat boosts for every upgrade the Spartan has.

Spartans cost 300 resources each and requires a tech level of 1. Only three can be deployed for an army but they do not take up population. By default they are equipped with a pair of submachine guns. Spartans can receive the following upgrades.


 * Chaingun: 300 resources and a tech level of 2. Equips an AIE-486H Heavy Machine Gun for increased damage.
 * Neural Implant: 600 resources and a tech level of 3. Allows Spartans to jack enemy vehicles quicker.
 * Spartan Laser: 1,000 resources and a tech level of 4. Gives Spartans more range to their attacks and lets them deal out more damage.

In the campaign, Spartan Red Team is recruited on Arcadia and available for all missions after Arcadia City. They count as hero units and therefore cannot be killed, only knocked out and slowly healing until they are revived. By default Jerome-092 wields a Spartan Laser, Douglas-042 uses a rocket launcher, and Alice-130 uses a chain gun. Six more Spartans are available during the mission Arcadia Outskirts, identified as Team Omega.

Trivia

 * The SPARTAN-II seal closely resembles the modern Seal of the President of the United States. The Halo 3 achievements "UNSC Spartan" and "Spartan Officer" are represented by the SPARTAN-II seal. A cloth patch bearing the SPARTAN-II program's insignia is included with the Limited and Legendary Editions of Halo: Reach.
 * The SPARTAN-II program is reminiscent of the Adam Project depicted in the 1998 film Soldier. Both feature children brutally trained and indoctrinated (in the film, the candidates are selected as infants) to become stoic and ruthless commandos to be deployed against human insurgents. The Spartans' naming also echoes that shown in the film: a first name followed by a numeric designation (Soldier ' s protagonist is named Todd 3465). Certain aspects of the soldiers' training also show close similarities; in the film, the children are forced to watch a pack of dogs devouring a boar whereas in Halo: The Fall of Reach, the Spartans are shown a display of wolves hunting a moose.

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * i love bees
 * Halo 2
 * Conversations from the Universe
 * Halo Graphic Novel
 * The Last Voyage of the Infinite Succor
 * Armor Testing
 * Halo: Ghosts of Onyx
 * Starry Night
 * Believe
 * Diorama
 * Halo: Uprising
 * Halo 3
 * Halo: The Cole Protocol
 * Halo Wars
 * Halo: Helljumper
 * Halo Legends
 * Origins
 * Homecoming
 * The Babysitter
 * The Package
 * Odd One Out
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Pariah
 * Dirt
 * The Mona Lisa
 * Palace Hotel
 * Human Weakness
 * Halo: Blood Line


 * Remember Reach
 * Deliver Hope
 * Halo: Reach
 * Data pads
 * Dr. Halsey's personal journal
 * Halo: Fall of Reach
 * Boot Camp
 * Covenant
 * Invasion
 * Halo: Glasslands
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: The Thursday War
 * Halo 4: Forward Unto Dawn
 * Scanned
 * Halo 4
 * Spartan Ops
 * Halo: Initiation
 * Halo: Escalation
 * Halo: Mortal Dictata
 * Halo: Broken Circle
 * Halo: Nightfall
 * Halo 2 Anniversary
 * Terminals
 * Halo: New Blood
 * Hunt the Truth
 * All Hail
 * The Cost
 * Hunt the Signal
 * Halo: Spartan Strike
 * Halo: Fleet Battles
 * Halo: Last Light
 * Halo: The Fall of Reach - The Animated Series
 * Halo 5: Guardians
 * Halo Wars 2