This article is about the game mode. For the military branch, see Spartan Operations.
Spartan Ops allows up to four players to play cooperatively. Though it is designed primarily as a cooperative experience, Spartan Ops can be played solo as well. It follows the SPARTAN-IV units Fireteam Majestic and Fireteam Crimson, with the players assuming the role of the latter while the former features in the CGI cinematics. Set six months after the campaign, Spartan Ops expands on the story of the UNSC Infinity and her crew. Due to its scope and scale, this new mode has been likened to a second campaign for the game.
Frank O'Connor has stated that the mode will "bridge the gap" between the events of Halo 4 and the future release of its sequel. 343 Industries will support additional Spartan Ops missions for months after launch of the game and players will have the opportunity to play from the beginning of the episodic campaign regardless of when they started playing. The first season is included with the game, though 343 Industries have not ruled out charging players for additional Spartan Ops seasons. There are no plans for a second season of Spartan Ops. However, Frank O'Connor has stated that "the story of Crimson, the Infinity and those characters and events is far from over". Indeed, the comic series Halo: Escalation follows largely the same cast of characters a month after the events of Spartan Ops.
Each episode is accompanied by an episode of Halo: Infinity, a computer-animated series that follows the crew of the UNSC Infinity. Produced by the Scottish studio Axis Animation, the series' point-of-view alternates primarily between the ship's command crew and Spartan Fireteam Majestic. The events of the series intertwine directly with those of the cooperative missions, which in turn carry the story forward to the next episode. Those without an Xbox LIVE account may view the Halo: Infinity series on Halo Waypoint, Waypoint's YouTube channel or the Halo Channel.
Spartan Ops follows an ensemble cast of both new and preexisting characters.
In February 2558, the UNSC Infinity is dispatched to reclaim Requiem from the occupying Covenant forces. Once there, Infinity engages in combat with the Covenant fleet, and deploys ground forces, including Fireteams Majestic and Crimson as well as detachments of Marine, Navy, Air Force and Army forces on Requiem. The Spartan fireteams run through a series of search and destroy, rescue, artifact recovery, extraction and assassination operations.
During a mission on the surface, Fireteam Crimson uncover a Forerunner slipspace artifact which is subsequently brought aboard Infinity. After the device disrupts the ship's systems and teleports Chief Engineer Glassman to the surface of the planet, Dr. Catherine Halsey is brought in to investigate. The artifact scans the ship's systems and begins transmitting data to the surface of Requiem, where said data is intercepted by Jul 'Mdama. Glassman is taken captive by his Covenant and is ordered to activate the Librarian's shrine, though he is not successful.
Fireteam Crimson secure another Forerunner artifact, dubbed "the Didact's Gift". This device is revealed to contain the memories of victims of the Didact's attack on New Phoenix six months prior, revealing that the composed human minds have been repurposed as Promethean Knights. Investigating the first artifact on his own, Spartan Gabriel Thorne is translocated to the Cauldron and is left to fend for himself amidst Covenant-controlled territory. Dr. Halsey begins dialog with an unknown party who shares her interest in the Librarian. The intelligence is actually Jul 'Mdama, who is manipulating Halsey into divulging vital secrets about the Forerunners. Halsey is apprehended after her unwitting communication with 'Mdama is discovered. Meanwhile, Spartan Thorne rescues Dr. Glassman and the pair escape custody.
After Dr. Halsey briefly escapes imprisonment and resumes her communication with 'Mdama, Infinity is boarded by Covenant and Promethean forces who capture Dr. Halsey. They take her to the Librarian's "shrine", where 'Mdama awaits. Meanwhile, Admiral Serin Osman, head of the Office of Naval Intelligence, orders Captain Lasky to assassinate Dr. Halsey; Commander Palmer departs to execute the order. However, Lasky sends Fireteam Majestic to rescue Dr. Halsey and stop Palmer. Meanwhile, Dr. Halsey successfully activates and enters the Librarian's shrine. The Librarian's essence gives Dr. Halsey an artifact known as the Janus Key, but Jul 'Mdama gets one half of the key. Halsey tosses Gabriel Thorne the other half before she is abducted by 'Mdama.
Believing to have obtained what they were looking for, Jul 'Mdama sends Requiem to be destroyed by a nearby star. Deactivating a slipspace anchor originating from Requiem, the UNSC Infinity narrowly escapes the planet's gravity well. Afterwards, Lasky and Palmer observe as Dr. Glassman studies one half of the divided Janus Key. Meanwhile, aboard a Covenant ship, Dr. Halsey seemingly agrees to collaborate with Jul 'Mdama and his forces, stating that she wants revenge.
Each week, players with an Xbox LIVE Gold membership were able to view a new episode of Halo: Infinity, which was then followed by five objective-based missions. The missions offered new content, as well as challenges to complete for each week.