When it does, the series will have plenty of tie-in stories to choose from. With a plot set in the 26th century and confirmed to include Master Chief, only one era is completely off-limits—the Forerunner era, the prehistory that set off the events in Halo 4 and featured in a dreamlike series of books by science fiction veteran Greg Bear. But there are still plenty of stories to work with. Here are the stories the showrunners may use as inspiration for the new series:

Blue Team 

The viewpoint characters for a lot of the Spartan experience is Blue Team, a squad made up of Master Chief’s closest friends. A show focusing on them would give fans characters they recognize from both Halo 5 and years of tie-in material. This would also be a good opportunity to explore Master Chief’s personality and how he acts in a group with the people with whom he is most comfortable. Halo has always been about teamwork and sacrifice, and Blue Team has those things in spades. 

Sergeant Johnson 

Third only to Master Chief and Cortana in terms of recognizable characters from Halo: Combat Evolved is Sergeant Johnson, provider of military bravado and drill sergeant one-liners aplenty. A show that follows Johnson during the Covenant War would include some of the most recognizable moments in the classic games and could expand on them—and would have a very good reason to include Master Chief, too. 

ODSTs

For Halo fans, Orbital Drop Shock Troopers are practically their own genre. The game Halo ODST added a jazz soundtrack and a moody, rainy city to the series’ oeuvre. ODSTs are regular people, not augmented to the degree the Spartans are, and free to bring their own histories and baggage instead of going through the homogenizing Spartan program as children. Using them would give the show an opportunity to add a squad of colorful characters hardened for military action.  Speaking of non-Spartan soldiers, the Halo timeline also includes a war between humans, which eventually saw the beginning of the UNSC military. This took place before the Spartan program began, though, which means it would be a stretch to see this era in a show that includes Master Chief. 

Halo 2 and the Sangheili 

Halo 2 let players take control of the Arbiter, the exiled alien warrior Thel ‘Vadamee. An alien-focused Halo story would be relatively expensive, so it seems unlikely that the show would focus solely on the Sangheili. But the Elites would make interesting subjects. They have their own politics and crises, a theocracy crumbling and making way for warlords and peacemakers. The Kilo-Five book series involved inter-clan Sangheili politics and provides a lot of lore that could be used in a television show. 

Spartan-IVs 

The newest generation of Spartans is made up of volunteers. Often career soldiers, they don’t have the traumatic childhood training of previous generations or the unmatchable strength of second-generation Spartans like Master Chief. The fact that they are recruited as adults could invite more storylines about past histories and relationships. And while most of Master Chief’s adventures with the IVs are shown in the games, the show could potentially carve out some time in which he served as a mentor to new super soldiers. 

Fireteam Crimson

Part of a relatively short-lived game mode, the Fireteam Crimson saga is a unique example of Halo 4 using gameplay to tell a story that doesn’t quite fit into the main plot. The fireteam starred in the cooperative Spartan Ops, a mode that explained some of the events between Halo 4 and Halo 5. The fireteam itself is a loose shell for the player or team of players, so there’s plenty of room for television writers to establish personalities and relationships for them. Spartan Ops also introduced another canon team, Fireteam Majestic, which gives fans another look at Spartan-IVs.

Fireteam Osiris 

Speaking of IVs, the most famous group is Osiris, the team hunting Master Chief in Halo 5. Their story was a main focus of the game but didn’t feel entirely complete. You can find more to their story in the live-action movie Nightfall and books like Hunters in the Dark. Team leader Jameson Locke once seemed to be in the running to be the franchise’s next major character, but Halo 5’s lukewarm reception might have removed that chance. If Microsoft wanted to bring him back, including Locke would be a good way to connect the television show with the latest major game. 

Onyx 

One of the keystones of the current expanded universe is the Forerunner planet Onyx. After various adventures involving the secrets of the planet’s nature and construction, the area has been colonized by humans as a remarkably mundane place with many amenities, including a high school. The television show could draw from the novel Legacy of Onyx, one of the most amusing and unique Halo novels in the recent crop, to tell a story of humans living and working on the bones of an ancient alien civilization ripe for another war story. 

The Created War 

The biggest question in the series right now is what will happen to Cortana. Her reveal as the aggressive and ruthless AI at the head of the Created movement was a big shock at the end of Halo 5, and one that alienated many fans. Will Cortana stay evil for long, or will the television show writers read the room and avoid digging a deeper hole for her to fall into? So far, the books and comics have touched on the actions of the Created a little bit, but mostly steered clear of Cortana herself. Could the show reveal more about her and what the galaxy’s AI plan to do? 

Halo Infinite 

The Halo television show could be a vehicle for Halo Infinite, the game that will continue the story of Halo 5. The trailer for Infinite shows an unexplored Halo ring—likely to be Installation 07, one of the last Halo rings and one which Master Chief deactivated. This unexplored Halo ring is perhaps the most marketable possible setting for the television show since it would act as a large flashing sign pointing at Halo Infinite, but it’s also not a bad choice when it comes to being able to tell new stories. Installation 07’s ancient ruins and alien animals could make for beautiful environments, and the untouched ruins give plenty of reason for characters to be there, especially if something goes wrong. Perhaps the show could end where Halo Infinite begins.