The upcoming Halo TV show doesn't exist in the same canon as the games and books, instead telling a whole new story taking place in what's being called the "Silver Timeline."
In an interview shared to Twitter (via Halopedia), 343 head of transmedia Kiki Wolfkill explains that creating a new timeline allows the TV series and games to be their best.
"We're referring to this as the Halo Silver Timeline as a way of differentiating it from core canon," Wolfkill said. "And both protecting core canon and protecting the television story, and by that I mean being able to give ourselves the chance to evolve both and for both to be what they need to be for their mediums without colliding with each other."
The Halo universe is a complex, at-times messy place, branching several games, books, comics, and an anime series - and they all exist in the same universe. To try to tie a TV show's into all of that would be a massive undertaking and could hinter the series' accessibility, so it's easy to understand the reasoning here.
In retrospect, Wolfkill might've been teasing this announcement in an earlier interview with IGN, where she said the Halo TV show would reveal a different side to Master Chief.
"The biggest challenge with adapting the game is, the game is designed to put you into [Master] Chief's armor. What we're asking people to do with the show is to sit back and say we're going to present a side of Chief that you just don't get to play in the game."
The Halo TV series is reportedly set for an early 2022 release on Paramount Plus.
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