Warning! Spoilers ahead for Halo episode 1.
While Master Chief may have already removed his helmet in Halo's premiere episode, he's only rarely done so before, and there's a good reason his face was never revealed in the games. The Halo TV show made it clear from its trailers that its Master Chief would be showing his face in the series, and its first episode delivered on that promise. This marks the most significant reveal of Master Chief's face in Halo's history, as while the games have occasionally allowed the character to remove his helmet, his face has only rarely been glimpsed.
However, the very first episode of Halo saw Pablo Schrieber's Master Chief remove his helmet and reveal his face in full. After fighting back against Covenant forces who have attacked a colony on the world of Madrigal, Master Chief and a team of UNSC Spartans are able to secure the powerful artifact the Covenant were trying to obtain. Contact with the artifact restores some of Master Chief's erased memories, prompting him to defy his orders by sparing the life of Kwan Ha, the lone survivor of Madrigal.
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This development saw Master Chief remove his helmet in order to gain Kwan's trust, and his face remained exposed for a significant portion of Halo's first episode. The reveal of Master Chief's face marks a slight departure from the way the character was handled in the video games, in which he rarely removed his helmet, and his face was only ever briefly glimpsed. However, the TV show breaking tradition doesn't take away from the story as the reasons behind the story choice differ from the video games. The reason the Halo games never showed Master Chief's face in full was not necessarily
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