Halo: Combat Evolved storyboards
From Halopedia, the Halo wiki
During the development of Halo: Combat Evolved, the game's script and story went through several revisions. These storyboards are various early editions and interpretations of the game's story, and are displayed below. These storyboards were created by Lee R. Wilson and were published online on Bungie.net and ArtStation.
In early 2001, Lee R. Wilson was hired to work on the storyboards. Where he was  By at least April 9, 2001 Lee had finished X10 page 4 as noted by it being shown on the Bungie Webcam on that date.
This is the start of the The Pillar of Autumn level.
This happens during the The Pillar of Autumn level.
This is the end of the The Pillar of Autumn level.
This cutscene was cut completely but presumably happens after the The Truth and Reconciliation level during the escape on the Spirit dropship.
This happens during the 343 Guilty Spark level and is the Flood reveal.
This happens during the start of the Two Betrayals level.
This is cutscenes split throughout The Maw level.