Halo: The Fall of Reach is a 2015 3D animated military science fiction miniseries based on the novel of the same name. The series is produced by Sequence, a Vancouver- based animation studio. The miniseries was also made available as a bonus feature on Halo 5, but only on the limited editions of the game.
Halo: The Fall of Reach (miniseries) Wikipedia
The miniseries tells the origin story of the Spartans and their development as a military force and the beginning of their quest to fight the Covenant to repel the deadly alien invasions.