halo: reach
A prequel to the Halo games, Halo: Reach documents the fall of the titular planet in mid-2552 through the eyes of SPARTAN-B312, callsign "Noble 6" and the rest of his squad in their doomed defense of the world just prior to the events of Halo: Combat Evolved. The game takes a bleaker tone compared to the mainstrean Halo games and was notable for introducing single-player character customization.
This tag implicates halo_(series) (learn more).