As the alien Covenant invade Earth, the Master Chief must defend humanity's homeworld whilst discovering more about the rings called "Halo. Fixed an issue where the player who was not the host of a co-op campaign session would not earn progress or completion for a mission or playlist, which impacted achievements. The Heretic / Armory / Cairo Station The opening cutscene shows the two major plot threads that will progress through Halo 2: the fate of Master Chief, Sergeant Johnson, and the rest of the human forces, which includes Commander Miranda Keyes, the daughter of the late Captain Jacob Keyes, and Lord Hood, apparently a ranking official in UNSC and the fate of an unnamed gold Covenant Elite we Halo.
At the end of the game, just after an intense boss fight, Master Chief promises halo 2 ending :: Halo: The Master Chief Collection General Discussions.
Played through Halo CE and the back half in particular was such a slog because of the level design.