One of the joys of Halo is its replayability. Ask any devotee and you’ll get some story about endlessly rerunning “The Library” in Halo: Combat Evolved, or replaying Halo 2’s “Delta Halo” to get out of bounds and explore that uncannily Canada-looking mountain range. Sadly, at least at launch, you can’t do any of that…
Source: Kotaku – You Can’t Replay Campaign Missions In Halo Infinite