It's like this. Bungie have been releasing games without the intended plots for as long as there have been plots. The Halo 1 plot had nothing to do with the cortana letters. There was a huge, huge debacle here 10 years ago over Halo 2's plot. From reveals and previews, it was supposed to be the battle of earth. It turned out that there were 2 levels on earth, a bullet sponge final boss and the ending was atrocious. Bungie absolutely disgraced themselves by showing gameplay at e3 that could not possibly run on the hardware. In Halo reach, bungie showed a reveal trailer where Nobel team fly off to the battle of reach already taking place. Remember running around emu farms in the retail release? Absolutely absurd. Bungie abused their position to poison the chalice of the halo story by releasing a game that fundamentally and deliberately wrecked canon. As for the grimoire? H3's real plot was in the terminals. ODST's real plot was in the audio logs. Reaches real plot was in the data pads. Bungie game plots don't go in the games.