So, everyone by now has played Halo: Reach. And, by playing Halo: Reach on September 14th, 2010 you will know that, that day will live in infamy. Yes, yes, your first response will be, but the multiplayer was good! Firefight, forge, and online multiplayer are all worthy additions to the Halo multiplayer aresonal. While those multiplayer modes may be fun, the canon of Halo: The Fall of Reach was ruined in the video game.
To begin the battle of Reach, as outlined in the novel, stretched from August 30th to September 1st 2552. The game offers a glaring deviation from the original time-span of the battle. The game states that the battle begins when an advanced Covenant strike force arrives on July 24th 2552. So why did the UNSC not know that the Covenant had discovered the location of Reach and initiate the Cole protocol. Because in the game, Reach falls on August 30th. The clear answer to this question is that Bungie did not properly think out their own canon and completely disregarded the canon, outlined in the novel.
In the game a Covenant super-carrier breached Reach's orbital defense grid. And, this was no, ordinary super-carrier, but a "cloaked" super-carrier. If the Covenant had cloaked super-carrier technology at their disposal, they why not simply use that technology during the Battle of Earth, during the events of Halo 2 and Halo 3. It seems the Covenant could have spared many loss of lives during the battle of Earth by simply cloaking their super-carriers and slipping below the orbital defense grid, as they did during Reach.
Not only does this violate game canon, but common sense. The next, glaring, plot-hole in Halo: Reach is the issue of Cortana and the Pillar of Autumn. I will adress the former and then the latter. The Fall of Reach (novel) clearly states that Cortana was given to Master Chief (Spartan 117) who tested the AI on August 28th. During the game Cortana is given to Noble-6. This is after she said that she choose Noble-6. In the book it clearly states that Cortana chooses Spartan 117 to be her custodian and keeper. The game clearly deviates from the book by showing that Cortana choose an inferior Spartan III model over a Spartan II model.
In addition, the game also gives the Pillar of Autumn, a different back story. In the Fall of Reach it is stated that the Pillar of Autumn was refitted in orbit, in the Reach shipyards. Not on the ground, in drydock as the game shows. During Halo 1 it is even stated that the Pillar of Autumn is not rated for atmospheric flight, so how did the Autumn fly in Reach's atmosphere or did Bungie violate book canon and Halo 1 canon? In addition the novel explains how Master Chief got on the ship and the original mission of the Spartan II company, on board the ship. The game however states that the ship has been at dry dock all month, did not participate during the space battle of Reach, and makes no mention of how the Master Chief got on board.
Not only did Bungie deviate from canon established in Halo 1 and the Fall of Reach, but created huge plot-holes. Halo: Reach could have been an excellent story that showed a differnt aspect of the battle of Reach, but Bungie decided to completely disregard all existing canon and orchastrate major retcons. Halo: Reach will go down in Halo history as a botch canon job that created more questions than answers.