One of the advantages of modern day consoles is the ability to buy and preload your games before release. In theory, this means you'll be able to play your purchase the moment its available in your region (usually midnight of release day). But in practice, it rarely works out as it should, as is the case with Halo 5: Guardians. The highly anticipated Xbox One exclusive sci-fi shooter is out on October 27 and developer 343 Industries has already stated that there's a mammoth day one patch of 9GB. This is in addition to the 46.19GB download of the game itself.
(Also see: Halo 5: Guardians Multiplayer Beta Preview - a New Hope?)
And it doesn't stop here, apparently some preloads may be corrupted if you aren't using the Xbox One's Instant On power mode. What this means is you'll have to delete your installation of the game and re-download everything again. This is as per developer 343 Industries' page which reads:
"We know you're excited to finally get your hands on Halo 5: Guardians on October 27, and we wanted to make sure you're ready to jump in right away. If you've digitally pre-ordered Halo 5: Guardians on your Xbox One before September 21 and are NOT using Instant On power mode, you may still have an incorrect "stub file" for the title, which is simply a placeholder file. Players that have this particular version of the stub file will be required to delete it, and reinstall the title."
(Also see: Halo 5, Forza 6, Rise of the Tomb Raider Are the Most Expensive Xbox One Games on Pre-Order)
The post continues, stating that if you pre-ordered on or after September 21 you can download the necessary updates when available, meaning you don't have to delete your install. To check if you have the right version of Halo 5, check if the file size is less than 40GB. If so, you will need to delete the file and download the game again.