Most of your Halo: The Master Chief Collection save data will automatically transfer between Xbox, Windows Store, and Steam versions. There are a few exceptions:
- Mid-mission checkpoints in the campaign and in playlists do not transfer between the Xbox and Windows Store versions.
- Data on Steam for mid-mission checkpoints is self-contained and does not interact with Xbox or Windows Store saves.
- Fully completing missions transfers completion progress between all versions.
- Playlists that are partially completed do not transfer between Steam and Xbox versions.
- Customization and PlayerID unlocks stay available everywhere through the Xbox Live profile but might need to be re-equipped on a new platform.
For a full visual breakdown of what data is retained and when, check the chart below.