If the game supports local co-op or LAN and you intend to use it, this bin is usually required. Online Fixes
It is helpful to see how other repack groups handle multiplayer data to fully appreciate the fg-optional-multiplayer-build.bin convention. fg-optional-multiplayer-build.bin
If you have downloaded a recent AAA game from a scene group or a repacker, you might have stared at this file wondering: Do I need this? Can I delete it? Why is it taking up 15 GB of my SSD? If the game supports local co-op or LAN