I have been toying about with my steam folders.
I have currently got both Linux and windows on seperate Machines, I have them on both Laptops and Desktops.
I have copied my entire Steam folder over from my main Windows PC ( This had all games fully up to date ) and I copied it to my Linux PC too, and I knew that it would need to download some binaries etc, but surel;y a vast majority of the data files should be 100% identical surely?
The Linux PC still had to downlaod a huge amount if files, but it did save a great deal too!
Then, with the Windows files all up to date and then the Lunux files up to date, what I have done, is copied the Linx files onto another HD. that I setup as NTFS, then under Linux, I setup that NTFS Drive as a game location.
This let me see how Linux would load its games off an NTFS drive... It did and it was not much different in speed to an EXT4FS Partition
Ok, so with that extra drive, I then installed a Dual Booting PC, I put Windows 10 Pro and Mint 18.3 KDE ( Both 64 Bit Versions ) and I fully updated both with the latest updates and the current drivers, I installed Steam and updated it on Windows then on Linux, and then I added the Hard Disk that I copied the files onto ealier and then I added the installation location in both Windows and Linux and while it did work, it seemed to keep wanting to do loads and loads of updating all the time.
I might be that it wipes over some Windows files when I am in Linux and Linux Files when I am iun Windows... This may not be the case for all game,s but it certainly does seem to be in a permanent state of updating.
Perhaps I need to give it more time, but I was playing jus ta couple of games. WarHammer SoulStorm is one that plays under the new PROTON thingy and thats updating all the time, and there are a few games that did not seem to show up and so they obviously dont need to be updated.
So, the fun kind of stopped as I have a KVM and multiple machines and so dual booting is a waste of time for me.