How to Move a Steam Game to Another Drive, The Easy Way
Steam offers multiple library folders, and you can choose where you want to install games when you download them. And you can easily move a game after you’ve downloaded it without re-downloading the entire thing.
This process can save you from downloading tens or even hundreds of gigabytes of game data all over again, just because you got a new SSD and want to move a few games. It’s different from moving an entire Steam library folder, which moves every single game inside it — the following process will let you move only a few games rather than the whole library.
I have a small 128GB SSD drive just for booting Windows 10 for the two or three Windows only Steam Games I have that will not run under a VM on Linux. I'm going to try this, and move all my "Windows only" based games to an NTFS partition on a separate drive, and then see if Steam on both Windows installs will see that one "external" libraries folder. This will mean having only two Steam games folders to backup, one Linux folder and one Windows folder. Any re-installs of my OSs will mean not having to restore GBs of Steam game files.