Once I have to take my Win 7 off-line, I won't be able to play ANY Big Fish games on that machine because an internet connection would be required.
And Jenny100 said my games will all "become demos" without one
I'm not sure you understood me, Mad.
If you've installed a game on your hard drive and activated it with the Game Manager, the game will stay activated on that computer even if you uninstall it. Big Fish games that have been installed and activated do not suddenly become demos when the computer goes offline. It's only when you want to install a new game on that computer that you need to go online again.
If you've never installed and activated that particular Big Fish game on that computer, you'll need to install it and activate it at least once.
You can copy (not move) the game folder to an external drive, then uninstall the game using the Game Manager. Now you have a copy of the game on your external drive, and the game has been activated on that computer even though it's been uninstalled.
If you attach that external drive back to that same computer, and play from the external drive, the game will work as an activated game. Or you can copy the game folder back to the hard drive and the game will play from that location too. You may have to create a new Desktop shortcut for the game if you change the location of the folder.
If you attach that external drive to a computer where the game was never installed before and try to play the game, it will play as a demo.
The difference is whether the game was activated on the particular computer or not.
And I don't know if the setup game files I currently have stored on my large external drive would be "valid" on a Win 10 machine.
Backing up the setup files is practically worthless. All the tiny setup files do is start the Big Fish Game Manager, which automatically connects to Big Fish and downloads the game files from Big Fish's server over the Internet. The only advantage of backing up Big Fish game setup files is that if you have hundreds of them in your collection, you may be able to sort them so that they're easier to find than the way Big Fish sorts them.
If you back up anything, it should be the game folder. The game will work on any computer where the game has been activated, but will play as a demo if played on a computer where the game was never activated.