How do I preserve my save data
I recently got a hankering to play the game again. I've forgotten a fair amount of the game mechanics, and wanted to run through the first bit of the game again. However, my last game is about 66% of the way through, and I don't want to lose that progress. How do I preserve my prior data such that I can get back to it after playing the beginning again?
The default location of the saved game state for the Steam edition is in:
C:\Program Files (x86)\Steam\userdata[user ID]\241930\remote\gamedata.sav`
That is assuming you installed Steam in the default location. The bold part is the ID of the game.
I haven't tried this myself, but I think you can copy that current file as a backup (a simple Ctrl+C and Ctrl+V to copy into the same folder and let Windows rename the file), and start a new game.
I would have liked to verify this first, but, as you likely know, these games are notoriously ginormous.
Alternatively, I can suggest to just pick up the game where you left. It's an open-world game, dying is nothing more than annoying, so there is plenty of freedom to reacquaint yourself with its mechanics. I just did the same with Shadow of War, after at least six months of not playing, and got into it again very quickly