Ehhhmmm. Maybe?

It kind of depends on the game. If you need to download a native version, then something must be downloaded. If you're playing with proton, you shouldn't need to download the whole game.

However, Steam may decide that it knows better and still want to download the whole thing again. Sometimes this can be changed by cancelling the download and doing a verify so it will only download what it needs. This may also shorted the download for native games, but again depends highly on the game.

Give it a try and see how it goes.

If you're on Steam you can save your games to restore them without downloading the whole game again.
For your windows only game it may be better to restore them in Linux and download just the proton part.

If I remember correctly, the restore option can be used when you change the steamplay option.
Ex you save the game installed with steamplay (windows installation ) and you restore without Steamplay (Linux installation). You will need to download a fraction of the game.

Why not dual booting just to see if you can "copy paste" a game from Windows to Linux ?

Stick to windoze.

you will feel the pain. u will eventually go back to windows get some headeache and will come back again linux
meanwhile you will be learning the linux.
Finally u will become Linux user. Then u will feel the strenght. which comes from your past pains.

Yes, it's possible with Steam, but you need to do it carefully.
1) find saves and back them up
2) on Linux, install Steam, make a new library on the disk you're gonna use, do not reuse the old library
3) install the smallest windows game you have into that library using Steam play
4) carefully move the files excluding saves after you get the idea about the folder structure, where to put manifest file and where to put the main game folder
5) restart Steam so it can see your games
6) run each game once and Steam will create a proton prefix for each game in a separate folder in that library, the name for prefix folder is an ID of the game
7) you can now copy your saves into each prefix folder, it mimics the windows disc C:\ structure

Quoting: Kuduzkehpanyou will feel the pain. u will eventually go back to windows get some headeache and will come back again

In my experience, any curious individual who has wanted to try linux but values games over freedom and autonomy will, 100% of the time without fail, always end up running back into the clutches of Windows.

Quoting: GuestI’m the

purveyor of the worst windoze practices among the unsuspecting Linux neophytes. Ergo an enemy of everything we stand for.

Ah, but thankfully you'll get tired of the rubbish you peddle sooner rather than later. Maybe you'll even get a life!

Yeah, you can install Linux into your OS hard drive. You can even do it and keep Windows. That way you can pick which OS to use when you bit up. I found dual booting to be very helpful for the first few years.

Sadly, your other hard drive with the games installed, probably won't work. There's a few technical reasons, but basically Linux and Windows are binary incompatible. They can't run the others programs.

There is a way around this. WINE and it's fork, proton (which is maintained by Valve as a part of Steam) lets Linux read and execute windows programs. But doesn't work all the time. Some games will work with no issue. Some won't load at all. You can check wine's appdb and proton's protondb for your games to see if they even work. Especially do it for your favorites!!

Either way, I'd recommend installing Linux as a dual boot and giving it a try. I game as a hobby and there are certainly games I own that don't work and games that I won't buy b/c they won't work. It's disappointing, but know going in that all your games might not work.

My main reason to go to Linux was the cost. $0 forever is very compelling, especially when I can take the 100$s I've saved over the years and buy more Linux games. There's enough out there I don't really miss the games I can't play.