Some games from Steam can still be used without Steam’s DRM. It’s a little difficult to pull it off, but it can be done
A lot of games don’t require Steam’s DRM, you quit Steam and launch through the Steam directory and it still works. I haven’t tried it, but I’m pretty sure I can copy that game to a computer with no internet access and no Steam client and it’ll work. I haven’t done that though, I’ve only done it when I forgot my kids were playing on my account on another computer and wanted to play a game.
A lot of games don’t work this way, but a lot do. Try it for yourself.
You’d need something like the Goldberg Steam Emulator, since a lot of games rely on services and APIs that Steam provides