Cannot speak for Steam Deck, but now in July '23, pretty much all games work with Proton out of the box, (with between -10% and 15% performance loss) unless the

Cannot speak for Steam Deck, but now in July '23, pretty much all games work with Proton out of the box, (with between -10% and 15% performance loss) unless the game maker purposefully made the game unplayable on Linux (some AAA titles anti cheats for example). And then, as a Linux user, you can just return any game you like, past the return window, by marking 'doesn't work on my system ' in the return wizard. Sad thing that often the games that have the 15% performance hit are the ones most demanding of your hardware. It's also wierd playing some games on Linux, because clicking both left and right mouse button causes a middle click.