Technology

Old games are likely to work better, as new games are likely to use new features or behaviour which aren't yet handled properly by Wine/Proton.

Check protondb for reports on whether a specific (steam) game runs.

In my experience, pretty much everything that doesn't have anticheat works. I can't remember the last time a game didn't work fine, from stuff so old it stopped working in Windows Vista to day 1 AAA titles. Even DOS stuff is playable with DOSBox.

Just be aware, Linux is not windows. If you try to use it like windows, you will only experience pain. It's not hard, especially with mainstream distros like Ubuntu or Mint, but you really should invest at least a bit of effort into learning how the system works and how to use it properly.

As long as the game isn't a title thats using something bleeding edge, it will work day one. And as long as the game isn't using an non proton compatible anti-cheat, it should work. Unless said devs arbitrarily decided not to tick the "proton compatible" box cause of some hard-headed bullshit.

I would say old games work better also get Steamtinkerlaunch which makes fucking around easy

If the game isnt steam just add as non steam game and bang steam will handle the rest