Updated: 2020-10-02
I play most of these games on a Linux system, without a desktop environment, usually a tiling window manager.
Scratches: Director's Cut
This is an older, first person point and click adventure game, in a big house. An Argentinian game, certainly one of the best adventure games out there if you are interested in a horror-mystery type of game. The devs new game will be Asylum, which will have native Linux support.
Any problems: Luckily I recently made it run. At first it complains about not being in full screen mode, but then the intro starts and everything is fine. Sounds, music works, and I didn't need to do any tweaks in-game. It's not in full screen because the game doesn't support higher resolution.
I also disabled any overlays, since the game doesn't have achievements, I felt it is not needed, and usually it can cause problems. Changing workspaces is working, which is good for looking at walkthrough if you get stuck.
Unfortunately this game is not on sale anymore, and according to the old dev, it's in a legal limbo currently.
Proton version: 5.0-9