https://github.com/wesnoth/wesnoth

Wesnoth is one of those games where once you start playing, you fall into a time warp and lose hours before you know what happened.

Damn good bot!

I’m sure it will depend a bit on your exact setup (video card especially, and likely display server too) but I can confirm that Baldur’s Gate 2 (the only one I own on Steam) literally just worked with the built-in Proton emulation. I clicked install, then once it downloaded I clicked play and required no additional intervention.