

Setup menu would not display in default. 4.11-13 used to configure, then switched back to default.
Finished game in windowed mode
While in fullscreen, game would lock up after switching windows. Playing in windowed mode works around that.
Opening steam overlay locks up the game
Achievements unlocked fine for me
occasional screen tearing, not hugely annoying for this type of game
The native port does not support achievements, so you have to run the Windows version in Proton if you want them. The game crashes during the intro with Proton 5, but it works in 4.11-13.
(Note: as far as I can tell, save files are not cross-compatible between the Linux and Proton versions)

Play with Proton if you care about achievements
As with the first two games, achievements don't unlock in the native version. Playing with Proton works around this.