Works out of the box, without tinkering
Game tends to crash if Steam Overlay is opened and left untouched for some time.
Just be cautious leaving Steam Overlay opened and untouched for long enough: game might crash. If you haven't been writing down the passwords, you might lose a big chunk of your progress.
Works with Proton GE 5.11
The game worked out of the box on my laptop running Lubuntu
On the other hand the game crashed before loading on my Desktop running MX 19
Didn't require any particular line options or setup, however the controller setup in-game didn't always map the controls properly unless Steam handles the controller options itself.
Unlike previous reports, no special configuration was needed -- it worked immediately. Played through the first stage and also adjusted various settings without apparent issue.
Working fine with this workaround: execute steam with PROTON_NO_ESYNC=1
Doesn't start. Oddly enough, running the executable with wine, works fine