

Resolution defaults to 1920x1080 which is too large for the Screen, but most of the screen is still visible. Resolution can be chaged to 1366 x 768, but with some difficulty.
Game starts out at a too large resolution, which can be corrected in the Options Menu. However, selecting 1366 x 768 can be a struggle since the game recognizes the Steam Deck inputs properly, but using the D-Pad to move up and down had a strange reaction causing the game to select and deselect the Resolution option. Further more, the option you need is outside the area the mouse can access. It took some "fiddling" with the D-Pad, Mouse, and A Button to be able to select the Resolution option then go to the Right to select the off screen 1366 x 768 which made the rest of the screen visible.
However, once this headache is done with, the game plays on Steam Deck as intended on PC with an X-Input Controller.

(GOG version) Works well
Played GOG version with Proton 7.0-1.

Runs perfectly.
I originally decided to run this in Proton because the native version has some strange context-sensitive controller issues with my wireless Xbox 360 controllers. Running it in Proton fixes this issue.