Tried playing the game with a PDP Afterglow generic Xbox controller, but it just automatically scrolls through all the options as though the left stick is held down non-stop. Had to kill the game to return to my desktop environment. Only playable through mouse and keyboard, but this game is quite difficult to play in that manner lol.

I have this exact same controller and exact same problem (also running Linux, OpenSuSE 15.6 if that matters). The selected item in the main menu continually scrolls upwards without me doing anything. I can halt the autoscrolling by pushing the left stick down as far as it will go (and then quit the game normally if I stop it on the "exit" button), but that's obviously not an ideal solution.

EDIT: running the Windows version of the game under Wine doesn't have this problem.