So I've been tinkering around since I saw this about an hour ago... I have a 8bitdo Zero 2 controller I carry around with me and since I'm at the office it's all I got atm. I've discovered that you can indeed use a controller with this, but you'll need to manually set it up in Steam. Add the exe to Steam as a non Steam app, and then edit your controls so that (if using the Nintendo layout, as most 8bitdo controllers do) set it so that A = D and B = S as keyboard commands. W and A can be set to X or Y, and make sure you manually set the D Pad correctly. I think I've got it working now.