Hmm, I think we made the game before the Switch Pro controller existed? We do know xbox pads and ps4 pads work though. You can either use WASD or arrow keys if that helps?
Ah, you don't have a QWERTY keyboard then? For a more complicated solution :D ... you could have your player 2 on another computer and use Parsec to play with them online.
Parsec site: https://parsecgaming.com/