Thanks for playing! I'm glad you had fun. The controls are definitely crammed for four people on one keyboard, but the rules of the jam required it to be an option. My keyboard doesn't have a numpad, so I couldn't add those keys. Maybe I'll add the 'insert/home etc' block, though.
You can use any number of controllers, too, but only on the Windows build for some reason.
Thanks for pointing out the audio duplicating problem. Restarting the game was a hurried last-minute addition, so I'll look into that.
Cheers!