Uh oh, that's not good!
If you want to share some details about what's going wrong I can (hopefully) help troubleshoot. The project's very bare-bones, so it doesn't do much to help you out when getting it initially set up.
It looks like there's a problem with the default p2 controls (specifically, 'C' and 'Special' inputs don't work). I'll take a look at that when I have the chance.
By default, player 2 controls are:
Customizing the P2 controls by selecting "Remap P2 Input" works for me without issue, though. I don't know if you've tried that or not, but please give it a try if you're still interested in playing - you can rebind controls to a controller or keyboard as you like. Any input rebinding you do will be saved in local storage, so you shouldn't have to rebind again unless you want to change up controls again in the future.