Hey I tried this out!
I don't have an Xbox controller, so I couldn't really do much with the mouse. It does seem to work with selecting options and navigating the screens, but I don't know how to shoot or change weapons. The only other controls I could find was the jump. Also are we supposed to be shooting the other player? Because I don't see an avatar for them, or any guns at all for that matter... Just a crosshair target in the middle of both screens. (I did end up downloading because I thought it was just a browser issue)
Feel free to try my game out as well, I could use your input: https://wasabiiii.itch.io/grass-elemental-demo-demo
If you have some solutions please get back to me on this!