Wow congrats on making a multiplayer game in such a short time ^^'
I could only test it with myself, but it's a pretty nice concept! I'd argue the controls were a lot too slippery for me, and also the fact that your input to switch gravity is based on the "normal" gravity makes it hard to do a quick and intuitive change mid-action, at least for me! (Also maybe it's because I was playing with myself, I didn't see the health bar of the "other" player go down as shooting them.)
Must be fun with a lot of player going around in all directions!