Welp since I got no friends I only could judge this game by running around on my own...
That being said, well done on making a multiplayer game on a gamejam, I am already impressed just by that.
Two things I'd suggest to improve
1 - the physics, it is good how fast-paced it makes the game, but it also made precise jumps impossible. F.e. try going into bottom-left corner on the map and try jumping onto that 2x2 square next to you. I fail to do it 8 times out of 10. It would be much better if slight tap on a jump button / one of arrow keys would change your speed only slightly, and not fling you all over the place.
2 - the way the main feature of this game is implemented. When I touch the ground the entire scene rotates to make your local gravity point downwards, completely disorienting players. What's even worse, after you lend, the keys you would use to switch the gravity field do not rotate accordingly, making it really confusing and forcing the player to manually keep track of the gravity at all times.