Makes me think of similar old flash games. :) I pesonally wouldn't do a multiplayer game for a jam, but I respect those who do. The art style was simple and clean, maybe the kings could have had something to set them apart from the blocks a bit more but that's nitpicking.
Some stuff needed exploration/just trying them out to figure out, so I think there could have been more visual communication. like it's not immediately obvious what the red balls do and how they differ from the basic ones.











