Good game i had fun playing it this is the feedback i have for it.
1. the ai seem to just stand closest to the ball they can get on their side (I only played agist the easy ai btw) this is problematic because it makes kicking kind of useless and the best strategy is to just grab the ball and throw it over the ai's head which gets boring.
2. the arena is a little deep so if the ball gets kicked over to you side you just have to run all the way to the end to get it back. Mabey it could be shorter so people have to thing about what direction they kick the ball so it doesn't come bouncing back to their side.
(this is smth i thought would be cool to add) some pillars or smth to each side that bounce the ball so that you could do some cool things like kick it to a pillar then catch the ball and throw it somewhere to make it more interactive.