It's an interesting idea but my main issue is that it is a bit hard to understand the gameplay and it is difficult to play.
I do understand that you didn't have enough time to implement everything you wanted to though, so I'm not trying to be nitpicky but say instead would could be improved in the future.
I think that the movement being having low acceleration made the game kinda difficult because I would stop to aim at an enemy and then slide away while slowing down and miss my shot. I feel like the movement could be snappier because there is already difficulty in moving around a ring as well as needing to line up your shot with the center.
Another thing that I didn't understand very well was the enemies. The enemies constantly move toward the player, so my first reaction was to dodge them and my second reaction was to shoot them. Dodging them doesn't work because they will just ram into the ring instead and hurt me, and shooting doesn't work because they don't die (Or maybe they have too much health to kill them before they reach). I think it's possible to keep them alive if I spin around them to keep them from hitting the rings edge but it doesn't feel like the intended gameplay.
Maybe to improve it, you could make the ring bigger and leave more space to react to enemies, and then make the enemies themselves easier to kill?