I like the idea that when something reaches the boundary of the field it moves to the opposite side. It adds some space for strategy. I would say you can turn even such a simple idea into a really enjoyable game by just adding some juice. Add more sound, visual effects, and some dynamic feedback from the game (for example knockback) and it will become 100 times better, However, I'd say it's good for your first project.. Good luck on your future path!