Pretty cool concept and great sound design with a lot of room to grow; one thing i would've like was a proper tennis scoring system (love, 15, 30, 40, the whole deuce thing, etc.), maybe limit when you can affect the ball to certain times (like when it is being hit back to you) (or maybe you could pivot to like saying wind is pushing the ball left or right, and then have the player use it and the wait for it to recharge); for a full game you could easily create a bracket with harder and harder ai as you go up