Bravo, I've got so much time for this kind of technical tomfoolery!
A few feature requests that I'm 100% not prepared to pay for:
* Commentary mode upon hitting the ball: Offers words of encouragement in inspiration mode or lots of expletives in troll mode
* Countdown beeps so you don't need to look to see when a projectile is coming at you
* Primitive turn by turn directions to get the projectile receiver in the optimum landing zone. E.g "Back a bit", "to the side a bit", "tuts back a bit more"