Awesome concept, I am digging the style. I do have a few thoughts:
•Even on easy the difficulty is quite unforgiving, as someone else said I think it shouldn't require such precision.
•I believe there should be some kind of indication you have a ball in your hand, I know the main levels only give you the one but in practice mode there is no way to tell until you're ready to shoot. In addition to an audio/visual cue when picking one up, there should be a HUD element or some other constant visual indicating you have one.
•How about for the easier difficulty you include more than one shot? Give the player one of those refillable basketball crates or a limited amount, like 3 balls a level or something.
•The small bounds as someone else stated should be increased, I had a lot of trouble getting to the hoop in the level with just the one plane and one hoop on a building far off in front of it. Being able to swing more and come in from a high point would make it easier.
I do appreciate being able to restart quickly with a button press.
Also, do you plan to add controller support? My xbox one controller didn't do much besides walk/strafe. I wonder if a game like this would translate well when you need such precision to grapple, unless you accommodate for the joystick being less precise.
My 5 year old tried a little too, in practice mode. He was having a great time.