At first I didn't know how to play. I thought I was supposed to put the ball in the net but didn't know the controls and how to play. Luckily I found out. I like the game, basic but for a game made in 4h it's pretty good. =)
The game is pretty simple and me personally I didn't have trouble with the hitboxes. And I think the ball could use linear interpolation (smoothing).
(Message for new players, use LR arrow keys to make the ball climb up)