Add me to the list of people who aren't sure how to collect the balls. I pressed every key I could think of, and also tried to goomba stomp them, but I consistently failed. I also accidentally ascended to Cube Heaven by mashing the space button during my attempts and stacking jumps so high I don't think I managed to fall back to earth before the time limit was up. However, I did enjoy chasing the balls, and if there was more feedback on the controls I think this could be a fun little game.