Okay, maybe I was expecting the game to do something different, as I was going from the controls in the game's launcher (Unity default stuff I guess?)
But still, after smearing my keyboard for a few minutes, I was only able to get the ball to move when I hit the C or spacebar, but usually only after the third key press.
The behavior of the ball is the same whether I tap it slowly, quickly, holding the keys down for different lengths of time; the ball makes a little hop on the third keypress, moves slowly upward, resets when it leaves the screen, then sits in the middle of the screen and doesn't respond to any input after that.
EDIT: If I hold down the C key while the ball resets, it will roll away after it drops.