Instead of the current control scheme, with the awkward cue, I think you could try something like this: 1, No cue. 2, Clicking on a ball and holding the mouse button down displays an aim circle. 2a, Moving the mouse at this point aims the shot. 2b, A speed bar goes up and down during this process. 3, On mouse release, the ball moves off in the direction you chose with the speed on the speed bar at the moment of release.
Fun game! What about giving the player unlimited bags and one-way doors and leaving it up to the players to figure out the most efficient solution on each level? It's true that it would let people fake their way to the end, but on the other hand it would add an extra level of challenge for veteran players. Just an idea, you probably already thought about it.
This game is really fun and addictive. My only gripe is that the five untimed heads at the beginning get boring because it's still important to optimize them if you're going for a high score.
 "Depict1"){kind=icon}
 "Continuity"){kind=icon}
 "Typing Asteroids II"){kind=icon}
 "Marble Challenge"){kind=icon}
 "Talesworth Adventure Ep. 1"){kind=icon}
 "Noggins"){kind=icon}