All in-game achievement progress vanished between the time I played this last night and just now. The levels I unlocked were still unlocked, though. That aside, fun game!
Alright... first, the ? button explains most of the game. The "ghost balls" at the top are how many shots you can make that don't form a match before a new wave of balls is added. The counter on top ends the game when the count reaches 100. That's understandable. Now the bad. The game does not end until the count reaches over 100 *AND* the balls settle in the middle. This means so long as you keep shooting and popping balls, the game never ends, but it also means your screen will fill with balls. I have a screenshot of my game where the ball count rolled over after hitting 1000. Also, that guideline seems to appear at random. This game needs some bug fixes, serious bug fixes.
You'll get it!