On every modern browser I've used, it's no longer possible to drag the mouse cursor outside of the game and affect the orientation and power, which means to even complete most levels you have to use the Newgrounds Player, a Windows exclusive program. However, even if you use NG Player, if you close the window, none of your progress will be saved. This sucks since when I pressed restart while it tried to show a fail screen the game crashed. I completed ~75% of all levels with minimum shots before this happened. To have a reasonable shot at completing it, I'm guessing I'll have to use Internet Explorer. No one wants to use IE.
Edit: well, I've done it now using IE. It took a little while, and I had to tape a piece of paper on which I wrote onto my screen to consistently shoot difficult shots perfectly.