Good programming
More people should care about size. Not just on Newgrounds, programmers in general have become sloppy.
The game is very basic but fun. The only thing that bugged me was that sometimes the first few bars appear at locations where you can't get to them in time. You could make the first bar always appear in the middle, then randomise the rest. Oh, and it could use some sound, though that would be difficult to script :)