This was a well polished game and I found myself playing it a few times to try and get higher levels. I liked the way it started out super-simple and gradually got harder. Agree with fog that a "last level" would have been good to skip the easy levels.
Some things it needed was some different sounds based on the icons used, some background music, and perhaps a tone or beep to signal the countdown if you got under 10. I found the final countdown a little distracting too, but it makes you more nervous and clicking furiously to try and win, so it does the job!
Was this supposed to be the solution to prevent a Bomb from exploding? A neat idea, for sure.
This is going in my voting pile.
I'm not a real programmer but I play one with DBPro!