Nice little game - A little feedback;
In games where you have to click a lot, it can get at bit annoying when click+hold=drag, Because you often end up with small movements/twitching of the screen/view when you don't mean too... Maybe make the movement be rightclick+hold=drag to eliminate unintentional movement.
Also - even though i like the font for the text in the game, it doesn't really work for the numbers. especially the 2 and 5 are really similar and "unclear", and almost both look like 8's.