Very fun...
... and addicting. I found my self playing this over and over again. I like the idea of achievemnts aswell. The thing wrong with it was it needed more levels. For instance, I could play Bloons for a VERY long time because of all it's levels, And with this, once I completed it felt as if it had lost it's novelty. (although that was cured with a small break from it.)
I suggest making:
Player level design
More levels
Keep up the great games!