I would have liked a keyboard key for the attack, instead of having to have one hand on the keyboard and one on the mouse. That's just my preference though, nothing wrong with mice! If you were to do more with it, it could use more variety in the enemies and more variety in the upgrades. Maybe some way to go to other lilly pads?
Nice-looking art. Simple and clear goal, I didn't notice any bugs (other than the flies). I got all the upgrades, it kept my attention. 🙂