Ok this game is very cool and I'm supporting it!
Some advice's to improve it.
1- You can add a difficulty level like Easy, Normal, Hard maybe Extreme. The players that like the game at some point would like to start with another kind of difficulty, this I think it's important for the difficulty curve.
2- When playing in windows I choose the full screen option and to quit the game I had to press the windows button and then the arrow to leave the game. If you add the option to quit the game all players will be happy.
This is a nice game and I hope you're going to do some mobile version of it.
Cool pixel art simple and cartoon.
Nice job !