The concept for this game is very nice.
When I beat it, I didn't really feel like I earned it. This is because it told me that I won at a seemingly random point in time and the game felt a bit easy.
I feel like you didn't need to have a money feature; once you get a nice setup, you never need any more money for turrets and you gain money so fast, you never have to worry about it.
I feel like the music didn't fit the game, and I wish there where some sound effects.
The colours are too bright and don't fit together well. I feel like if you lower their saturation and value, and mess around with their hue, the game will look way better.
I think this is a cool game. You should expand on it.