Fan of tower defense! The game is fun, the key using it a little confusing, I need to read the long controls in the description to figure out what is what. I would hope if there is a visualization for the range of the flower though, and some difference between each flower, but consider the time limit, I can understand that. I like the animation of the big flowers haha, very funny.
I especially like the idea that you need to collect the coins yourself, maybe consider you will get damaged by the enemy or your own bullet lol?
Is 20 level the final level? if so the game might be a little too easy haha. And maybe need to have a decent game-ending page to give player satisfaction of finishing a game.