I'm not a fan of tower defense games, but this one had some interesting ideas (liked it when a cannon destroyed a spot). Not sure how this could be done, but I think it should be more obvious what's every enemy's weaknesses. Maybe a mouse interface could make the game feel nicer and more intuitive (I had to recall which button did what every time). Nice sprite work and setting.
Check our game! https://cerosware.itch.io/one-stick-shooter