A pretty simple concept that is executed quite well! there are some balancing issues that you’ve already noted but I think if you were to resolve them post-jam like making units cost some form of currency and not being able to just mass spam them, having units and towers have some form of stronger synergy in terms of strategy and having the unit upgrades be more impactful the game could be really fun to play.
There wasn’t any music as far as I could tell so adding some of that would be a nice bonus!
The art-style is pretty cute :]