Well this game is certainly challenging. A smoother difficulty curve would probably be beneficial, as well as better onboarding as to what each tower does. That said, I was able to eventually gather what the towers did, but the enemies appear too quickly and too randomly, while my towers are pretty slow to place and to act. This could be amended with some better visual feedback and maybe some hotkeys to make selecting and placing towers faster.
That aside, the idea for the game was pretty good. The pixel art, and overall style, was also well crafted for a game jam. Good work.