The "Next Level!" button stopped working on this screen. I hope I'm right in assuming it's the final level.
That was alright! The mechanics and art are competent, and setting up walls of towers is always fun. The health also being a currency is an intriguing idea.
While it's great (and much appreciated) that the sound effects don't stack endlessly, some of the sounds are prone to being clipped awkwardly. Maybe a couple of the sounds can stack if they're not playing at the exact same time? I'm not sure of the best solution to that.
All-in-all, good work! Congratulations on the submission!