This is great! Really enjoyable, really clear, and not buggy. Excellent work. I enjoyed the music, the steady pace, and the nice graphics/effects.
I did not like my fire rate, but I understand I could upgrade it. I think the fire rate would be a lot more manageable with a reload indicator, so I knew exactly when I could fire next, instead of spamming LMB. Another thing is that using LMB to interact with buttons and towers is fine, but it does sometimes spend my ammo. With the low fire rate, an unintentional shot is pretty frustrating.
Aside from those 2 small tweaks, I really liked this one. Great work.