Great jam game, well executed visuals and sound effect. The gameplay concept is good but as you're targeting an eventual commercial release I'll give feedback with that perspective and considering this a prototype version:
1. Managing towers by manually moving the connector cable is a bit tedious, a button to do so would be smoother IMHO
2. The waves could come from more directions to increase variety
3. Music would add a lot to the experience
4. The game could be more intuitive so even skipping the tutorial makes the player able to pick up and play (point 1 above might help with that).