Amazing game! Hands down this should be the jam winner! I just have no words to describe how good this game is. This is indeed a demo for a full game and I'd love to see the post-jam progress! Instead of thirty paragraphs worth of praise (which your team certainly deserves) I will instead throw a few friendly nitpicks I found while playing (which will not change the rating!).
I feel like the player should be able to close the messages by clicking on them, instead of having to reach the keyboard to press space. Iirc this is the only thing which needed a keyboard button. Other than that everything could be controlled via mouse.
The player should be unable to start a wave when no towers are on the ground. I did that mistake once because I thought I could buy towers mid-wave, lol. Also speaking of waves, I'd love to see a final wave indicator! I didn't know which wave was going to be last so I wasn't sure if I should keep some funds around for further towers or I can spend everything now. Also, I'd love to be able to speed up the time!
Other than that, again, I bow down to your team for this amazing game! Can't wait to see what you can come up with in the future!