This game is really impressive for a 72hr game jam! I guess I haven't looked through all the submissions, but I don't think I saw any other tower defense games. I liked you gameplay and take on the theme. I think sounds would have been nice, but I can also understand not having time in just 3-days. One other random thing to think about is that red-green colorblindness is the most common type of colorblind. There might be some people who have trouble differentiating your enemy path from the grass. Not really a big deal and did not effect my rating, just throwing it out there.