This is cool! I like tower defense games, and really enjoyed the day/night twist. I would encourage you to diversify the gameplay: different towers, different enemies, different levels. As it is, I found it really easy, and not much strategy to explore.
I liked the tower animations, and the unfolding of the terrain at the beginning. And like I said, the night/day idea I find brilliant (maybe you can also expand on that).
Little suggestions: smaller health bars and smaller laser size (imho).
Well done!
