The art in this game is stunning! I also love the concept. It flips the whole gameplay loop of a tower defense game on its head. I think you could have done a little more with it, though - the trees could have been more interesting, and it might be cool if you could place some more interesting things to corral the enemies than just walls. There weren't many tactical decisions to make. I also found that the trees occasionally spawned too far away to reach the enemies, and my walls had to be used elsewhere - maybe touch up how the trees are spawned. Overall, an excellent interpretation of the theme!