Love the idea behind it, the animations, and the sounds, but would suggest if you come back to it that you tackle the balancing. Was easy for me to begin filling up the board with the first level Ents, and got to a point where the enemy weren't making it onto the board. Maybe make it to the enemy doesn't start taking damage until they're visible.
Other than that though, loved the game Java! And hope you're feel better soon, if you're not already!