Interesting game, I liked the twist on the tower defense genre. The art and the lighting all looked really good.
If you wanted to improve, I suggest some form of in-game tutorial. It took me way to long to figure out how to play and how to focus the light. I also suggest having some form of count down timer doing, somewhere it was mentioned I had to survive 5 minutes but never knew how much more I had to go.
Overall really fun game!