I really like to see some clever new mechanics introduced in tower defense game and this one was pretty neat. The mechanic of activating towers with a flashlight is something I haven't seen before anywhere and it is works really well for increasing strategic value in tower placement. My only complaint is that it takes some time to get the economy flowing as first money comes hard. Once you get it going it's a really neat tower defense game.
PS. Really love how you used assets to make big main castle.