Great for puzzles and thinking .Have some real good levels where earning all 3 stars will be very tough and you'll need to spend exp points very wisely to complete those. Also it has a great feature of using exp points with flexibility as it can be changed or edited any time. So overall, a nice tower defense game to spend some times and for brainstorming. And one thing I would love the developers to consider is that it will be much fun to have some sort of archive for the monsters that appear and also some achievements maybe.