@Larsiusprime: You never mentioned it was a demo. You didn't even give us hint of it. So if you had done so in the descriptions that maybe would have helped those people, me included, that got slightly if not really disappointed.
Well, what can I say. The game was nice and I enjoyed it while it lasted. But I agree with Danaban here. The fact that you have to pay to actually finish the game it's a "no go" for me personally. There such other great TD-games like which are totally free and let you play till you're too tired to keep playing.