Well done on making a game, it was actually surprisingly well balanced, something on which other games in this genre often fell short. One flaw that is persistent in these kinds of games is that you just keep spamming troops. I also could see the darkness counter in the first level (it was behind a tower), which really confused me, would've swapped the coin and darkness counter (after all the towers use coins while we use darkness.
Overall I'd say, although unpolished, this is actually a really charming game, great work!