Kingdom Rush Origins

Kingdom Rush Origins does a lot right, but it’s also got one major flaw that sours the experience. The gameplay is really slow overall; there are frequent moments where you’ll just be staring at the screen for extended periods of time, waiting for the enemies to waddle their way across the screen. It’s only until you get to the later waves of enemies that the flow of gameplay starts to pick up a bit.

This one's for fans of the game already, which may be why $6.99 character IAP in a paid game is available, because people care enough to shell out for it. I guess I can't really fault that, even if I'm not entirely comfortable with it.