I really enjoyed this game. I think I figured things out pretty quick (got to the epilogue on my first try), but this game could definitely benefit from a tutorial for the player to realize what they're doing and how things work. I wanted to spend time to look at the tooltips for the shop, but there was a constant pressure from the knight, so I didn't want to waste time and let him get closer to do that. I really like the art style, and you incorporated the theme well. Overall, a very solid game.
Edit: One other thing I will say is that the tooltips can be intrusive and a little obnoxious. It would be nice if there was some other kind of indicator for damage being done to the knight or the windmill.