Very fun game, though I think there should be a ramping price for miners since you can get exponential growth of money by spamming miners. At some point in the game, you can end by spamming the exploding ticks because of your cash flow. Either that, or perhaps the AI of the knight should begin to prioritize miners at some point. It's still fun when you have a ton of money, since it's funny to watch the knight get swamped by imps.
Either way, it's a real fun game, love the art as well.