Feels very strongly inspired by "Monsters are Coming!" and I respect it. There does feel to be a little imbalance between how often you level, how many buildings there are, and how often some recurring upgrades show up.
Otherwise; I enjoyed this quite a bit! I did notice that the castle upgrade building (not the masonry) doesn't do anything after the first purchase. It would be nice to have an offensive option be native to the caretaker even in a small amount.
I very much hope to see this pop up on Steam in the future! Great job!