This is a cool idea, but there doesn't seem to be much choice on the player's part, unless I'm misunderstanding the game. I just bought as many skeletons as I was allowed to on each day and watched them fight.
Also, it seems like your sprites are using bilinear filtering which makes them look super blurry. I'm not too familiar with godot but there should be someway to disable bilinear filtering, this will make your pixel art look wayyyy better!!