You are the first person - that we know of - that has noticed the raindrops on the in-game menus; very keen eyes!
But we also adore this thorough review, you clearly have taken the time to explore around in the game. As devs there is no better rewards than players that clearly have given a game a lot of thought, so thank you!
Besides that, we are glad you enjoyed the mini demo! We've been working away on the full demo, so hopefully it lives up to what you've seen so far.