I sleep so much on such design aspects that I didn't even think of the select SFX, it's probably the default one! Thank you so much for bringing it to my attention!
I was unsure on where to put the interface for most of development, so feedback on that is also very welcome. I'll probably try some more positions and eventually ask around where it feels more natural to players, as by myself I'd really just leave it where it is. There is an option to fill in what other resolutions the game can be in, but I did completely forget to fill it in.
Your feedback really is a bunch of things I'm numb on and do need the help with, thank you so much for being thorough on analyzing the UI and UX.
(The Spiral gimmick is completely Junji Ito inspired, so if you suspected that you're absolutely right.)