I couldn't wait, so I streamed up to day 18! All were AWESOME!
Day 8 wouldn't load in the Madvent; had to manually open it from its folder.
Day 16 is missing entirely.
Day 16 will need to be patched in, visiting its house counts it played so you can still reach the ending.
Also, is Day 18 supposed to be completely blank?
Yep! That was an anonymous entry. More info may come out later, hopefully, because it's dope.
Oh that is SO cool