This is incredible!
I'm ashamed to say I was expecting something much more generic than what I got. The writing's good, the worldbuilding is so efficient and woven into the main mystery, which is also excellently done. I'm sure other people saw the twists coming, but I was genuinely surprised several times! I don't think I played any other adventure game that packs this much goodness in such a tight 2 hour package. I love The Name of the Rose and Dune and whodunits, so in retrospect I shouldn't be surprised, but still!
2 minor complaints: When you're asking Tiabata about her “reasons”, choosing the “simple” option lets you see both options eventually, but choosing the “complex” option skips over the simple one (I did that my first time around). Having gone back and read both, I think “complex” first then “simple” would flow nicely and should be possible. Or better put, the fact that it isn't possible felt accidental.
The other one is a small bug (SPOILERS!!!): once you use the screwdriver 3 times, you can use it a 4th time on any of the loose screws and the game doesn't account for that. Ava says she'll do the 3 all in one go, then proceeds to say "That's already loose" 3 times. I realize I'm a dummy for trying that, but it still felt awkward haha
Anyway, congratulations again on an amazing game. I won't soon forget my time on the Nation!