As soon as I saw the description, I knew I needed to nerd out in the comments.
The theorized reason for the Uncanny Valley effect, and the one that makes the most sense, is death. When a human dies, the skin gets paler, loses its shine and "healthy" look, as well as a glassy-ness coming over the eyes.
All of this works hand in hand to fill all the boxes to the uncanny valley effect. The reason the effect exists is because corpses carry diseases, so we evolved to be disturbed by them.
Anyways, this game looks amazing! I can't wait to play it right after I comment this.