N.O.『 Crystallis』

N.O.『 Crystallis』 is a prototype for a walking sim heavily based on mood, ambiance and personal meaning. 

In the game, you play as a child, apparently some kind of android left by former mankind, devastated by an unkown pathogen, named by extinct humans as "Chrystalis"

The game has some light puzzle moments but it is very much so a test for level and camera design.