I like the game idea alot. To be a mimic inspector is a awesome concept.
Personally I would use a different kind of mechanic instead of the Zebra Puzzle (i think that is how this is called):
I would the adventure inspect each part of the chest. Each part can possibly have some "strange" anormalies (e.g. tantacles on the back of the chest, or the lock is upside down). If you discover one it gets marked down into the magic notebook. If you die the notebook is passed to the next inspector (Meta Progression).
Like in Quarantine Zone: The Last Check but with mimics :)
Also the artstyle is really amazing 5/5!
One note: I first played it on 21:9 and it completly brock the UI, as i switched to 16:9 it worked fine.