It's a Secret Achievement - Agony UNRATED
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Published on ● Video Link: https://www.youtube.com/watch?v=9tD9Dq0CVpk
To unlock this achievement you need to find the secret room hidden just after the Ishtar Chamber.
You can find a full Agony Unrated achievement guide here:
https://steamcommunity.com/sharedfiles/filedetails/?id=2200134367