Feedback wanted: Some questions on Ending (spoilerish)

[hollowleviathan]

Got all three, plus the hidden one in the Prison Cell. Got that extra one by just trying to find a way out of the prison and due to boredom i triggered the prison cell ending. It was a cool thing.

Oh, no! The Prison was the most terrifying/confusing area for me, I squirm at the idea of going back for this secret. I vaguely recall a second more reclused iron gate that could also have been doused with acid, but it could be a fever dream.