Completed. But don’t know why the key works, as I could not reach it.
A little clue for the key: you can carry objects from previous rooms (pick up with left click).
Although I'm curious, how did you complete the game without the key?
I got stuck in the key room for a while and thought maybe I missed some controls, so I mashed the the keyboard keys one by one.
When it’s around the F~J keys, the door opened. Maybe I hit the debug mode key, because the safe has been opened too, though I can’t reproduce it.
