I just saw your edit, I'm glad you gave it a second chance !
Mirror looking more like a glass than a mirror is a feedback I got from several people, so it's definitely something I'll check, I need to understand how to make a good mirror, and good graphics in general considering this is the main flaw of my game.
The levers opening the gate was also something misunderstood, and I concluded it was because of a lack of direct link between them (like cables starting from the metal door and going to the levers). Also, several people didn't get the large gray rectangle at the beginning was a gate, it's still part of the graphics being lacking.
Anyway, thanks you for taking the time of playing and reviewing the game a second time !