After I earned eight badges I went to check if there is something interesting in all the buildings in Lumiose City. In one of the buildings on the Northern Boulevard (without a name), I went to the 2nd floor, and something really creepy happened.
The music stopped. The screen faded a few times. I was unable to move or do any actions. Then a Hex Maniac girl floated around me in absolute silence. She floated away at the end of scene, saying only...
I went around searching for the girl or any clue. I found nothing. It was a regular cubicle-office floor without people. 1st and 3rd floors have people doing their own stuff.
Is this some kind of developer joke, easter egg connected with Pokemon creepypasta, or is it something else?
I experienced this. Check it out if you dare :)