I don't understand what the hype is all about when I read the comments. There is no puzzle, just standard check in and go to your room then there is that ending that feel like you lost but when you try again, you realise that this is really the end. It feels like the intro of a game.
For "lost hope" medal, What I did was take the bottle near the ghosts that drink tea, click on one specific of the many candle flames "a bit of a pixel hunt" then click two time on the painting near the musical sheet. I don't understand the logic, the name of the medal or how this is a puzzle but it worked for me.