Do someone know what to do with this room ?

It's in the village from the beginning.
Edit: I found the solution alone, I didn't notice an hidden poster, during a perspective rotation.
There is a code embedded in the posters on the wall.

Spoiler:
The numbered tetromino posters around the room correspond to the code's order.
E.g., above, #1 is ↑ and #5 is →.
The code is:
↑ RT ← A → LT ↓ RT