It's great that there is character movement and interaction with the environment. Good job for making the art yourself!
I did not manage to solve the puzzle - I did piece the torn pieces of paper together and got two different codes [SPOILER] "door 2303" and "8615". Both of them lead to releasing the monster and failing the game...Maybe I did not read the numbers correctly - they are not legible and because it's pixels it's even less clear.
In my experience this game has no story whatsoever.
Good luck with expanding it.