It's def difficult to make puzzles in games that are difficult enough to be satisfying to solve but not too difficult to cuz players to quit, and that's def a skill that comes with more attempts at making those kinds of puzzles. I tried finding it on my own and after a while I was able to successfully find the code! It's an interesting game in terms of atmosphere that I think would have benefitted a lot from some horror audio. 

Also I really think you should look into making a WebGL build, it's very easy to do and is really accessible for players which will allow you to have more people play your game.  Here's a short and easy vid on how to implement it I really hope this is helpful!

Very cool concept with the spray but very confused game.  I don't find any digit for the door :/.

It's a good game, it has a few bugs, it would have been even better with some horror background music, I'm not sure, but maybe I was just blind and it was hard to find the code, but let's say a little help wouldn't have been bad.

Very cool game really liked it!

a very unique idea 

"I see a black wall and I want to paint it white" *sing* .... nice game^^ well done

Woaw ! Amazing experience with this game !! Very original, I love it !
Not easy to understand what you have to do sometimes, but I still managed to finish it, I'm happy!

I really like the mecanic and the various gameplay make this game awesome ! Good Job !!