I actually got it running in this "white screen" mode, and finished it, the sprites were somewhat changed, the protagonist one the most, but otherwise finished a game and had great time playing it.
Also, I think the 6123 puzzle is somewhat hard to understand, needed to seek for the answer in the internet, I think something like "But the west door is already opened, I need the reverse is this" or something similar would help, but that's just my opinion
Good luck in the future!