Away to make this game more challenging is to make the world less saturated until the player visits / makes entrails a route thus bringing the colors back. But also making it that the player cannot take twice the same path. Thus ensuring it to be a more engaging game. Cause the ghost now acts as an extra layer of penalties, making the player think twice about avoiding them.
Overall I must say that it might be a fun game. I have played a pretty while though, in its current state as of 8th Nove 19