Not much, very minor bugfixes (like the killer not being able to get into the electrical room after 20:00 and the killer's animation being frozen). Those bugs are all fixed and there are also some very minor visual changes that most people won't even notice anyway. :)
The entire game is littered with hints actually, if you just look carefully you'll see many hints that kind of point towards an ending/what to do.
If you really want help, try looking at the map. the map says something about "music?" with an arrow pointing towards an area and the music box says something about "all six fates". Now what could that possibly mean? The map also has some colours that point to where an important object might be.
Also try calling the communication center at different times, the floor of the com-center seems a bit...dirty, doesn't it?
That's all the hints I'm gonna give, remember to try out everything you can, it's more straight-forward than you think! Thanks for playing the game. :)