I found that there have some changes in some places after you entering from the Circus Tent to the Big Doll or entering the crying doll head in the Doll World.
I had read some old post that said it was about "狂乱値" (madness point?): if you are lower than some point you will be allowed to enter or reach some places like the projectors in Train Station and Apartment, the isolated area in the Factory, the way to the flooded forest etc. When these points get higher those places will be blocked. The madness point also allows you to get the Aya's ED2 & ED3 in the old version.
I post this in the comment not in the guide because I still did't confirm how much point will cause how many things change (I don't know how to use RM2000), so I put this information here for more reference and discusion.