K, so, while the Hikikomori theory has probably been exhausted beyond all belief, I wanted to try expanding it more. Cuz' a big problem I have with a lot of theories is that they don't include much of the game play in their reasoning. Why would one part have some kind of symbolic meaning but all the other parts are just there? So I think the hikikomori theory can tie everything together very well.
If Madotsuki *is* a hikikomori, she's clearly afraid to go outside. Everything of interest in the dream world takes place outside of her room. So I think that everything you see in the game, collectively, is what she thinks the outside world is like, and is therefor something negative that keeps her from wanting to go outside in the real world.(In a semi-figurative sense.) She only goes outside in her dream world because she knows that she can pinch herself and return home risk-free. One important distinction from many "real" hikikomoris is that she seems to be very bored in her room. She doesn't have a computer, her TV is broken, I think it can be assumed that she's been through all the books on her shelf, and her only video game she owns is obviously extremely tedious and uninteresting. Dreaming is the only think she can think of to do.
The Toriningen are personally my biggest interest. I think they represent a fear she has of other girls. With their "fashionable" hair styles and clothing, and their gaunt figures and peculiar faces, they're like an exaggerated view of what Madotsuki could see as "popular" girls. She either sees them as ignoring her and not caring about her (Such as when they're having a party, which Madotsuki can't join in on.) or coming after her to violently corner her, always with a creepy smile on their faces.
Poniko could represent her fear of social interaction, as while she appears to be Madotsuki's age and a possible friend of hers, she ignores Madotsuki. When Madotsuki does something seemingly harmless by just touching the lightswitch, everything in the room changes to a demented alternate form that Madotsuki sees as a threat. (Or maybe Madotsuki is just afraid of the dark.)
I strongly agree with someone else's theory that the eyes prominent throughout the game are relating to paranoia, that Madotsuki feels like whenever she's outside, someone will be watching and judging her.
Mars-San is a fear of being homeless. The people on the train could be a fear of strangers. Perhaps Face really is aPost too long. Click here to view the full text.