The premise of the story is good, it puts the pressure on the characters to put themselves in an uncomfortable situation right of the bat, which is clever. However this only works because the mother is very controlling and overprotective of her son. Clearly she has some issues from past relationship with the father and who knows what else.
Now, the BIG problem I have with this story is the "role-play persona delusion / memory loss" gimmick.
It instantly removes all the tension between the characters and removes any sense of progression between them. It reminds me of the cheap "mind control artifact" or "book of corruption" gimmick other similar games uses to either skip a sense of story progression, so you can just put in a sexual scene quicker, or to simply cover bad writing.
And to make things worse, it seems the mom fluctuates in and out of this at random. Going from her Persona and having no memory of anything to letting her son (which she now acknowledges as her son) fuck inbetween her thighs while she is lying naked on her bed like it was nothing. I'm not even gonna talk about the penetration scene and the schizo mental gymnastics that happened there.
The disconnect in the continuity of the story is too much to handle.
And meanwhile all of this we get no insight into what the mom is thinking, all we know is she might be suffering from the same mental illness that Leonard Shelby did from memento (great movie).
I could say a lot more about the writing in specific scenes, but I think I've made my point.
The mom is hot though, so there's that.