That one part where we learn about the twist surrounding Mari's death, oh my God. I kept thinking "No way... nonononono" and I felt my stomach churning. But I also think that it's presented at first, in a very malicious way. At least, to me, it almost felt that Sunny had pushed her down the stairs on purpose and they were just covering it up. However, the way it's presented, is obviously the way Sunny/Omori remembers it. There's a lot of guilt about Mari's death and so he frames himself and Basil almost as cold-blooded killers.
Obviously, Basil's reaction to Mari's death in the stairs to frame it as a suicide is beyond fucked up and I guess that was his way of trying to protect Sunny and he's constantly taking the blame of this - in part, because he is to blame (since, I'm not sure if Sunny wanted to frame the whole thing as a suicide to begin with, my impression is that he didn't). It's weird, though, part of the photos of what happend to Mari (repressed memories of Sunny) show Sunny kinda smiling in one pic where they are moving the body. I feel that, again, it was just a distortion of his own mind/Omori, framing him as this killer more than just the accident that it was - or just trying to make it seem like Sunny was manipulating Basil all along. However, shouldn't Sunny and Basil still go to jail or something? The ending makes it seem like Sunny eventually tells his friends (his biggest fear finally overcome) and leaving with his Mom.
I really did like how the game portrayed trauma, both in Sunny and Basil. Sunny seems to have repressed everything, gone numb and completely isolated from everyone (thus, becoming a hikikimori). As for Basil, it feels as though he kept pretending to be okay but his fears/concerns kept manifesting in different ways (in what I guess was a breakdown by the end of the game).
Also, holy shit at that one last photo of Mari hanging from the tree with one eye open being a parallel to that thing following Omori around. I also really liked the parallels between "dream world" and real life world (and how everything was actually a lot harder to do in real world; lol eating candy in real world wouldn't heal shit haha).