Hideo Kojima pretty much knocked it out the park with PT. While meant to be a teaser for Silent Hills, which is sadly never coming, many do claim that game to be the scariest of all time. At the very least, most would argue that the game was a brilliantly executed gameplay idea.
However, don't expect Hideo Kojima to go back into horror. Speaking to IGN recently, the designer said that he doesn't want to make another horror game for a pretty simple reason, he scares easily.
I get scared very easily. Actually, this is true of Alfred Hitchcock as well as Steven Spielberg. Because they scare easily, because I scare easily, it's actually easy for us to make something that is scary, because we understand what is scary. But while in that process, we're constantly imagining, like, terrifying situations so it ends up giving me bad dreams. That's the reason why I don't want to make a horror game.
And you know? That's fair enough. No one wants bad dreams. I do hope one day he changes his mind though as he clearly has a knack for it.