Fatal Frame 4, easily.
I legit had to sleep with the light on one night after playing it.
Just creeping down corridors, feeling watched, and never knowing when a deadly phantom might appear through a wall or materialise right behind you, gets the adrenaline pumping. The main antagonist, an invincible not-quite-ghost, can show up at any time, forcing you to run for your life. More than once I had to take a moment to gather my courage before going into an area where I'd recently seen her. Sound design really helps, with a chilling suite of heartbeats, moans, and ambient noises to curdle the blood.
It doesn't just rely on "terror" either. Some of the scariest scenes are the quiet ones, where you see a ghost enact his last few seconds of life, cowering and pleading in a dead end in an underground tunnel, where he and the last survivors of his island tried to hide from a being neither alive nor dead, who roamed the entire island killing at will, until its population of thousands was exterminated.
