Nothing compares to the sheer nightmare fuel that is the Silent Hill series, but since you're asking about the last game the disturbed me I'm going with Halo (the first game, feel free to laugh).
I was casually strolling through the level after the Flood, without any teammates, and my ammo had run out completely. I look at the radar thing (that shows any enemies around) and see nothing. So I continue running through a tight corridor, feeling uneasy as hell. It just felt like something was wrong. You know that feeling when you just know that something is off? The constant eerie sounds didn't help either.
So I look at the radar again - nothing. I finally get to a dead end and decided to turn around. As soon as my camera turned the whole goddamn screen showed a creature from the Flood, staring at me, gurgling. He was just sitting there, admiring me... Cue me jumping on the ceiling. I still have no idea why nothing showed on that radar, or why I heard no sound even through he had been following me for so long... Brr, I felt so stalked after that part...
I was casually strolling through the level after the Flood, without any teammates, and my ammo had run out completely. I look at the radar thing (that shows any enemies around) and see nothing. So I continue running through a tight corridor, feeling uneasy as hell. It just felt like something was wrong. You know that feeling when you just know that something is off? The constant eerie sounds didn't help either.
So I look at the radar again - nothing. I finally get to a dead end and decided to turn around. As soon as my camera turned the whole goddamn screen showed a creature from the Flood, staring at me, gurgling. He was just sitting there, admiring me... Cue me jumping on the ceiling. I still have no idea why nothing showed on that radar, or why I heard no sound even through he had been following me for so long... Brr, I felt so stalked after that part...