Overture
When the guy gets dragged to the hole. For my bad luck, I watched some playthroughs of Overture before playing, because I was so eager to play it. I even knew about that moment and I still couldn't go on. I ragequitted, after couple days I tried again...
The story. Come on, the story was creepy as hell. I especially liked the note where couple men were trapped in one of the shafts and the start how the man's empty look was described. Creepy. I was fearing for same kind of monsters from Black Plague.
I played Overture twice. Never tried to speedrun it, I did speedrun Black Plague couple of times. But, on the second try, I was on the part where you put the stick on the mechanism and open the door. For my bad luck, I never got that door scare on the first try. I went really close to the door and BAM BAM! JESUS CHRIST! Still haunts me...
Black Plague
Kennel all the way. The corpse, the notes. Mother of god... I played Black Plague couple of times, tried to find all the collectables on the kennel. For my bad luck AGAIN, I never got the dog scare, so when I got it. I just... couldn't go on. It was too much. Somehow I managed to continue...
The door pounding, 'Help me', the breathing at the messhall's little room. Little things like that.
I wonder why nobody added this or I haven't read that much... The room where the meltedface corpse was. The pressure to just pull the switch fast and GO! The music made it 50% creepier. I couldn't... It was so much. I knew it would just pop up and come to alive. But, it didn't... I was disappointed.
After Overture, spiders seemed little and didn't really scare me at all.
Requiem
All the infected sounds. Very little things. The story partly... I wasn't disappointed. I really liked that style of gameplay. Puzzles. Reminds me of Portal a little bit.
The most scariest was probably the sewer part. I don't know what that was, but it felt like there was some kind of big fish... I was so scared to swim in the water.
Another one was where the burn thingy was, where you can only get by the ladder. I remember hearing infected sounds there. I was so scared to go back up.