I remember when this first came out, I had some friends over and we livestreamed our playthrough in VR. We had 2 streams going - one a webcam on us outside IRL, and another of the view from inside the rift, what the person in VR was actually seeing.
So we're getting through the slow build up, and haven't really reached the Alien yet. One of my friends was playing and he's walking in this hallway after escaping some of the androids, and he sees a stream of something coming down from one of the vents. So he says outloud "What is that?" and walks under the stream and looks up, only to see the alien sitting in a vent like Sam Fischer staring down, hissing and screaming. He lets out a loud "OH FUCK" and turns to run away, only for him to get immediately pinned, turned around, and the alien stabs his face to death.
It was AWESOME because it was the most cliched movie death ever. Everyone always thinks they'd be smarter than the dumb crew in situations like this, but my friend played out the death to a T.
There was another moment, not that far later on, when I was hiding from the alien in the medical bay. I was behind a desk, so I couldn't see him. I'm actually down on the ground IRL, peeking out through a crack under the desk. I'm wearing a transducer vest so I can actually feel the alien walking around the ship. I'm sitting, being as quiet as possible, when I can feel the alien walk from the left side of the room to the right side. I mean, I actually feel it in my chest, I can feel his location. I feel him stop directly in front of the desk. I can see his feet under the desk. I look up, and his head is above me, peeking around but he doesn't look down. I am trapped under the desk, and I can feel the thing hissing.
I knew in the bottom of my heart that I was safe, that none of it was real. But, IRL, my hair stood on end on my arms, my feet got clammy, my palms started to sweat. I vocalized all this happening outloud for the benefit of the people watching the stream. Eventually he slinked away and I was able to make my escape.
AMAZING game.