Oh, I see now! I looked behind a few times but there was no one there, so I figured those were mine.
Viewing post in The Corner of Your Eye jam comments
The idea comes from a period of psychosis that I would often see a tall masked man out of the corner of my eye and when I looked it would turn out to be a plant, traffick cone, pole, etc. So you hear him behind you but when you look you can only catch a glimpse of him for 0.1-0.2 seconds before he disappears and is replaced by a prop. It's difficult to spot so I understand not everyone catches it but a few people I've watched play it live have had the reaction of "I keep feeling like I saw someone but I can't tell" which was ultimately the goal. Difficult mechanic to get perfect lol