"Remember the good times? Where you wouldn't move, and I wouldn't move, and nobody would try to eat each other?"
Slender: The Eight Pages spooked me good. Both in a Let's Play I made when I was 16 that's far too cringey to share, and just now when I booted it up to grab a screenshot.
You're in a wood. There are eight pages. There's a Slender Man. Go.
I doubt that premise survived being stretched across the numerous levels in its Steam successor, but for a one-off job it's perfect. You'll remember the main trick: looking at the monster will freeze it in its tracks, but stare for too long and it will eat you anyway. That leaves just one option, known as running the fuck away.
EXCEPT whenever you sprint you deplete your maximum stamina, so you're still running towards your doom. Your flashlight only has so much battery, too, so you'll want to turn that off when you don't need it. You always need it.
I got through that Let's Play through a combination of whimpering and improvising comforting songs about lichen. Good luck.