(sorry my bad english.)
I’m makin’ a horror game, and i need a random jumpscare script, can anyone help me?
Learn about trigger colliders and instantiation and you can write your own.
The suggestion from Lethn is one good practical example of a technical method that could be used. But I would suggest that you will need a certain something more than just that. People aren’t going to jump merely because some pixels on a screen change.
How are you going to concentrate the player’s focus to the point that this change of pixels is going to actually shock them in the first place? You will need to engage with the player’s psyche - there is no simple script for that. 