Few rules that I recommend:
Play in a group of 3.
Avoid playing this alone, because its way funnier in a group.
Don't use physgun.
Don't run, walk (walk = dont hold shift down).
Stick together (If you have a group)

Notes:
I have not proberly tested this one.
I rushed the end part.
Is not so scary.
Is short.

Made by Emnu, alias Hannu Korvala