I saw this game on another site.
The rules are simple…
You can only post 5 words at a time, you can make the story go in any direction, for example I say “Once upon a time there” the next person can say anything that they want after that, for example someone could say “was a little boy who” and then it would be another persons turn to keep it going.
Try (as much as possible) to make your addition to the story go along with what the person above you posted.
Also don’t just have a conversation using 5 words, if there is currently a conversation put your part of the story above what you have to say.