I want to do a thing where we each post to a story in a large group interacting with each other

example: "Hey yo gat how was your day?" then five or less minutes later(depends on what we are doing of course) "It was fine jim!"

Im thinking of making it on google docs, Its up to you guys. I want to have a fantasy adventure starting with weak characters in a group who set out on an adventure. Anyone can join or leave anytime.(kill or introduce yourself) I want to predetermine the story but not the dialogue or just where we are going and doing.
I do not want op character in this until later on. I want every one to start off weak and grow together.
The ooc section will be structured to give the story and what will happen like say someone suggest an enemy raid thats what we will do after deciding together.
The IC will contain dialogue and story elements

example:
post one "name: hey timmy"
post two "timmy gets hit by a branch and dies."(predetermined in ooc)
post three " name: NOOOOO


SO for the story I want a group of younger individuals going on a journey to after there town was wiped out by a war. They decide to join the side that didn't attack them and are sent on a mission to retrieve a stone kept in a mountain a couple of COUNTRIES AWAY.

This story can be changed so don't worry.