Write small story for game server

I have a minecraft server and I need a little backstory for the world. The server works like this, when a new player joins they are sent to a random location where they have to survive. Later in the game they are going to likely find other people and become friends and or enemies, irregardless the goal is they will work together and build towns and giant nations that can then go to war with each other. I need a reason or a short story as to why there in the situation they are in. Maybe it's a zombie thing and all the towns are gone, I don't know, this is where you will come into play.