From their website:
After the Horsemen allows you to explore the world after it ends. All Things Zombie told us the story of the catastrophic events that “ended the world”. The Zombie outbreak and subsequent failure of the Lazarus Project brought the world to its knees.
Governments fell, economies collapsed, but the world didn’t end. Man survived and small pockets of survivors carry on rebuilding the world but this time in their image.
But everyone has a different point of view including those that are more or less human…