"You've survived State of Decay. Now it's time to move forward and tell your own story. Take on an endless campaign with twists and turns based entirely on your own choices. Build up your score in the face of an ever-escalating zombie threat, and compete with survivors around the world. Complete challenges to unlock new heroes with unique weapons and skills. The deeper you go, the tougher it gets, and every choice is yours."
Breakdown is State of Decay's first DLC, which was released on both Steam and XBLA, on 29th November 2013. It adds a new game mode, Breakdown, featuring new melee weapons, firearms, playable characters, and being an infinite sandbox mode, in which one could play the game (in theory) forever.