The developer has identified the issue, and released the following message on the official message board:
”First, I want to apologize. This is not acceptable, and you deserve better than this.
Second, we’re on the phone with our publisher right now getting everyone mobilized. There’s nothing we can do at UL to fix this problem. Once the update has been handed off, the process of getting it to you is something only the Xbox people can handle. So, we’re calling in the troops to get going on solving this problem immediately.
Third, although we can’t directly fix the problem, you are OUR players, and we’d like you to know we’re exploring ways to express our appreciation for your patience.
In the meantime, see “first.”
I wanted to let you know what was going on as soon as we had it nailed down. We don’t have an ETA on a solution (see “second”). Stay tuned for more information as we get it.”
State of Decay was released on the 5th June 2013 on Xbox 360.