1.6.4 has now been released.

Teeceezy

1.6.4 Live

The update has now been released to the App Store and Google Play store. It will remain optional for a short time so that players with automatic updates switched on can get it without a major maintenance break.

Update 1.6.4 fixes the exploit discovered with the latest update. There was also a bug that allowed a certain guild to gain stars outside of a challenge week. This has now been fixed and the stars gained have been brought back down.

The new challenge event will start only after all players have updated to the new build. You can find more info about the new challenge schedule and other improvements here: http://forums.nextgames.com/walkingdead/discussion/3679/new-challenge-schedule

Edit: If you are having trouble accessing the update (Android especially), go to www.getnomansland.com on your device.