great game, i really enjoy playing it
you should add an option to use "guard" with one survivor on the other so he would follow him around and kill any zombies that come near him (helpful with fighter/scavanger combination)
another useful thing that could be added is something like an auction house that people could trade items with eachother for other items or fuel.
when you lose a game and return to the last save every ability that was previously full is empty, you should make it that it saves the position it was because it leaves us players at a huge disatvandage while playing