im usually one that will play at default difficulty in all games, and even hard/expert if i want an extra challenge, but between all the different aspects of the game it was just too much for me to handle. I honestly believe if they just made the zombies a bit easier to kill and leave everything else the same then default difficulty would have been perfect. i get why they did it but feel they went overboard. 3 headshots should be more than enough to down any vanilla zombie.