No matter where you are, there is a different kind of zombie. In the spawn cities, you will meet the weakest, in the interior, you will meet the somewhat stronger ones, and in military bases, you will encounter a multitude of die-hard undead. Some of them can keep sprinting forever, some wear armor, and some scream for reinforcements. In addition, since the update, you can better block hits from zombies and cause them damage to the head more easily.