If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Dr. zombie command thousands of zombies to attack angrybirds . Click to help the bird defeat Dr. zombies and zombie army now. Dr. zombies in each level will appear, with the improvement of the level, Dr. zombies will be more high-level, more and more crazy. But for Angry Birds , the rate of appearing invincible birds become higher!