The zombies get hungrier and appear more the higher your score is from killing zombies. wasd to move, click to shoot 1 to switch to pistol, 2 to switch to machine gun things to watch out for: backstabber zombies - they come from behind and try to attack you unprovoked. speed demons - they run super fast and are really important to get rid of. Shielded Zombies - they have a strong shield that halves your damage except for the machine gun which is is hopeless against shielded zombies. There is occasionally a 'zombie burst' a hundred zombies spawn every once in a while to give the zombies an upper hand. To win the game you need to defeat the bosses. When facing the boss you get a special boost - the AK 47. press 3 to access the gun. damage is heavily boosted.
thx toathis aaaaaaaaaaaaaaaaaaaaaaa