My method in getting the hard badge: Follow the setup of SirVoltsworth (thank you bro!) and when fighting avoid open spaces and walk straight line besides the wall that can divide/prolong the upcoming group of zombies. Secure spaces that can be used as a retreat (like clearing one direction then just go wipe the rest after securing your location). Reload as much as you can. Try to charge towards the normal zombies cuz they are the weak spot in the barrage of zombies. and I use keyboard and mouse and auto aim :)
oi manuelotto your game here is bad but in facebook its good because here it doesn't load thats why everyone gives crap to you not like XD no offense just stick run fan .. facebook version ..
 "Reaper of the Undead"){kind=icon}
 "Stick Run"){kind=icon}