1. Open Game Killer ( I used the latest version )
2. Open game
3. Go to Zombie Mode
4. Turn off wifi without closing or using multi tasking capabilities of your phone. Or you can manually turn of your router.
5. Start a game, earn some gold.
6. Search until you have Below 10 results.
7. Keep on editing the found results.
8. Continue playing in Zombie Mode and earn gold and poof, gold hacked.