I like this game very much, specially catching those zombies ..... Thanks DECA games for such a wonderful GAmE ........ but ..... InCREASE the Time of Challenges and from 1 hour to 4 Hour or MoRE .......... because, due to high amount of time(s) those drones take to find zombies, makes it IMPOSSiBLE to finish Challenges in 1 hour .......... and don't say use Plutonium to find zombie faster as plutoniums are Very Hard to get even for SMaLL upgrades ........ THANKS......