If you're having trouble beating it on seriously hard, just start a new game on easy and fix the helicopter. This ending lets you bring 5 survivors to a new game, so you can start that new one on seriously hard with 5 really solid survivors to start out with
 "Rebuild 2"){kind=icon}
 "Waterfalls 3"){kind=icon}
 "Geometriax"){kind=icon}
 "Zombie Outbreak Simulator"){kind=icon}
 "Wake Up the Box"){kind=icon}
 "Take Something Literally"){kind=icon}
 "Smoking Kills"){kind=icon}
 "Empires"){kind=icon}