It has been 50 years since the apocalypse had started. Generation 2 was born. While you and your friends were at school. A group of scientists took blood samples of the students. 3 students, including you, had a rare blood type that can cure the zombie apocalypse. The other two students have already been killed for their blood. You and couple of trusted people had fled your shelter and went out into the zombie infested areas. It has been a 2 years since then and you and others have adapted to your new lives inside the area