The Serum

Zack is a biochemical student, Have a research with Prof. Rudolf on cell "B", It produces antibody againts antigen. The objectives of their research is to make human will not die because of diseases. One day Prof. Rudolf is gone, and Zack try to find him, He got some clues from the incoming call from Prof. Rudolf office, Zack find that place, the door was unlocked, but alot of Zombie there, and Zack start to kill his first Zombie... so on...

Mode Survival :
Zack start to addict by killing Zombie,,
efficient technique, Head Shot and Brain Shot.
High Score for The Real Zack....