Counter-Strike Nexon

It all started with the escalating conflict between terrorists who fought against wealth & inequality, and counter-terrorists who were trying to reduce military expenditures. The United States launched the 'Super Soldier Project' in an attempt to create an entity beyond human limits, capable of wiping out the terrorists. Despite his fevered efforts, Dr. Rex, an obsessed researcher who worked day and night on his theories and was also a leading authority on biomechanical engineering, ended up falling short of expectations.
When all seemed lost, an anonymous letter reached Dr. Rex. It included a report of a 'walking corpse' in Europe. The report, complete with location details, left Dr. Rex blinded by possibilities and, with no reason to wait, he immediately dispatched a team of researchers to the town of Heorgen to investigate and obtain specimens for his study.
In the early 20th century, rumors began to circulate around an abandoned warehouse where a secret religious group was set to worship witches and fire. Local leaders took advantage of this rumor to ruthlessly hunt and slaughter the 'heretics' for their own prestige and power.
Seemingly out of resentment for the living, the slaughtered corpses released a foul odor containing an unknown virus which used the bodies of the dead - their hosts - to spread, attacking and multiplying to create other new hosts. This is the reason why the European Union ultimately sealed off the area and kept it under strict control.
Regardless of right and wrong, Dr. Rex's team managed to sneak the virus away in a secret research facility where he continued his work. Unaware of the side effects, he successfully created the 'Rex Virus'.
After experimenting on multiple test subjects, he believed he had finally created Super Soldiers. That is until everyone started noticing a strange behavior related to the subjects.
They would gradually lose their minds and attack the researchers around them, a behavior similar to what would only be described as a... zombie.