Your name is Isaac. You are a mercenary that has been hired by Logitech Inc. to go into one of their labs and take care of the situation there. You are there along with seven other mercenaries: Hank, Joe, Frank, Stone, Steve, Phil, and Josh. None of you want to know each other's last name. It is considered to be unprofessional in your business. The helicopter you are in lands on the rooftop of the lab and Mr. Langstrom, the guy who hired you approaches. Probably for a briefing.
"Alright, gentlemen," Langstrom says. "Your mission is to destroy a highly dangerous entity called the Reanimator. It was supposed to be a cure for every problem humanity ever had. It is a symbiotic organism that attaches itself to the host's brain and feeds on a portion of their blood and in return, it reanimates the dead cells within the body. We had one of those in our Subject Zero, but the Reanimator became violent. It wanted more blood but didn't want to risk killing its host, so it did something unexpected and caused a mutation. It made Subject Zero powerful enough to break out of his containment and go on a killing spree. He fed on everyone he found and everyone he fed on was contaminated with a Reanimator. So the corpses soon woke up and were under the control of a Reanimator as well. Roaming the halls, looking for meals."
"Did they mutate as well?" Steve asks.
"No. Subject Zero's Reanimator is the only that was put in a situation where his host was insufficient to meet its needs. It is the only one that has gone beyond humanity."
"What are the rules of engagement?" you ask.
"Shoot on sight. I recommend you never travel alone, and aim for the enemies' heads. It is useless to try to kill the hosts, you'll have to kill the Reanimators pulling their strings. Additionally, we kept a weapon in Subject Zero's cell that should destroy all Reanimators in the vicinity."
After the briefing, the door opens. You grab your gear and head out of the helicopter.