I have talked a lot about how games and science are heavily interconnected. I’ve covered the various studies focused on video games and gamers; as well as the way gamers help to make massive scientific breakthroughs. However, the link between science and gaming goes even deeper.

We have all heard of simulation games. Video games like The Sims, Elite Dangerous, Flight Simulator, and the Tycoon series all seek to model the real world as accurately as possible. Gaming companies pour their resources into research in order to reach this goal. Although, there have been a few instances where video games managed to mimic real life with an incredible amount of precision and accuracy completely on accident. The Corrupted Blood pandemic is easily the biggest example of when the virtual world comes surprisingly close to reality.

On September 13, 2005, Blizzard introduced patch 1.7. It included a new level 60, 20 man raid called Zul’Gurub. The final boss of the instance was the giant, winged serpent Hakkar the Soulflayer. Although the current level cap is over 100, achieving level 60 in 2005 was very prestigious. Needless to say, Hakkar was no pushover. During the raid players became infected with the debuff Corrupted Blood. Once infected, Corrupted Blood dealt anywhere between 875 to 1125 damage. It would then take another 200 hit points every two seconds for a total of ten seconds. Corrupted Blood could jump from avatar to avatar and hunters could pass the disease to their pets. For level 60 players, this was more of a nuisance than any real threat.

Corrupted Blood should have stayed within Hakkar’s domain. However, if an infected pet was dismissed before it was cured or died, it was put into stasis with the debuff still in place. Players would then transport to a nearby city and summon their pet again. From there, the virus spread like wildfire because Corrupted Blood had an extremely high transmission rate. Populated cities and transportation hubs were quickly overrun with the plague. Lower level characters died and skeletons littered the streets. Areas with high populations like cities, banks, auction houses, and farming locations became hot spots for the virus.

Players quickly started fleeing to remote areas. Except they only succeeded in spreading the virus even further. Blizzard attempted to create a quarantine zone to try and stop the virus from spreading to uninfected areas. However, they could not erect a complete barrier. Players who were suspicious of the quarantine refused to remain within the infected zones. It didn’t take long for Corrupted Blood to reach pandemic proportions. Four of the eleven servers were infected by the end of the first day.

A few players tried to help by healing and resurrecting infected avatars. Ironically, their interference only helped to increase the spread of the disease. Other players intentionally returned to Zul’Gurub to infect their characters and carry Corrupted Blood even further. It wasn’t unheard of for players with infected avatars to simply give up and try to take down as many poor suckers with them as they could.

The interesting thing about the Corrupted Blood pandemic was that players were emotionally attached to their avatars. They had spent a lot of time, effort, and money on their characters. So when the plague hit, players reacted similarly to victims of an actual viral outbreak. To top it off, in World of Warcraft the playerbase spanned a wide range of demographics and came from all walks of life. The Corrupted Blood incident quickly caught the eyes of epidemiologists who studied and published scientific papers on the subject. Ran Balicer compared it to the avian flu. Corrupted Blood also had parallels to the cholera, Spanish flu, and bubonic plague epidemics.

In World of Warcraft, players can instantly teleport from one location to another (often to large cities). This transportation ability helped to simulate a disease’s ability to travel long distances. The lower level players were very similar to vulnerable populations (i.e young children, the elderly, and the immunocompromised). A few players acted similarly to first responders and tried to help by healing or resurrecting infected avatars.

These virtual first responders, much like our first responders in real life, became infected with the virus. Normally, a virus that spreads that quickly and kills that fast would burn itself out because it rapidly runs out of hosts to infect. Instead, because there was no way to become immune to Corrupted Blood, the newly resurrected and healed characters would just fall ill again. Thus, the virus always had someplace to go. Other players intentionally returned to Zul’Gurub to infect their characters and carry Corrupted Blood even further. These destructive jerks, while obnoxious, actually helped to simulate those who continue to go to work or school despite an illness.

The high level NPCs stationed around the cities also assisted in spreading the disease. They became infected with Corrupted Blood and acted similar to asymptomatic carriers of a disease. Asymptomatic (without symptoms) individuals are unaware that they are ill and can easily transmit the disease to other people. Since the NPCs did not react to Corrupted Blood, it was impossible to tell which ones were carriers. Additionally, pets acted as another reservoir for the disease, making it that much harder to stop. Eventually, Blizzard had to perform a hard reset on the four infected servers to stop the spread of Corrupted Blood.

The reason why scientists were so interested in the Corrupted Blood pandemic was because of the wide demographic and the way players reacted. Human behavior, by its very nature, is impossible to predict. People don’t always react rationally and they will often make poor decisions in tense situations. Models just cannot predict the irrational and downright dumb decisions people can make. People can be too curious for their own good (i.e. journalists, researchers, and idiots). In the case of viral outbreaks, they’ll get closer than they should and wind up contracting the disease themselves. It happened during the Corrupted Blood incident and actually occurs during real epidemics.

Unfortunately, even World of Warcraft’s Corrupted Blood incident wasn’t a perfect model. The intentionally destructive behaviors of some players combined with Corrupted Blood’s high infection rate and game mechanics prevented it from being a perfect parallel. That and, you can’t just reset the planet every time there is an ebola outbreak. However, it does show that video games can become a tool to model epidemics and pandemics.

One of the biggest problems with epidemiology is that you can’t do experiments. Scientists are able perform observational and retrospective studies. However, you can’t really run around infecting entire regions with the bubonic plague just to see how people will react. In addition to that, models just are not accurate enough. Thankfully, the Corrupted Blood incident demonstrated that MMOs are a viable tool for research and experimentation. The only moral barrier to killing millions of virtual avatars is that a player’s consent in needed in order to use their data for science.

Thankfully, it wasn’t just science that has profited from Corrupted Blood. Blizzard used the incident as inspiration for the Scourge Plague/Zombie infestation during Wrath of the Lich King in 2008. In 2012 Bioware implemented the Rakghoul plague in Star Wars: The Old Republic. Not only did this plague mimic the Corrupted Blood incident (although this time it was on purpose), but the virtual virus did a better job at simulating a real disease.