Corrupted Blood incident
While developers intended to keep the effects of the debuff within this boss's game region, a programming oversight soon led to an in-game pandemic throughout the fictional world of Azeroth.
Corrupted Blood soon spread beyond Zul'Gurub through players deactivating their infected animal companions, who when reactivated in densely populated non-combat zones, still carried the debuff, becoming disease vectors, while non-player characters became asymptomatic carriers.
After several failed hotfixes, Blizzard ended the pandemic by performing a hard reset, and a later patch prevented companions from contracting Corrupted Blood entirely.
Although it was the result of a software bug, the Corrupted Blood incident gained longstanding notoriety among World of Warcraft players and interest among real-world disease researchers.
Epidemiologists, meanwhile, took interest in how MMORPGs, unlike mathematical models, could capture individual human responses to disease outbreaks rather than generating assumptions about behavior.
[7] These pets were subsequently re-activated after the completion of the boss battle, but developers had forgotten to include an "off-switch" that would recognize the conclusion of the raid and remove the debuff from companions.
[10] Players who defeated Hakkar would subsequently fast travel to markets in urban centers in order to repair their damaged armor and weaponry.
"[2] Casual World of Warcraft players who had read about the incident on the news would log into their accounts to better understand the pandemic, promptly infecting their characters.
[7] The in-game environment soon filled with the skeletons and corpses of player characters who had succumbed to the infection, and internet forums described seeing "hundreds" of these bodies throughout Azeroth's population centers.
"[16] Some players incorrectly speculated that the Corrupted Blood incident had been intentional, with developers intending for the Hakkar boss battle to lead directly into a pandemic-based game event.
[10] Although the pandemic did not extend to the real world, epidemiologist Nina Fefferman noted that "players seemed to really feel they were at risk and took the threat of infection seriously, even though it was only a game.
[15] One griefer whose guild engaged in this practice told Wired that he did so because he was amused by the reactions of other players, saying, "It's just funny to watch people run away screaming".
[11] While the company quickly became aware that Corrupted Blood had spread beyond its intended reach, identifying and fixing the issue that led to the pandemic proved difficult.
[12] These outbreaks also came on a rolling basis: the plague would dissipate after running through a particular game region, only to re-emerge once players, believing that the danger had passed, repopulated the area.
[22] On October 22, shortly before the release of a World of Warcraft expansion set titled Wrath of the Lich King, several mysterious crates appeared in one Azeroth town.
[23] Blizzard put a stop to the Lich King plague on October 28 after receiving complaints from players that the zombie infection was detracting from other parts of the game.
[25] To limit griefing attacks, the 2020 Scourge invasion was designed to make opting into the event more of a conscious choice by players who wanted to fight against the zombie hordes.
[28] Unlike the Corrupted Blood incident, BioWare intentionally released the Rakghoul Plague, and player characters who succumbed to the disease received special items.
[29] Lead designer Daniel Erickson told reporters that the Rakghoul Plague was inspired by the Corrupted Blood incident, but that developers wanted to steer players away from griefing and towards positive interactions with the pandemic.
[1][32] Despite its accidental nature, the Corrupted Blood incident bore several resemblances to real-world pandemics, leading researchers to explore the event as a disease model.
[33] Of particular interest to researchers in the use of MMORPGs for epidemiology is that character responses to a virtual pandemic are the result of individual player reactions, adding "a level of authenticity that doesn't exist in other simulations".
[24] While the Corrupted Blood incident created a focus on video games as tools of disease research, there were some specific aspects of the debuff that limited its applicability to other pandemics.
For instance, the basic reproduction number of Corrupted Blood was significantly higher than any observed real-world pathogen, which in turn affected the rate of spread and player reactions.
[1] Lofgren compared the in-game "first responders", many of whom contracted Corrupted Blood when they attempted to heal others, to healthcare workers that were overrun with COVID-19 patients and became infected themselves.
