Corrupted Blood Incident

Work in progress :)

Problem overview

World of Warcraft (WoW) is a massively multiplayer online role-playing game (MMORPG) released in 2004 by Blizzard Entertainment. Corrupted Blood was a virtual epidemic in the World of Warcraft an it began on 13 September 2005, when Blizzard introduced a new raid called Zul'Gurub. Outbreak originated in the new dungeon and since then it is known as the "Corrupted Blood incident. Dungeon boss Hakkar was a blood god also known as the Soulflayer, who had, among his arsenal of weapons, a "debuff" spell called "Corrupted Blood." Infected players would suffer damage at regular repeating intervals, draining away their health. Debuff also damaged other near by players and rapidly spread. It was unintentionally released into the larger game world and became the first disease to affect entire servers.

The "Corrupted Blood incident" was not intentional. The biggest factor in the rapid spread of the disease was a glitch in the programming. Non-playable companions of players could became infected and could carry debuff out of the dungeon. This turned them into asymptomatic carriers and a form of vector for the debuff. As Corrupted Blood infection spread uncontrollably. During the epidemic capital cities were abandoned as players rushed to evacuate to the relative safety of the countryside, leaving urban areas filled with dead player characters.

Blizzard had to fix the problem by applying hot fixes, patches and multiple hard resets of the servers. The plague ended on 8 October 2005, when Blizzard made pets unable to be affected by Corrupted Blood debuff. Debuff could not get outside of Zul'Gurub. The incident has helped many scientists model real-life epidemics since they would be able to draw on hard data showing how players actually responded during an outbreak.