World of Warcraft – the plague of Azeroth. The most infamous bugs of online games

The Corrupted Blood incident is perhaps the most famous bug in World of Warcraft. The story happened on September 13, 2005 and was related to the boss from Zul'gurub named Hakkar The Soulflayer. He cast debuffs on players and their pets. It made the characters lose HP for 10 seconds. The debuff had another property – it moved on to others within a certain range. Infected people had to avoid friends, so as not to spread the disease to other participants of the rally. At least that was the theory.

In practice, it turned out that a debuff applied on a pet can extend to others, also not participating in the raid. One player whose animal was infected returned to the city and caused an epidemic. His pet not only infected other players; this extra debuff, infected outside the raid, did not disappear after 10 seconds. It didn't end, all the while dealing damage and infecting new people. This led to significant depopulation in Azeroth.

The only way to painfully corrupt your decision was to allow yourself to be killed by the plague, and then avoid all the infected – both players and their pets, as well as NPCs. In the end, some areas and cities in World of Warcraft were almost abandoned – because the community sought refuge from the curse in less popular locations. However, malevolent players never make it easy – groups of them decided to play zombie and their goal was to infect everyone. On the other side of the barricades were healers, who joined the expeditions to treat players suffering the disease.

Eventually, this event attracted the attention of epidemiologists, who, based on the behavior of the community, studied the reactions during the pandemic; the error with the Corrupted Blood spell was also interesting to organizations fighting terrorism.