Game Glitch Analysis: Corrupted Blood Incident

Corrupted Blood in Ironforge

I would like to first of state that I’m not a big WOW guy. I never really got into the game. However, this event fascinates me to no end. In most games, when a glitch is found, people will try it out and usually get nothing out of it other than an experience (or erased save data), but the Corrupted Blood Incident showed how one small oversight could reign chaos on the world.


September 13th, 2005 – Blizzard just released a new dungeon Zul’Gurub. The dungeon contained a powerful boss named Hakkar (Sounds like “Hacker”) who had a magic spell called Corrupted Blood. The spell was a debuff –  as opposed to spells that would up your stats when another player cast the spell, this spell you drop one of your stats for a certain amount of time. This spell drained your health in significant doses, and had a 100% chance to be passed on to another player. The spell was intended to be localized; the only place you could be afflicted was in the dungeon, and by the time you left the dungeon the spells’ affect would have worn off. Alas, there was one painful oversight that caused mass hysteria.

There was a glitch that allowed you to teleport out of the dungeon and back to town… where other players were going on with their regular lives: buying armor and weapons, planning raids, talking to friends. The people who teleported back from Hakkars’ dungeon brought Corrupted Blood back with them, and the disease spread like wildfire.

Soon, players were losing health like crazy. The lower-level players would die almost instantly, while higher-levels would die slower until they could find a way to heal themselves faster than they were dying. Not only where the players infected, but NPCs and Pets also caught the disease and helped spread the deadly curse. People in desperation tried to leave the server and head to a new one, finding that it, too, was infected. During the span of the epidemic, Corrupted Blood would put 3 servers into a state of panic.

Human Nature

Bodies filled the streets of WOWs’ more popular cities. As a result of the epidemic, the WOW community sprang into action and assumed roles in this outbreak. Players would cast healing spells on large groups of infected players to help them wait out the spells’ effect. Others would guard the outskirts of infected cities to ward off other players. However, there were people out there who help spread the curse, becoming infected themselves, and running into groups of people, or infect the NPCs of a town. Hundreds of players were dying a day without ever setting foot in Zul’Gurub. At the rate the curse was spreading, there seemed to be no easy end in sight.

Pieter Bruegel's "The Triumph of Death"

Blizzards’ Solution

WOWs’ normal gameplay haulted due to the plague. The game became unplayable because the players would have to dedicate their time avoiding the plague. While some people enjoyed the first “real-world” event, calling it “the day the plague wiped out Ironforge,” Blizzard was being bombarded with angry calls, and people abandoned the game until the outbreak was resolved.

Blizzards’ first attempt in getting the plague under control was to make volunteer Quarantines, but too few players took it seriously. Finally the decision came. No matter how interesting this event was, Corrupted Blood had to be stopped. Blizzard did a hard-reboot of the 3 servers and quickly patched the spell.

Even after the main epidemic, small outbreaks still happen, but to a less-devastating effect. Before the release of Wrath of the Lich King, Blizzard created another plague (a Zombie plague), only this one was smaller, less devastating, and harder to spread.

After Effect

With the epidemic ended, the game resumed as normal, however people looked into the “real-world event” as an idea for simulation, new game features, and ways to study how people act in times of crisis. The Centers for Disease Control and Prevention contacted Blizzard asking to see any data they collected on this experiment, not knowing it was a glitch. Blizzard did go on to recreating a new, however controlled, zombie plague. The zombie plague was not as infectious as Corrupted Bloods’, but when a large group of infected approached people, they had a better chance of infecting them too.

People from universities and research centers are looking into the idea of “real-world events” in simulations and games, however, when Blizzard was asked about Corrupted Blood, they responded by telling people “it’s just a game.”

Possible Cause

From my standpoint, this glitch looks to be almost like a design flaw. The teleportation out of the dungeon was definitely the glitch, but it probably wouldn’t have been so devastating if the spell was balanced correctly. But don’t take this as a stab against Blizzard; far from it! Blizzard should be commemorated for this event! They showed how people – themselves included – react when something completely random and devastating (like an epidemic) comes along, and they responded – not as players, but as real people. No one told those people to close infected towns and to provide volunteer services to aide the people afflicted. No one told some players to spread the disease and continue the outbreak.

This event also shows how difficult being a game designer is. No one could of guessed that setting the chance of spread to 100% would be too much, and who knows? Maybe during beta testing they found 99% too little. Its amazing how one-tenth of a unit can make a world of difference when it comes to balancing, and in some cases (case-in-point), it becomes extremely difficult, and the cost of it is dire.

Thats another thing to remember as well – play testing. It’s hard being the developer or the designer and testing the game. You know how the game should act, and you do what you built the game to do. You need people who know almost nothing about your game to try and do everything they can to break it – and that’s just to find gameplay bugs! There are tons of other conditions to consider as well! I talked once to a developer from EA who said in one game, if you wore these clothes in this combination and tried to do this 20 years from now, the game would crash and erase your save data. No joke – there are bugs like that (How he found that is beyond me).


This just goes to show 2 things:

  1. No matter how much you design and safeguard against, there will always be something just slightly overlooked. People will find it, and when they do, you better be ready on the quick-draw with an update.
  2. The human reaction to something in a virtual world can nearly reflect on their actions in the real world. Creating a “Real Life Event” in a game can really change the overall feel of the game – like adding a new layer of immersion. In video games people don’t have to worry about economic recessions and climate change. However when something so familiar to our lives – like an epidemic – strikes suddenly, the player no longer sees it as a game, but as an actual event.

Amazing is the human mind.


Published by


Computer Scientist for Engility, and Indie Game Dev from New Jersey. Loves playing games, and loves making them, too.

One thought on “Game Glitch Analysis: Corrupted Blood Incident”

  1. The reason people reacted like this is because WoW is such an easy game – the players were faced with an actual challenge. It didn’t matter what level they were, it didn’t matter what race they were, religion didn’t matter, gender didn’t matter…. It brought out the humanity in them, a rare thing.

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