The Corrupted Blood Incident


Each of these corpses represents an actual person who paid for this. I'm probably in there somewhere.


I’ve done a lot of posts lately about things I hate, how about something positive? Here’s something I like.

The new card back for Hearthstone, based on Hakkar the Soulflayer.


Well not so much the cardback, it’s decent. There’s better, there’s worse. But the mechanic, idea behind it. The only way to acquire this cardback is to play somebody who already has it, thus contracting the “virus”. It’s a wonderful use of ludonarrative mixed with fun mixed with nostalgia.


A bit of history is in order I think. This is something I’ve wanted to cover for a while and could never find a reason to, and now it’s been gifted to me. Or perhaps it has infected me.


This little chunk of video game history is known to both gamers and professional epidemiologists as the “Corrupted Blood Incident”. That actual professionals who study diseases are interested in this should give you some clue that this is out of the ordinary.


Back when World of Warcraft (WoW) first launched in 2005 it shook the world in a lot of ways. Everyone was excited to get on board and interact with fellow humans in the mythical land of Azeroth, myself included. What wasn’t really planned for, and in hindsight should have been, was that fellow humans are often not the most lovely of people. In fact they're usually dicks. This resulted in a more than a few problems for WoW, as a couple of things became apparent soon after launch.


First was that there emerged an enormous gulf in power level between the more casual people who only logged in for an hour or two a day and the hard core players who sunk 16-20 hours a day, every day. These people very quickly churned through the massive amount of content in WoW in a matter of days, hitting max level and then discovering that once you’d done pretty much everything, there wasn’t a great deal left to do.


Blizzard had always planned for this problem and were already working on new content, but they didn’t expect people to burn through quite so quickly.


So naturally when these players conquered the environment, they turned their attention to their fellow man. Thus began the age of “griefing” - or making life miserable for lower level players just because you could.


A number of lower level player areas became genuine war-zones. Places like The Barrens looked like the Somme. The early player area of Southshore held an unofficial event known as the “Southshore Tug-of-War” where high level players of one faction would come in and start griefing lower level players, then higher level players from the other side would come in to protect them and defend their honour, as it were; and a quiet place that was supposed to be somewhere that you could safely build up your character turned into a hellscape of instant death.


Two sides locked in perpetual conflict and newbies stuck in the middle.


Bored people with an unprecedented combination of both agency and deindividuation turn into complete dicks. Who’d have thought.


But we hadn’t seen anything yet.


Blizzard realised that the lack of late-game content was leading to griefing, and threatening their bottom line, so they rushed to implement something for these people to do at a high level. Enter the first 20-man raid dungeon - Zul’Gurub, and its boss - the eldritch horror Hakkar the Soulflayer.


What happened next created history.


One of the golden rules of video games is if there exists even the possibility of something being exploited, it will be found and abused. Such was the case here.


Hakkar was a reasonable boss fight, nothing truly noteworthy (certainly not in the realms of C’Thun or such), very run of the mill. Blizzard were still finding their feet with encounters. But what was of interest was an ability that Hakkar had: “Corrupted Blood”.


This was meant to be something like a virus, it dealt damage over time and spread from player to player. It was meant as something to divide the player's attention and add an extra layer of difficulty and strategy to the fight. Instead of everyone wailing away on Hakkar they would have to pay attention to the damage this virus was doing and manage the effects mid-fight. Fairly standard raid boss design.


The oversight, which turned out to have massive consequences, was that Corrupted Blood wasn’t programmed to do percentage based damage. It did a flat rate of damage - 250 to 300 damage per tick. Within the raid this acted like the usual percentage based ticks; players in the encounter were usually of a high enough level that they had somewhere around 5000 hitpoints and Corrupted Blood would hit them for something like 5-8% of their health every tick, so it acted exactly like a percentage debuff. Nothing out of the ordinary. Yet. But it wasn’t a percentage debuff.


Through a somewhat convoluted exploit that the initial programmers probably never even thought to check for, it became possible for players to “store” the Corrupted Blood virus and take it out of the Zul’Gurub area. It’s likely the programmers didn’t think to check for this because why would anyone want to take a virus back to town? Isn’t that a bad idea?


Yes, yes it is.


But people can be terrible. Thus one of the first attempts to combat griefing in the game became the most massive case of wide-scale griefing in the history of video games.


People took the virus back to the major cities of the game; the central hubs where essentially all players, regardless of level, congregated to do everything from buy and sell, to repair, to trade, to...well do everything. Every player in the game passes through these points at least once a session. And suddenly there was a pandemic being willfully released in each and every one of them.


Remember how I said that Corrupted Blood did a stock 250-300 damage instead of a percentage? Well it turns out that that isn’t a big deal when you have 5000 hitpoints, but for lower players who only have 200 hitpoints, that’s an instant death. And if you try to resurrect you just get hit again. And again. And again. The virus should have burned itself out quickly as it ran out of hosts, but the high level players would hang around, acting as perpetual vectors for the virus and ensuring that everyone remained sick and dying.


I distinctly remember logging in one day and dying instantly. Then seeing the endless fields of corpses where used to be a bustling center of trade and activity. Then realising that it was futile to fight it and just accept the peace of death until the patch came in.


Blizzard rushed to fix the issue but it took time and for a few days the game was a wasteland. The world of Azeroth had been wiped out by a pandemic and it had hit critical mass in less than an hour.


The CDC, WHO and other fun abbreviations who study infectious diseases for a living took a great interest. Here was a sample set of data they could never dream of - a live dress rehearsal for a real civilisation threatening incident, complete with metropolis level population centers, organic agents acting according to instinct and, disturbingly, the feared section of the population who would perpetuate a deadly disease just for shits and giggles. It was like Christmas for them. Less so the players.

And all because of a single line of code.


The Corrupted Blood incident has entered folklore. It was something I fondly recall having lived through, even if I perhaps didn’t appreciate it at the time. This is a sentiment that was shared by a large number of the player base. Even though the game was essentially shut down for a number of days - usually death to any MMO - this somehow made the game better. It made it seem real. It made it better than life, it gave you an experience you really couldn’t get anywhere else. Something that you could share and talk about and reminisce with.


And that’s why I’m so happy Blizzard have implemented the Hakkar cardback in Hearthstone the way they have. It’s a wonderful bit of history and nostalgia - a card that can only be acquired by interacting with someone who has already been infected. It got me playing as much as I could, against players I probably would never have faced, simply to take part in the experience.


What a brilliant bit of design by Blizzard. Well played. Instead of something invective about your Diablo announcement, I’m instead writing about how good your marketing is with Hearthstone. Tip of the hat to you. If anyone needs me, I’ll be spreading the plague, err...joy, in Hearthstone. Until then chums.

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