Fans of Blizzard’sWorld of WarcraftMMORPG are taking time today to reflect back on one of the most bizarre and fascinating incidents in video game history.

The idea thatWorld of Warcraftis a game that often mirrors social situations and real-life human interaction is nothing new.World of Warcraftguild leadershave cited the game as a major boon to their personal and professional development as people, and the community is strong enough that the MMORPG, over a decade since its release, is still one of the most popular games on the planet. Part of that continued relevance stems from the fact thatWorld of Warcrafthas exhibited its growing pains for the entire world to see, and some of that evolution has involved incredibly bizarre, incidental world events.

Today, gamers on Reddit and other social media platforms have begun discussing and remembering one of the most fascinating video game social experiments ever - and it wasn’t even remotely intentional on Blizzard’s part. The Corrupted Blood Incident’s 11th anniversary falls on today, and it’s a memory of an experience that is a far cry from the refined and overwhelminglysuccessfulWorld of Warcraft: Legionexpansion. One user from Reddit, PapaSmurfington, summed up the drama of the incident with the appropriate level of flair:

“I remember seeing the corpses lining the streets of [Orgrimmar, capital city of the Horde inWorld of Warcraft]. I can still hear their screams.”

Despite the polygonal horror of the Corrupted Blood Incident, many veteranWorld of Warcraftplayers are citing it as one of their favorite memories of the early builds of the game. The Corrupted Blood Incident began when Blizzard introduced a raid boss who infected players with a highly contagious debuff spell called “Corrupted Blood”, which soon spread across the world because of a bug that allowed pets and minions to bring the disease outside of the enclosed raid experience. A virtual pandemic quickly ensued, as the debuff was strong enough to quickly kill low-level players in capital cities while higher-level characters were forced to constantly heal themselves to avoid dying.

The Corrupted Blood Incident lasted a full week before a patch finally quelled the pandemonium, which had seen players begin to retreat into the far reaches of Azeroth to avoid major cities and getting infected with Corrupted Blood. Well before thelive-actionWarcraftmoviebecame a hit in theatres, the Corrupted Blood Incident became the firstWorld of Warcraftfeature to transcend video games and enter the real world - epidemiologists and counter-terrorism researchers actually used the Incident for research on how humans react to epidemics.

While it might seem odd that users fondly remember a time that fundamentally altered the wayWorld of Warcraftusers were able to play the game, many of the Reddit responders have suggested it’s the nostalgia of a world where anything could happen that appeals to them the most. It might not be the product of thenow-retired Chris Metzen’s talented world-building, but the Corrupted Blood Incident was an accident that became an iconic event, a horrific plague that somehow became a symbol of the freedom and unpredictability of a game that gives its players so much power.

World of Warcraft: Legionis available now on PC and Mac.