Virtual plague

A virtual plague or virtual virus is an infection that can be transferred between the characters of players in a massively multiplayer online role-playing game (MMORPG). Just as a disease can spread in the real world, virtual world diseases can spread between characters in these games.

The "Guinea Pig Virus"
In May 2000 the creators of The Sims came under fire from gamers after numerous characters became infected after guinea pig bites. The contagious disease killed many characters and angered the players. Maxis, the game's creators, changed the result of the bite to be a lot less virulent.

"Mystery Virus"
In The Sims, this virus could be called "Silent but Deadly" - it struck without warning. The virus would usually start with a Sim who had been using their chemistry set a lot, or had returned from Vacation Island. It resulted in hacking, coughing, sneezing, and after around 3 Sim days the sim would die and infect the other characters. By many, it has been known to kill off entire neighborhoods.

The "Corrupted Blood" Plague

 * See Corrupted Blood for more information

In September 2005, the Zul'Gurub dungeon was introduced into World of Warcraft, bringing in Hakkar, the god of blood. When this character was defeated, characters present were affected by a spell called Corrupted Blood, which caused 250-300 points of damage for every second the character was infected, and would spread to infect any nearby characters. The infection would only last for five seconds, but characters could become re-infected.

The Corrupted Blood Plague was believed to have begun when a party of players discovered that pets and NPCs could be infected. Infecting a pet, they released it within one of the cities within the game. Low-level characters and NPCs were infected, the former dying almost immediately while the latter became a carrier and were considered a key reason for the plague's rapid spread.

After a few days, Corrupted Blood became World of Warcraft's version of the Black Plague, rendering entire cities uninhabitable and causing players to avoid large clusters of other players, and in many cases, stop playing altogether. It is widely suspected that, due to the curse's peculiar behavior, it was never meant to leave Zul'Gurub - the ability to infect pets and NPCs a side effect unconsidered by the programmers. Blizzard Entertainment tried several times to fix the problem, including imposing quarantine on certain places, eventually finding a 'cure'.

The "Grey Plague"
On Tuesday, October 11, 2005, players in the online game Kingdom of Loathing were greeted by Cristobal Colon, a Christopher Columbus based character, who had recently arrived from across the sea. In what appeared to be a friendly gesture he begin to give out Comfy Blankets, and later sold them for those who didn't get them. For the next three weeks the Kingdom of Loathing was affected by a communicable virus which came to be known as the Grey Plague for its symptom: greying of the player's font in chat and adding a random -cough- to their "speech". The disease was traced to the blankets, but could be spread through messages from infected players (both in chat and the messaging system "kmail.")

The plague came along with the advent of Temporal Rifts, and The Council of Loathing (the kingdom's government) commissioned a temporal rift 28 days into the future of Seaside Town, the game's central location. In the traditional KoL fashion of mixing parodies, the plague was revealed to transform the players to zombies over time, and players traversing the rift were greeted to a post-apocalyptic, zombie-infested world. The game's resident vendor of healing potions claimed to have invented a miracle cure, but it was only a temporary solution.

The Council put out a call to all players to seek a cure. Eventually an inoculation against the disease, Ofuxxor, was introduced, in the form of a blowgun. Players could get it by bringing a dead zombie's pineal gland to the right non-player character and could use it on themselves or on other players. The plague wound down after that, and eventually it was completely eradicated on November 11. Jick has later commented that this plague was just a knock-off of the corrupted blood plague from the World of Warcraft.

The "Zombie Apocalypse"
In Puzzle Pirates, for halloween, a disease was introduced in NPP's that turned the afflicted into zombies. The NPCs and newly-infected players spread the disease rapidly; near the end of the event, most player-controlled characters were zombies. This contagion, unlike the 'corrupt blood plague' and other epidemics mentioned above, was intentional, and there was already an in game cure: a cureall elixir that restored cursed players to human state. Once everybody had become zombies they were divided into seven teams based on skin color, and every time a person from one team beat a person from another team in a PvP puzzle, their team got a point.