A legal threat from Blizzard will see one of the most popular "pirate" servers for World of Warcraft shut down.

For about a year, the Nostalrius Begins server has provided World of Warcraft fans with version 1.12 of the world-conquering MMO – a version of the game that existed way back in 2006, prior to the release of expansion The Burning Crusade.

According to the Nostalrius Begins team running the server, it has 800,000 registered accounts and 150,000 active players.

The French ISP hosting the pirate Nostalrius server recently received a formal letter from French and US lawyers acting on behalf of Blizzard Entertainment that request it shut down the server, citing copyright infringement. A lawsuit was threatened should it not comply.

The letter didn't exactly arrive out of the blue: hosting private servers is explicitly against Blizzard's terms of use. As such, the Nostalrius team will shut down the servers on April 11 – assuming the ISP doesn’t pull the plug before that.

“It feels kind of unreal, but we want to continue to serve our players as we did, and the best we can in the remaining time,” the team wrote.

“What will happen next? This time, we have no plan for the future, and will have to rely entirely on our community and/or the private server scene.

“We know the time you spent here, the guilds you were part of, and these people with whom you have shared experiences with. We know the strength of these links, and we also know that they do not need a special WoW realm to survive.”

The team pledged to release the server source code and anonymized player data, so that the community had the option to form Nostalrius elsewhere.

“Nostalrius was all about the nostalgia and memories of the glorious vanilla days,” the team said.

“We don’t know if you truly felt like it was the glory days while playing here, but we hope that you will keep good memories of the time spent here. Once again, we can all be proud to have been part of the Nostalrius journey, no matter how much time was actually spent ‘in-game’.”

Nostalrius also posted an open letter to Blizzard urging it to changes its policy regarding legacy servers.

“We never saw our community as a threat for Blizzard,” the letter reads.

“It sounds more like a transverse place where players can continue to enjoy old World of Warcraft's games no longer available, maybe until a new expansion appears; a huge and powerful community of fans that remains attached to future Blizzard games, as we have in no other gaming company.

“We don’t have the pretention to come up with a complete solution regarding legacy servers that you and your company didn't already think about, but we'd be glad and honored to share it with you if you're interested, still on a volunteer basis.”