World of Warcraft developer Blizzard has taken aim at one of the biggest WoW private servers, suing its creators for alleged copyright infringement and citing recent efforts to “cannibalize and disrupt Blizzard’s WoW player community.”

The server in question is Turtle WoW, an ambitious private-server version of 2006-era WoW that has been active since 2018 and features fan-made expansions, additional playable races and classes, and new zones. Turtle WoW’s creators recently made waves when it announced Turtle WoW 2.0, which aims to remake its version of the original, “vanilla” WoW in Unreal Engine 5. According to a Turtle WoW social media post, one of its most recent server launches hit 13,000 concurrent players.

Blizzard’s lawsuit, filed in California on August 29, alleges the creators of Turtle WoW have created “an entire business on large-scale, egregious, and ongoing infringement of Blizzard’s intellectual property.” While Turtle WoW is technically free, it does feature an in-game shop where players can donate to the developers in exchange for premium currency.

“Recently, Turtle WoW has been brazenly escalating its efforts to cannibalize and disrupt Blizzard’s WoW player community by, for example, increasing its social media presence, partnering with videogame influencers, and actively promoting a new version of its infringing game, Turtle WoW 2.0,” Blizzard’s lawsuit states.

In the lawsuit, Blizzard is attempting to take aim at Turtle WoW’s creators, despite Blizzard not being entirely sure who is behind the project. The lawsuit states that Turtle WoW claims to operate out of Kazakhstan, but that Blizzard believes that to merely be a shell company that “serves as a smokescreen to conceal the identities of the individual defendants while also acting as a conduit for monetary and other transactions related to Turtle WoW.” It proceeds to list several specific defendants from various countries it claims to be involved, but also “Doe Defendants” that includes “individuals whose real identities are not yet known to Blizzard.”

In a statement on the Turtle WoW Discord (via PC Gamer) posted a day after the lawsuit was filed, Turtle WoW team member Torta, who is mentioned specifically in the lawsuit, said the private server is “here to stay.”

“Challenges come to us often, and each time we are prepared to face them,” the statement reads. “We remain fully committed to delivering the Turtle WoW experience that you’ve come to love over the years.”

Turtle WoW isn’t the first WoW private server to be targeted by Blizzard. It infamously shut down a server called Nostalrius in 2016. Several years later in 2019, Blizzard would officially launch WoW Classic, an official old-school version of WoW similar to the one that Nostalrius looked to preserve.