Earlier quoted context omitted.
There are multiple private server implementations. Blizzard does not hunt them. They are on github, you can run it in your basement and play with bots and some friends. I don't know if that presents a copyright violation, but as a matter of fact, Blizzard doesn't care enough to even submit a DMCA to GitHub. Funny fact that both Blizzard and GitHub nowadays owned by Microsoft, so in the end, Microsoft hosts private se…
Maybe I'm splitting hairs, but GP called it a copyright violation and my understanding is a "clean room" reverse engineering for interoperability was fair use and not a copyright violation. Yes this does threaten Blizzard's business model so I understand why they'll go after Turtle, but that doesn't mean we have to care or let them prosecute Turtle for Contempt of Business Model. Now, if Turtle used Blizzard's WoW tr…
To my understanding, reverse engineering algorithms and interfaces is not a copyright violation since those cannot be copyrighted (i.e. fair use is not relevant). However, a WoW server also distributes e.g. quest texts, which most certainly are copyrightable, since the collective of all quests is comparable to a fantasy novel.
In backend terms (which isn't really relevant in court but helps illustrate the division), every WoW server is said to have a "core" that contains the gameplay logic (netcode, movement, hit rolls, object interactions, etc.) and a "world database" (item names and stats, NPC names and stats, quests, etc.). The core might be considered a collection of clean room reverse engineered algorithms, which aren't copyrightable. However, the world database is full of copyrighted material, and a server distributing that data to clients will violate Blizzard's copyrights. You could avoid this by deleting all of Blizzard's stuff from the world database and writing your own content, but it's not relevant here since Turtle WoW didn't do that.
Nonetheless, vbezhenar's point stands because there are open source server implementations that host both the core and the database on Github, see e.g. https://github.com/cmangos/mangos-tbc and https://github.com/cmangos/tbc-db.