In the US, it is illegal (copyright infringement) to run a private server. https://arstechnica.com/gaming/2010/08/the-88-million-server-private-wow-server-op-l

In the US, it is illegal (copyright infringement) to run a private server. https://arstechnica.com/gaming/2010/08/the-88-million-server-private-wow-server-op-loses-big/ https://arstechnica.com/gaming/2010/08/the-88-million-server... And given that, a lawyer could argue that paying to play on (or even donating to) a private server is contributory copyright infringement. I don't know if that has been tested in court. https://en.wikipedia.org/wiki/Contributory_copyright_infringement https://en.wikipedia.org/wiki/Contributory_copyright_infring... But oftentimes you can get away with it; few game companies go after small private servers.