The best open source alternative to World of Warcraft is Ryzom, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to World of Warcraft and five of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to World of Warcraft are Daimonin (Free, Open Source), Stendhal (Free, Open Source), Evol Online (Free, Open Source) and PlaneShift (Free, Open Source).
In Ryzom there are no classes to choose. Develop all the skills of your character harmoniously or choose to concentrate on one skill and become a master. You are not forced to choose a faction when you create your character. Join a faction during your journeys, or not. Represent entire series of Ryzom games.
The goal of this project is to create an ever evolving 2D MMORPG, constantly trimming the sails on the journey through the vast online world. The name, Evol Online, describes this effort to always adapt and explore new routes and ideas.
PlaneShift is a Free Massively Multiplayer Online Role Playing Game. Free? That's right, by making the software's code available for all, PlaneShift allows anyone to improve the game for the benefit of all. So, what have you got to lose? Try it today.