Ryzom is a Massive Multyplayer Online Role Playing Game (MMORPG), a beautiful one, with a very big universe and a lot of users. With the help of FSF, Winch Gate Properties, the copyright holders of Ryzom, released the server and the client under the Affero GPLv3 (Fabrizio is right, it’s a good license for modern networked world) and now Ryzom is free, as in freedom. Not free as in beer. As Peter Brown said in FSF’s announcement
If you want to run your own server for the game, you have the software to do that, but you won’t really have any world data—information about geography, special places, characters, quests, items, and so on—to run it with.
It makes perfect sense to sell access to such data, not software licenses. All gaming companies should learn from this. Meanwhile, have a look at the Ryzom videos and if you’re a fan, start playing.