[This is the first commercial game I can think of taking this step][link] while the game is still live. All of the Ryzom source including tools, client, and server codebases are fully open source free software. For more, [see the FAQ][link]. It sounds to me a lot like a MUD codebase, and that makes me smile.
I do not see this helping them in the marketplace, but I’d like to see this become a trend. I have a lot of old PC games which are no longer playable due to DRM or other online components which no longer exist.
[faq]: http://dev.ryzom.com/wiki/ryzom/OpenSourceFAQ “Ryzom – OpenSourceFAQ – Ryzom Core Development Site”
[link]: http://blog.ryzom.com/post/575861866/the-mmorpg-ryzom-goes-free-software “Ryzom goes open source”