The game Overgrowth has become open source (at least part of it, textures, models or audio are not included). I'm not posting this in the Free Open Source Games thread because the full game isn't free, neither even DRM-free...
But it's good news anyway, specially for people with interest in developing.

Announcement Video

Overgrowth GitHub repository

It is DRM-free though.

A DRM-free build is sold by Humble Bundle.

Thanks for the info, pals. I didn't know.
:)

It's also DRM-free on Steam.