I have started a community developed video game based off the Eclipse Phase cc-by-nc-sa license. The game is designed to be completely community driven from the start so theres not much decided about it yet. The project is currently named Cybernetic Cephalopod or CyberSquid for short. This is just an alpha code name that will be changed when theres more decided on the story.
CyberSquid is being community devolved and every one is welcome to contribute. In fact, it will only happen if people do so. Currently there are no real rules for submissions. Generally the person who provides the material has the greatest control over the nature of that material. If there are disputes they will be handled democratically, according to the games Constitution. Community development tools are being used to make sure that mistakes can be easily fixed, so don't worry about it just to it! For more information on how to contribute see here or read below.
Pure information, such as story, map sketches, and the web pages are hosted on WikiDot. This allows everyone to easily modify the ideas held within. To work on pure information create an account on WikiDot. Then click "edit this page". This is something that any one can very easily do, so just give it a go. Specifically the Game Design Document can be edited here.
Theres not much of a game yet, but if you want you can download the alpha. You will have to use Subversion and UpBge, the same way you contribute art and code. If all you want to do is download, then you don't need an account. More information can be found here.
Basically, to help you should create an account on WikiDot, another one on OurProject, then join the project on the project page. Remember, this will only happen when people like you actually contribute!