Please remember that development of Liquid War 6 is a volunteer effort, and you can also contribute to its development. For information about contributing to the GNU Project, please read How to help GNU.
Here's a short list of todo items. It is probably too early to start hacking the core engine itself, for it is still under heavy development, might undergo major rewrites, and it's hard for documentation to keep up with the reality of the code. However, there are still many things to do.
Feel free to join the mailing-lists, this is clearly the best place to start with.
There's also a list of opened tasks on Savannah at http://savannah.gnu.org/task/?group=liquidwar6 which you can browse online. Maybe there's some task for you!
Alternatively, you can contact Christian Mauduit.