The main source code of Akagoria is available in the Akagoria project on GitHub.
Akagoria uses Gamedev Framework (gf) as its main library. It is developed at the same time as Akagoria.
The developer's documentation is intended for people developing the game. It contains many information about about the world of Akagoria is built.
If you want to talk directly with the developpers, you can join the #akagoria IRC channel on freenode.