in reply to Perl and The Lacuna Expanse
I'm not aware of any involvement the OP has in the project, but I worked on multiple parts of the Lacuna Expanse code and gave the talk on it at YAPC::NA 2012.
The backend code is all written in Perl, using modern techniques and modules. It communicates with the clients using JSON-RPC 2.0. The API is open, allowing users to develop their own tools aside from the standard clients.
All of the components are open source and available on github:
All of the game art is also available for use with custom clients.
The community has also created a set of CPAN modules for interacting with the game through perl: Games::Lacuna::Client