Eressea has a twitter feed at @eresseadev.
The code of Eressea was built with the idea in mind that different worlds would have different rules and game elements. The three active games make use of this modular design, and each new game introduced some new races, resources, items or experimental new rules. Configuration of the game is done through a mixture of configuration files and Lua scripts, and the occasional addition of more C code to the core game. If you want to become part of the development of the game, or just modify the code to build your own variant, you should join our slack channel to discuss your plans.