I'm the guy who runs the Eressea strategy games, and my current sleeper project is a return to the original Atlantis 1.0 code, for which I have a major redesign in the desk drawer. I ran a trial game earlier this year, and I'm trying to get through a list of planned changes for another milestone build and a second game sometime next year.
That is actually not the home page, it's the website for a graphical tool that many or even most most players use. It is built by players as a third-party offering. The Eressea homepage is http://www.eressea.de/ and it is in terrible shape. I need to update it, but I just hate making web pages.
The source code for the game server is at https://github.com/eressea/server and it;s free for use by anyone who likes it.
But before anyone goes and tries to run a game with that, please talk to me! I have two decades of experience with half a dozen games operated, and I am super happy to help anybody out who is willing to give this game a chance.