I think I also like this idea of developing an online game (I have never heard of this particular game though) because it has very broad perspective on things. Writing a full game would probably involve:

• using databases
• CGI for web interface (with an interface to the database) with cookies and all side issues
• You can even write a custom template system (remember that we are not striving for efficiency, the objective is to learn)
• Socket programming - client and server
• There could be graphics programing involved (let's say displaying user stats in a graph)
• As the project might get big, you also get experience in working as a team as a bonus ;)