Well this isn't developing a game from scratch, but it would be awesome if someone could pick this up and work on it.
It's framework for multiplayer for Fallout: New Vegas, but the author has quit and gave the OK for anyone to pick it up and work on it but it will need major fixing.
http://www.nexusmods.com/newvegas/mods/45511/?This thing allows for server-side scripting in C++ and/or PAWN too.
All and all it seems like this would be AWESOME to do.