Not sure if my adding to this is going to bump it up the message board, but I just saw the same ad today and I too am super curious about what this game was like! All I can find is that it was published by either "Sage Systems" or "Knights of Chivalry" (according to the wiki List of play-by-mail games)... though the advert says "Sanctuary Games" so who knows? I would assume that two of them are companies running the game, and one published and ran it?
Unfortunately that's all I could find. Googling any of those publishers doesn't show much of anything.