I wonder if this could be restarted (alas in English...). Any English-speakers who have experienced the mechanics of these kind of games? It's been so long that I received a 'postcard' that the idea almost is thrilling.
Pages 70 & 71 of "Signal: communication tools for the information age" (A Whole Earth Catalog) have details.
I'll take a photo and put it up on Imgur, because the official site is broken.
Here's a link, sorry for the poor photography: https://imgur.com/a/4miM4vP