Heh, I’d wondered the same thing (re a pair of postcards), My comment had crossed in the timing of your reply.
The writing at the top middle doesn’t appear to go with anything, but you know how this stuff ends up in thrift stores or wherever... somewhere along the ownership chain, people make notes.
A game by mail, sounds like a fun way to stay in touch. Much more interesting than how-are-you-I-am-fine mail. :)
Yes, the fishway note seems to be written in ballpoint pen and in another handwriting. Fishway isn’t the name of a town, so maybe someone was just jotting down a note about a fishway which I just learned the definition of. Had no idea about fishways/fish ladders (and a few other synonyms). Still learning something new every day.