Generation Z (my 10 year old nephew’s generation) doesn’t get decoder rings, but they get secret messages to decode in this show – one of the best things to hit kids TV in a long time. They have a character named “Bill Cipher” who is a four dimensional being that we only see in 2 dimensions in our 3 dimensional Universe and they have secret messages to decode all the time in it. Awesome stuff.
https://www.youtube.com/watch?v=ZtlX1pujSr4