No fixed physical server locations. Ad hoc solutions. Security. Anonymity.
Build a javascript based server, complete with communication stack, encryption, and processing, to enable all this. The code could be easily distributed by including it on any (and many) web page. Running it is just going to a web page with the code on it and giving permissions for the code to do its thing.
It’s important not only because of the constantly connected world we live in, or the increasing government prying into our private lives but also as an important concept and a way of thinking.
Games that are fun to play and teach the player many aspects of encryption. The more games they play the more complex concepts and techniques they learn.