But back to the real-world hardware at the center of this evolving Mixed Reality game: the gumball machine. 

You're not sure how a gumball-style machine came into your head, but you know you aren't the first person with this idea: to remake the classic corner-store fixture with new technology.

The earliest version you can find is a 2012 project in Make: magazine: the Secret-Knock Gumball Machine.

The idea behind the Secret-Knock Gumball Machine is that it dispenses a gumball only when the secret rhythm ("Shave and a Haircut") is knocked on its front panel. A pretty cool project

The original DIY gumball machine

This was followed two years later by a refresh, by a Make: intern named Sam Scheiner

Gumball Machine #2

In 2017, another version surfaced, on Hackster, controlled by text, via IFFFT: Text Machine, Get Gumball

Here's a view from the inside:

Gumball Machine #3

Giants, all. 

Humbling.

But you have your own idea. 

What you are interested in, above all, is connectivity. So you eliminate the "knock" part.

Your secret, you are starting to think, would be a secret word, harvested from one of the many augmented reality images placed around District Hall.