Hi Neil and Bjorn,
FSM design by Bjorn is interesting but I wonder if it is too sophisticated for many people (including me 
) who are not familiar with graph theory.
I recently posted one example, where I showed a simple FSM using a dictionary. I think it’s too simple for you, but it’s easy and so enough to understand the essence (Python programmers know about dictionary). The graph theory model would be great if people understand the essence and want to go deeper, such as AI, ML, and much more.
So, I propose some introductory examples and a challenging problem. e.g.,
- A gatekeeper problem (two states, two inputs)
This model is very traditional (at least I read it more than 20 years ago!). - A traffic light (three states, one input)
As shown in the previous post. - A vending machine (two states, many inputs)
- A number guessing game (many states, many inputs)
I’ve been thinking about a problem that is practical enough, a bit hard, and challenging for many. I have created one use case for OpenGL UI using FSM.