This Alexa sample skill is a template for a basic quiz game skill. Provided a list of interesting facts about a topic, Alexa will quiz a user with facts from the list.
You can see an example of this skill in action - just enable the United States Quiz from the Alexa app.
Each skill consists of two basic parts, a front end and a back end. The front end is the voice interface, or VUI. The voice interface is configured through the voice interaction model. The back end is where the logic of your skill resides.
There are a number of different ways for you to setup your skill, depending on your experience and what tools you have available.