The Unity Playground is a personal project I've been developing as a resource for my activity of Evangelist, and also to complement the volunteer work with children in tech such as CoderDojo. Initially thought for kids (it was called the Kids Playground), in the last year the Playground has been used by me and other people around the world to deliver workshops to both young and grown-up beginners.
What is it
It is a collection of simple scripts to create 2D physics games, intended for giving workshops to an audience of beginner game developers to quickly enable them to make games in Unity. It is intended to be as flexible as possible, not enforcing a specific game genre apart from the obvious constraints of being 2D and physics-powered. It contains a lot of scripts that perform atomic tasks (that is they do mostly only one thing) so you can combine them to create any kind of gameplay.
That said… the audience should already have an idea of how Unity works, the Editor interface, the concept of GameObjects, Components, the Scene View, Play Mode, and so forth. It might be useful to guide them through these concepts before letting them play with this project.
Where to find it
The most convenient way of getting the Unity Playground is to download this .unitypackage. In the future, it will be published on the Asset Store.
If you want to follow the development and contribute to it, the full project currently resides on Github at this address: github.com/UnityTechnologies/PlaygroundProject.
What it contains
The project contains a collection of scripts, each one with their custom Inspector. Additionally, it provides a bunch of graphics (made by Kenney), but you can feel free to add your own or substitute them altogether. It also comes with a collection of Cheatsheet images that can be printed and used as a reference when giving the workshop.
On the Github page for the repository you will find a Wiki with instructions on how to use the Playground.