Below the Root is a childrens book by Zilpha Keatley Snyder in 1976. It is the first book in a trilogy about Greensky, a mythical planet where the trees grow very tall and the people live in them.
It is also a computer game based on the book and Greensky triology, produced in 1985 by Windham Classics and published by Spinnaker Software. This game was commonly played on the Commodore 64 and was popular for it's unique gameplay and non-violent, adventurous theme.