Makahiki (2009 – present) is an open source “serious game engine for sustainability”. It provides a framework for creating serious games for the purpose of education and behavioral change regarding energy, water, food, and waste generation and use.
The following image illustrates the home page of an energy challenge created using Makahiki:
Makahiki: An Open Source Game Engine for Energy Education and Conservation, George E. Lee, Yongwen Xu, Robert S. Brewer, Philip M. Johnson, CSDL Technical Report 11-07, January, 2012.
A complete list of Makahiki publications is available here.