Gamification turns a real-world activity into a game to make people more likely to do it. Over the past five years, utilities and third-party providers have developed scores of games that motivate and encourage people to save energy. This report describes and analyzes 22 of these games in depth and surveys 31 others. It takes program designers through the steps of developing a game, explains how games motivate players to reduce their energy use, and analyzes the characteristics of the most successful gamified solutions. Preliminary evidence indicates that gamified energy efficiency programs can achieve savings of 3–6% among a sizable number of participants.