To help teachers engage students in discussions about sustainability, the authors designed Fields of Fuel, a multiplayer, web-based simulation game that allows players to explore the environmental and economic trade-offs of a realistic sustainable system. Computer-based simulations of real-world phenomena engage students and have been shown to support student learning (Gee 2003; Squire 2006) as players manipulate the inner workings of complex systems and receive real-time data about how the system behaves (Wilensky and Stroup 1999). The Fields of Fuel game explores sustainability around the issue of fossil fuel consumption (Wood, Long, and Morehouse 2004) and related climate change (IPCC 2013). Food crops like corn can be used to produce ethanol as a supplement to or replacement for fossil fuels. However, researchers are also working to make liquid fuel from inedible plants and plant parts, such as switchgrass ("Panicum virgatum") and corn stalks. This "biofuel" could ultimately replace one-third of the oil used for transportation (DOE 2011). There are still questions about how to produce large quantities of bioenergy crops in ways that are environmentally and economically acceptable for the global community. In the game, students (or groups of students) take on the role of a farmer with multiple fields attempting to raise and sell crops (energy-dense corn, eco-friendly switchgrass, or cover crop), and manage fields sustainably, making decisions about such factors as fertilizer use and crop rotation. In multiplayer mode, several farmers interact in a shared environment. Individual player choices affect their own fields and those of the surrounding players. The game is freely available online (see "On the web") and can be played on most web browsers. Each round of gameplay represents a year in real time and can take as much class time as the teacher allows, with students taking from 30 seconds to 10 minutes to make a planting decision. Fields of Fuel is appropriate for various high school courses including environmental science, biology, economics, and agriculture.