Advances in computer software allow modelers to design, with relative ease, sophisticated, realistic educational tools. With these advances, new issues arise about how to make this educational software productive and stimulating, without limiting the freedom of the user or creating simply a computerized workbook.Such simulation games have great educational potential for people who play video and home computer games, and sometimes for students in classrooms. The games must address three information levels: (1) real-world details, (2) simulation of model, and (3) conceptual understanding of structure and dynamics. The systems viewpoint on the particular model must be clearly explained; otherwise users will have much fun but learn little. Feedback during the game teaches this system understanding without requiring textbook readings. Such feedback requires new modes of “expert” computer analysis which need to be developed. Other tools need to be developed to help in creation of simulation games and to give the games abilities that they do not yet have, such as access to database of models, pictures, and text, and connections between simulation games.