Operational gaming is a special type of model-building structured so as to permit multiple simultaneous interactions among competing and cooperating players. If a computer is used, the game situation can be manipulated and the effects analysed by an observer. Open gaming (when there are no constraints to the individual steps) is restricted in many cases to manual operation because the programming effort and the storage required to handle all possible moves would be uneconomic, even if technically feasible. Gaming is an effective means of forecasting the impact of events and new technologies. Games may be used to provide participants with experience in adapting to an unfamiliar environment and making decisions under conditions of uncertainty, and also to develop understanding of basic organizational relationships. Functional games may be used to provide participants with experience in dealing with well-defined problem situations.