Changes in the design and implementation of instructional simulations on the PLATO IV system have evolved in the direction of more explanation, evaluation, and streamlined simulation. Student pressure to use their own problem solving processes, the practical system limitations of producing environmentally complex simulations, and student confusion when no guidance was given have all contributed to a change in instructional goals and new directions in the development of instructional simulations. New formats combine feedback on each action taken, guidance or explanation in reaching the goal, and less realistic simulations. Instructional goals are now emphasizing concept learning rather than skill in problem solving. Current trends indicate continued use of simple simulations with the increasing use of non-traditional formats, and the use of sound, as well as more individualization of lesson development. Thirteen references are included as well as a selected annotated listing of instructional simulations and games arranged by subject areas. (BK)