To provide an image producing system capable of producing images in which state changes occur in objects according to impact positions with a smaller data quantity and computation load and an information memory medium.

This image forming system produces the set object image constituted by setting of plural part objects. The system includes a change object determining section 120 which determines the part object existing within a prescribed range including the impact position as the object for changing the display mode and an image producing section 160 which executes image production by changing at least one among the shape, color, position, rotation, direction, moving direction and speed of the part object determined as the object for change. The set object may also be constituted by closely combining the part objects of plural shapes. The constitution as the single object before the impact is exerted and the image production as the set object after the impact is exerted are equally well.