A computer system is provided that stores data for a plurality of virtual objects and elements that are positioned within a virtual space. Each of the virtual objects can adopt different states depending on which elements are determined to have collided with the virtual objects. Once it is determined that an object is collided with an element a further determination is made as to whether that element effects the virtual object. If the element does affect the virtual object, then the state for that object is updated. Further, a new element is then generated based on this change in state of the virtual object.