Many more forms of interaction can be imagined, even by just applying the universal simulation principle. Video games have already provided many ideas for interaction via a standard game controller. Beyond that, the Nintendo Wii remote has been especially effective in making virtual versions of sports activities such as bowling a ball or swinging a tennis racket. What new interaction mechanisms will be comfortable and effective for VR? If displays are presented to senses other than vision, then even more possibilities emerge. For example, could you give someone a meaningful hug on the other side of the world if they are wearing a suit that applies the appropriate forces to the body?