“…In the third mode, 'player vs. player', players directly interact with one another through the system, e.g. "One-on-One" (Fogtmann et al, 2011); "Spots mode" (Ishii et al, 1999); "Space Ball 1" (Izuta et al, 2010) and various other systems (Altimira et al, 2016;Mueller and Walmink, 2013, 2008a. In the fourth mode, 'unilateral competition', multiple players are pitted against a single player, as for example in the traditional game of "Tag" (Konkel et al, 2004;Delden et al, , 2016a.…”