Abstract: Experimental game theory explores decisions-making intelligence in simulated laboratory scenarios that engage participants’ imagination. However, do choices differ when subjects face real-life situations? and decisions when subjects are exposed to the real life? Hence, the objective of this study was to determine the effect of physical involvement on decision-making. Therefore, this study aimed to assess the impact of physical engagement on decision-making. Fifty-eight athletes competed in a paradoxical motor game, the Alligator Game, conducted underwater in a swimming pool. Depending on whether they broke the surface before or after a line 15 meters from the wall, they won a certain number of points according to a matrix known to them. During the confrontation, the players were either row-players or column-players (depending on their choice in the matrix). Depending on what type of player they’ve chosen, they had tactics to maximize their number of points won. They could, if they wanted to stay in static apnea (like an alligator), to see the decision taken by their opponents in order to choose the best move. Participants also played this game beforehand in the locker room (what would they do theoretically if they were confronted to this situation?). Statistical analyses of the 174 water confrontations showed that (i) alligator players did not consistently apply the best tactic (Nash’s equilibria), (ii) the best players did not play as they had announced in theory. The best free divers maximized their earnings by forcing the decisions of the other players. In conclusion, decisions made were, above all, subordinated by the person’s ability to put them into place: “without technique, no tactics”.