  The third element of a game is the (constitutive) rules. Rules provide a complete account of what means are permitted and not permitted within the game. They establish what means can be employed to achieve the pre-lusory goal of the game. These limitations on the permitted means make the game possible, for they erect (unnecessary) obstacles that participants attempt to overcome in the game. For instance, boxing rules disallow the use of weapons, such as knives or firearms. This ensures that the sport is a punching contest. The laws of soccer permit the use of any body part other than the arms so that the ball is played predominantly with the feet. In addition to constitutive rules, Suits argues, there are rules of skill, which establish how to play the game well. Such rules are rules of thumb that a coach may advise a player to follow to help her better execute the skills of the sport (e.g. keep your eye on the ball, follow through after impact, accelerate through the finish line).