section_path: Gameplay elements and classification/Rules and aims
section_name: Rules and aims
paragraph_text: Rules and aims
  
  Games are often characterized by their tools and rules. While rules are subject to variations and changes, enough change in the rules usually results in a "new" game. For instance, baseball can be played with "real" baseballs or with wiffleballs. However, if the players decide to play with only three bases, they are arguably playing a different game. There are exceptions to this in that some games deliberately involve the changing of their own rules, but even then there are often immutable meta -rules.
  
  Rules generally determine the time-keeping system, the rights and responsibilities of the players, scoring techniques, preset boundaries, and each player's goals.
  
  The rules of a game may be distinguished from its aims. For most competitive games, the ultimate aim is winning: in this sense, checkmate is the aim of chess. Common win conditions are being first to amass a certain quota of points or tokens (as in Settlers of Catan), having the greatest number of tokens at the end of the game (as in Monopoly), or some relationship of one's game tokens to those of one's opponent (as in chess's checkmate). There may also be intermediate aims, which are tasks that move a player toward winning. For instance, an intermediate aim in football is to score goals, because scoring goals will increase one's likelihood of winning the game, but is not alone sufficient to win the game.
  
  An aim identifies a sufficient condition for successful action, whereas the rule identifies a necessary condition for permissible action. For example, the aim of chess is to checkmate, but although it is expected that players will try to checkmate each other, it is not a rule of chess that a player must checkmate the other player whenever possible. Similarly, it is not a rule of football that a player must score a goal on a penalty; while it is expected the player will try, it is not required. While meeting the aims often requires a certain degree of skill and (in some cases) luck, following the rules of a game merely requires knowledge of the rules and some careful attempt to follow them; it rarely (if ever) requires luck or demanding skills.