Game ladder

A ladder tournament (also known as a Ladder League, game ladder) is a form of tournament for games and sports. However, unlike a tournament, that usually has an element of elimination, a ladder competition can go on indefinitely. In a ladder competition, players are listed as if on the rungs of a ladder. The objective for a player is to reach the highest rung of the ladder. A ladder competition is similar to a pyramid tournament, except that unlike a pyramid tournament, only one player can occupy any given rung and whom a player may challenge is not as tightly restricted as in the pyramid system.

The competition proceeds via a system of challenges. Any player can challenge a player above him or her on the ladder. If the lower-placed player wins the match, then the two players swap places on the ladder. If the lower-placed player loses, then he or she may not challenge the same person again without challenging someone else first. There is a limit as to how many rungs above themselves players may challenge. When first setting up a ladder tournament, usual practice is to place the more skilled players at the bottom of the ladder, so that they have to play to work their way up.

Ladder competitions suffer from two problems, both resulting from the challenge system. The first is that the ranking at the end of the tournament (or after a sufficiently long time) may not necessarily reflect the actual rank of the players, since it is not guaranteed that enough challenges, or the appropriate challenges, have been made to correctly "sort" the ladder. However, if the balance between number of participants and duration of the competition is defined properly, this usually results in a representative ranking. The second is that some players may make challenges more frequently than others, or are challenged more frequently than others, meaning that not all players may be challenged, and that not all players may play the same number of matches.

Ladders are typically used in sports such as squash and badminton. Usually challenges should not or can not be declined.

Other systems calculate a numeric rank for each player. This removes the limitation on which matches are allowed. The most widely known system of ranking players is the Elo rating system, which is used for Chess and Go. Every player in the Elo rating system receives a rating based on his or her win/loss record, which establishes his or her position (or level) on the game ladder. Numerous efforts have been made to design better game ladders by analyzing the statistical correlation between relative ladder levels and a player's expected performance.

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