Elo rating systems and how to manipulate them

Competitive games need to match players of similar skill. This is called matchmaking. For matchmaking to work, the game needs knowledge of each individual’s relative skill level. Most games use a version of the Elo rating system–invented for ranking Chess players–to determine individual skill. The system assigns an Elo rating to each player and adjusts it after each match. In theory, a player’s Elo goes up when they achieve an unexpected positive outcome and goes down when they suffer an unexpected negative outcome. For instance, a highly ranked player drawing with a lower ranked player leads to the lower ranked player earning Elo and the higher ranked player losing Elo.

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