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quiz vs the machine

Gold1390

System Design

Matchmaking By Rating

Pairing players of similar skill so matches stay competitive.

5 min read · core · beat Gold to climb

Skill as a number

A matchmaker tries to create balanced matches where each side has a fair chance. To do this it summarizes each player skill as a rating. Systems like Elo or Glicko update the rating after each game based on the result and the opponent strength.

Rating plus uncertainty

  • A pure point rating cannot tell a steady veteran from a brand new player who happens to share the number.
  • Glicko style systems add a rating deviation, a measure of uncertainty, so new players move fast and settled players move slowly.
  • The matchmaker prefers opponents whose ratings overlap within the uncertainty range.

Widening search over time

A player should not wait forever for a perfect opponent. The matchmaker widens the acceptable rating gap the longer someone waits, trading match quality for shorter queue times. This widening is the core tension explored further in the pools and queues lesson.

Key idea

Rating based matchmaking pairs similar skill players, uses uncertainty to handle newcomers, and widens its search over time to bound wait.

Check yourself

Answer to earn rating on the learn ladder.

1. What does rating deviation in a Glicko style system represent?

2. Why does the matchmaker widen the acceptable rating gap over time?