Skip to main content

Core concepts

Idem's algorithm finds optimal matches by not only looking into currently queueing players, but also predicting incoming players and their respective skill level. Hence, it can deliver better matches at shorter waiting times than traditional benchmarks. The central trade-off for any matchmaker is between the players' waiting time in the queue and the quality (proximity in skill) of the matches created. With hourly fluctuation of players flowing that also vary in (skill, location etc.), this creates a complex algorithmic problem to solve.

Fixed 'target waiting time'​

Idem's matchmaker's objective is to guarantee a similar (and customizable) matching speed for both top-players and average players ("no one is ever too good"). For this reason, waiting time is considered a fixed target value, being set by the developer. The developer decides which waiting time gives the user a good experience. Idem adapts its parameters accordingly and will return the best matches possible while keeping the average waiting time on this target. This guarantees consistent queueing experience for players even when the number of players varies throughout the day.

Automatic parameter tuning​

The only parameter that is required to be set by the game developer is the 'target waiting time'. The matchmaker automatically tunes all its other parameters on the fly, depending on the anticipated inflow volume and skill of players.

Serving top-players​

In most matchmakers, the best players are at a systematic disadvantage. Since they are in the right tail of the statistical distribution of skill, only a fraction of other players coming to the queue are considered suitable to play with them by traditional algorithms (e.g. the ubiquitous "expanding MMR radius" algos), which leads to prohibitively long waiting times for top-players. Idem's 'target waiting time'-concept ensures that top-players get significantly more game play. This ensures retention for the most valuable players such as highly skilled streamers and potentially pro players.

Why good matchmaking matters​

The quality of matchmaking can significantly impact the players' experience. It affects both waiting time and the players' satisfaction with their opponent. Also, a poorly designed algorithm introduces variance in both of these dimensions, which creates additional dissatisfaction with players. With typical algorithms based on an expanding MMR radius, matchmaking quality becomes inversely correlated with waiting time. This introduces another bias as players may become aware of that and manipulate matchmaking by constantly reset their queue.

Activision on the importance of matchmaking in Call of Duty:
https://www.activision.com/cdn/research/CallofDuty_Matchmaking_Series_2.pdf

Grubby on matchmaking
Grubby - eSport-pro and RTS legend, turned streamer - talks about his experiences with matchmaking, the fundamental concepts, and common misconceptions.



Comparison to other methods​

Many matchmaking methods suffer from the following problems:

  • Fluctuating waiting time: Waiting time massively varies depending on time of day
  • Disadvantage of top-players: The best players experience exponentially longer waiting times, if they get matched at all. Significant down-side if streaming is part of the sales-strategy
  • Expanding radius: Many matchmaking algorithms expand the radius of "acceptable skill-difference" with the time a player is waiting in the queue. This leads to top-players systematically waiting longer. This is an inherent design-flaw of the expanding radius' method.