Latency is geography
In realtime games, latency is dominated by physical distance. Regional server selection routes a match to the data center that minimizes ping for the players in it, since a far server hurts everyone.
Measuring the right region
- Each client pings candidate regions and reports round trip times.
- The matchmaker prefers a region that keeps the worst case player ping acceptable, not just the average.
- For a mixed group, it may pick a compromise region that no one loves but everyone tolerates.
A single bad region choice can make a match unplayable for some, so the maximum ping across players matters more than the mean.
Practical concerns
- Region pools must have capacity, or the matchmaker falls back to a nearby region.
- A player far from all regions is paired with locals when possible to avoid stranding them.
- Anycast or a routing backbone can shave latency between the player and the chosen edge.
Key idea
Regional selection routes each match to the data center that minimizes the worst case player ping, since distance dominates realtime latency.