Matchmaking refers to the way players are distributed in battles. Matchmaking works on basis of various different aspects, being:
- Aircraft tier
- Aircraft type (and model)
- Amount of human/ bot players
Amount of players
Normally, matchmaking will try to fill both teams of 12 players evenly. Due to the somewhat thin playerbase, this currently involves filling part of the 12 players on each team with bot players. Both players should have an equal amount or at most 1 difference in the amount of bots (respectively human players). In addition, aircraft will be distributed such that the amount of aircraft from each tier are matched. The only way this may be disturbed is by flights, other than that the matchmaker will try to mirror both teams. Normally, an aircraft can be put in battles with aircraft of its own tier and one tier above or below (again, flights can cause issues here).
Aircraft of a certain tier may face enemies of one tier higher or lower. They will never be in battle with aircraft of both one tier higher and one tier lower, as then the lower tier sees enemies of two tiers higher.
To keep the game balanced, the types of aircraft present should also be roughly equal. Bombers must be present at the exact same count, again only disturbed by flights, while the other types may have slightly varying numbers. Note that while bombers should also be of equal tier, this does not go for the other types: if both teams have three heavy fighters, one team may have different tiers than the other.
When two players fly together in a flight that is not of equal tier the matchmaker may become confused. This is because the matchmaker only determines one profile for the entire flight. This profile is the flight tier, which is always the highest occuring tier in the flight, and the type of this aircraft. The other player gets ignored and an opponent is selected "randomly" within allowed matchmaking. This can cause a flight with a down-tiered bomber not to face a bomber for instance.
Behind the scenes the servers keep track of how you get put into battles by a system called Karma. Karma means that each time you get put into a battle of your own tier along with lower tiers, you lose a point. Each time you go into a battle with higher tier aircraft, you gain a point. Normally this should level out randomly, but when you've played a lot of battles with higher tier aircraft in a row you'll end up with a high positive score. Once this score goes above a certain level (not sure of the level, I think 6) the matchmaker will force you into a battle with lower tiers. The Karma is now 5, so now you continue with random matchmaking until you go above the treshold again. This also goes the other way around: if you play a lot of tiered-down battles, you are sure to face higher tiers eventually.
Apart from aircraft types the matchmaker will normally mirror teams layouts with aircraft models pretty exactly aswell. This is mainly due to the fact that there are a lot of battles with a high number of bots. These bots simply get mirrored to each other and the human players, such that battles are as even as possible.