Allow requirements to relax over time

Expansions allow you to relax rule criteria over time when FlexMatch can't find a match. This feature ensures that FlexMatch makes a best available when it can't make a perfect match. By relaxing your rules with an expansion, you gradually expand the pool of players that are an acceptable match.

Expansions start when the age of the newest ticket in the incomplete match matches an expansion wait time. When FlexMatch adds a new ticket to the match, the expansion wait time clock may be reset. You can customize how expansions start in the algorithm section of the rule set.

Here's an example of an expansion that gradually increases the minimum skill level required for the match. The rule set uses a distance rule statement, named SkillDelta to require that all players in a match be within 5 skill levels of each other. If no new matches are made for fifteen seconds, this expansion looks for a skill level difference of 10, and then ten seconds later looks for a difference of 20.

"expansions": [{
        "target": "rules[SkillDelta].maxDistance",
        "steps": [{
            "waitTimeSeconds": 15,
            "value": 10
        }, {
            "waitTimeSeconds": 25,
            "value": 20
        }]
    }]

With matchmakers that have automatic backfill enabled, don't relax your player count requirements too quickly. It takes a few seconds for the new game session to start up and begin automatic backfill. A better approach is to start your expansion after automatic backfill tends to kicks in for your games. Expansion timing varies depending on your team composition, so do testing to find the best expansion strategy for your game.