[Gamelift] Stop players from entering a game session

Question

I would like to stop players from entering a game session once a minimum number of players have joined. Here's an example:

- The maximum number of players that could be in a given game session is 50.
- The minimum number of required players to start a game session is 25. 
- Once the minimum of 25 players is reached, I would like to "close" the game session so that new players cannot join this game session

I know that in the matchmaking rule set, there is this logic:
```
    "teams" : [{
        "name": "allplayers",
        "maxPlayers" : 50,
        "minPlayers" : 25
    }],
```

However, with the above logic, players can still enter the game session after the 25 limit is reached. How can I "close" the game session once the 25 limit is reached? By "close", I mean that new players cannot join this running game session.

Thanks!

ShashankJ_AWS · Answer

Hi!

There are a couple of ways you could potentially do this.

Once the game session has started, you can invoke [UpdatePlayerSessionCreationPolicy](https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-server-sdk5-cpp-actions.html#integration-server-sdk5-cpp-updateplayersessioncreationpolicy) through the server SDK with a DENY_ALL policy. This prevents the game session from accepting new players

Alternatively if this decision is being made outside of the game server itself (for instance a backend client service): 
* You could call the [UpdateGameSession](https://docs.aws.amazon.com/gamelift/latest/apireference/API_UpdateGameSession.html#gamelift-UpdateGameSession-request-MaximumPlayerSessionCount) API with the required max player session count, to update the maximum number of players that can be connected simultaneously to the game session.
* You could call the [UpdateGameSession](https://docs.aws.amazon.com/gamelift/latest/apireference/API_UpdateGameSession.html#gamelift-UpdateGameSession-request-PlayerSessionCreationPolicy) API with a DENY_ALL player session creation policy. This will prevent the game session from accepting any new players.

Thanks!

[Gamelift] Stop players from entering a game session

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