Setting this to true will allow players with access to a certain game the ability to challenge players that do not have access to the game themselves.
Example: Player1 has access to TicTacToe. Player2 does not have access to TicTacToe. Player1 can challenge Player2 in the game and Player2 can accept the challenge even though they do not have permission to start such a challenge themselves.
The setting is added automatically to the settings.yml file and is by default false.