public static function onRandomGameUnit( &$random_games, &$custom_fallback ) { ... }

$wgHooks['RandomGameUnit'][] = 'MyExtensionHooks::onRandomGameUnit';

The RandomGameUnit hook, provided by the extension with the same name, allows adding a new type of random casual game that RandomGameUnit can pick, in addition to the three "built-in" types of games: polls (provided by Extension:PollNY), picture games (provided by Extension:PictureGame) and quizzes (provided by Extension:QuizGame).

It is also theoretically possible for a hook subscriber to remove items from the $random_games array or even set it to a blank array, which would then force the <randomgameunit> tag to return an empty string.

The only extension that ever sorta used this hook is the ArmchairGM-specific PickGame extension (directory name "SportsGames"). This is basically how it used it:

	public static function onRandomGameUnit( &$random_games, &$custom_fallback ) {
		$random_games[] = 'custom';
		$custom_fallback = 'PickGameUnit::displayPickGameUnit';

		return true;
	}

The callback method (PickGameUnit::displayPickGameUnit in this example) would then handle the logic of picking an appropriately random "custom" game unit for the current user and return its HTML.