Invisible runner rule
（重定向自Invisible runner）
An invisible runner, or ghost runner, is a device used in baseball-style games, including softball, stickball, and kickball, when a team has fewer than four players. Used primarily in schoolyard games, the rule is called into action when a live runner on base is next in line to bat. The specifics of the rule vary regionally, and are often negotiated prior to the start of the game.