Come-into-my-castle is a game played by multiple individuals, usually children. The game is designed to teach noble children about courtesy, heraldry, and the friends and enemies of their house. Usually only nobles play the game, as commoners do not have castles.
As a child, Arya Stark played come-into-my-castle, monsters-and-maidens, and hide-the-treasure with the children of the people of Winterfell. She also played come-into-my-castle and monsters-and-maidens amongst the stone kings in the crypt of Winterfell.