Childhood toys and stereotypical childhood games often illustrate the childlike approach you take to many relationships. To understand the marble dream, think about how well you play and how high the stakes are in the dream.
To dream of a game of marbles, or many other childhood pastimes, can mean an attempt to return to innocence. A key element is who is playing with you.
Are you playing with childhood friends, or with someone you've only known as an adult?
Does the game feel like a fun activity, or is it a competitive challenge?