Parker Bros. is a game manufacturer and brand since 1883. The company has published more than 1800 games; among their best known products are Monopoly, Cluedo (licensed from the British publisher and known as Clue in North America), Risk, Trivial Pursuit, Ouija boards, Aggravation and Probe. Parker Brothers is currently a subsidiary of Hasbro.
One day the teenaged Parker boys were playing one of the games meant to teach a moral lesson, Everlasting, and felt bored. George decided to modify the game by adding lettered cards and a borrowing rule and came up with Banking where the new objective was to become the richest player by winning speculations. A speculation began when a lettered card was played and ended when another card of the same letter was played. The winner was the one who eventually claimed all the cards. To avoid this, players could borrow cards from the bank at 10% interest (borrow ten cards, pay eleven). Partnerships could be formed and profits shared. Banks were very popular during this period and seen as the way to have a secure fortune as opposed to the unregulated stock and bond exchanges where greed and ruin was documented in the papers every day.
Office Boy Game - 1889: The country was in love with the novels of Horatio Alger in which young men rose from obscurity to conquer all, just by being good. This game attempted to adapt the Mansion of Happiness setup to cash in on the phenomenon by positing players as office boys who travel around a spiral track that uses hexagonal shaped spaces. Some spaces direct a piece to advance or go back. The first player to reach the center space becomes Head of the Firm and wins the game.
George and his friends liked the game so much that he courageously had 500 copies printed up and successfully peddled them to Massachusetts area retailers, eventually selling all but 12 copies, making a profit of $100. And so it all started.
What's it worth? Take a look at this Parker Brothers price guide: sold listings for a value indication.