The real-estate game of Monopoly is the all-time best-seller among board games. Since it was introduced in 1935 and up through 1974, more than 80,000,000 sets have been sold!
The company that manufactures the game, Parker Brothers, prints $18,500,000,000,000 (181/4 trillion dollars) worth of play money for Monopoly every year. This is more than the total of real money printed in the entire world.
The game was created by Charles Darrow, an unemployed inventor, who named the streets after those in Atlantic City, New Jersey, where he used to spend his vacations.
The popularity of this game has created yearly National Monopoly Championships, in which the winner takes home the Charles Darrow Award, named after the inventor.
The record for the longest Monopoly game played by four players was set from December 26, 1974 to January 5, 1975, for a total of 264 hours!
Although, monopoly is by far the most successful franchised game it is still a long way behind the traditional board games.
Both Go and Xianqi have very large number of players in the far east. I suspect that there have been more chess sets sold than monopoly since 1935 too.