Elizabeth Maggie
In 1903, the Landlords Game was created by Elizabeth Maggie to help teach a single tax theory. It was patented in 1904 and produced in 1906. However, the patent expired in 1921, which opened the way for other versions with various rule changes.
Dan Layman
The game Finance, which was eerily similar to the Landlords Game, was sold to Electronic Laboratories in 1932 by Dan Layman.
Ruth Hoskins and Charles Todd
Ruth Hoskins moved to Atlantic City shortly after learning about the game Finance from Dan Layman. Once there she taught the game, which was slightly different than Finance and called Auction Monopoly since no property had a fixed price, to Charles Todd.
Charles Darrow
Charles and Esther Darrow, who were friends of Charles Todd, learned to play Auction Monopoly during a visit to Todd's home. Shortly after this, Darrow patented an Auction Monopoly game and began producing them, but was unable to keep up with production, which resulted in him contacting Milton Bradley and Parker Brothers concerning the game. Both companies rejected the idea due to design flaws.
Controversy
Parker Brothers ultimately decided to purchase the Auction Monopoly game from Darrow in 1935, which sparked a big controversy, as the game technically wasn't Darrow's to sell. This meant that the Parker Brothers had to buy out smaller versions of the game, including Hoskin's version, and one large version of it for $10,000, which was a considerable sum during the Depression.
Patent Granted
In 1935, Parker Brothers changed up the game slightly, which they called Fortune. Less than 5,000 of these were produced before they were able to secure a patent for the game that we know today as Monopoly.