There’s a great episode of the podcast 99% Invisible about The Landlord’s Game, which goes into more detail. Magie wrote two sets of rules for the game, one based on Georgism, the other on capitalism. The intention was that players would try both — even switching during a game — to see how Georgism could benefit everyone.
You can guess which version survived as Monopoly.
She didn’t sell her patent direct to Parker Brothers, though; the Landlord’s Game was heavily plagiarised, with localised versions appearing in many American cities. A Quaker version in Atlantic City was turned into the original Monopoly by Charles Darrow, who sold it to Parker Brothers. They later discovered Magie had invented it and bought her patent for $500.