I would change Free Parking to Paid Parking. This will help to discourage the house rule where people collect a pot of all paid fines when they land on that space. That way of playing arbitrarily lengthens the game, making for a bad play experience.

As a flat tax it will hurt the players who are further behind, bringing the game to a close faster, one of the primary complaints with this game. From a thematic point of view, it will make perfect sense to our increasingly urban population,

I would keep the rule that states "If you do not wish to buy the property, the Bank sells it at through an auction to the highest bidder."

The only problem with this rule is that most people don't seem to know it. To encourage people to learn the rule, I would add a new space to the center of the board titled "Auction House", to make people ask the quesion, "what is that?" and look it up. The rule could even be written directly on the board.

Nils