Advance to Boardwalk is also a slot machine produced by WMS Gaming (the gambling branch of Williams the arcade game manufacturer). This is one of several slots based upon the Monopoly board game (WMS licensed the Monopoly name and characters). This is a sort of hybrid slot machine. It has mechanical reels, but it also has an LED screen that comes into play for the bonus games (most mechanical slots don't even have bonus games at all).
This is a 3 reel, single payline game. Every other space on the reels are blank (like most mechanical slots). It accepts up to 4 tokens per play (the first three increase the wager, while the fourth coin "buys" the possibility of the bonus round). The machine itself is of the semi-upright cocktail variety (low to ground, playing area at 45 degree angle). With a large Monopoly board and LED screen affixed to the top of the standard cabinet.
All of the symbols on the reels are ripped straight from Monopoly (the game pieces, Mr. Monopoly, etc). The bonus game is activated if you manage to get three visible Mr. Monopoly symbols (they don't actually have to line up on the payline, they can miss it by one position). (Note, you must play 4 coins, or else you don't get the bonus game at all).
The bonus game itself is a twist on the real game of Monopoly. Your little man moves around the Monopoly board, getting bonuses at every step. The bonus game ends after 6 trips around the board, or upon landing on Go to Jail or Luxury Tax (which happens more frequently than statistics would merit).
Most casinos do not have many of these machines. They are a little more expensive than other machines. Plus they have a non-standard cabinet (well it is a standard semi-upright cocktail, but it has a 4 foot tall game board tacked on to the top). This means that the casino can't just throw these games anywhere (they wouldn't match). They are usually found in small islands of 4 or 6 machines.
From the WMS Gaming website
Players will never forget the excitement of the Advance to Boardwalk game! This 3-reel spinning slot machine features a full-size MONOPOLY game board with all of the classic MONOPOLY elements. Our favorite little millionaire MR. MONOPOLY is back to guide players through familiar MONOPOLY game play with some new twists and turns on the way to Boardwalk! With 3 MR. MONOPOLY symbols in a scatter pay position, the player starts the bonus round on the famous ‘GO’ space.