The "Tony Hawk's" series was originally developed as a classic arcade game. The goal of most modes of the game is to achieve a high score. To do this, the player has to successfully perform and combine aerials, flips, grinds, lips, and manuals, with successful executions adding to the player's score. The point value of the trick is based on time maintained, degrees rotated, number of tricks performed in sequence, performing tricks on specific landmarks on the map, and the number of times the tricks have been used. Successful tricks also add to the player's special meter, which, once full, allows for the execution of special tricks which are worth a great deal more than normal tricks. Bails (falling off the skateboard due to poor landing) cause no points to be awarded for the attempted trick and reset the special bar to empty. The controls of the game developed further the more the series progressed. While the original "Tony Hawk's Pro Skater" featured a fairly limited set of moves, later entries allowed the player to switch between moves during the same grind or manual sequence, perform transfers, hold on to and drive various vehicles, walk on foot and scale walls, slowing time, or performing more advanced tricks by pressing buttons repeatedly, for example a double or triple kickflip instead of a normal one. Later entries, such as "American Wasteland", allowed the player to also use a BMX, whereas "Motion" and "" featured snowboarding.