The game is basically controlled by the keyboard. Therefore we need to bind the corresponding event handlers to the document. We are just interested in a few keys, which can be pressed or released. Since we need to monitor each key’s state we just extend the object keys with the corresponding properties (like left for the left key, right for the right key and so on).
Mario is portrayed as a short, plump, mustachioed Italian plumber from Brooklyn who resides in the Mushroom Kingdom. He repeatedly has the mission to rescue Princess Peach, from the villain Bowser and prevent his various plans to destroy and dominate the kingdom. Mario also has other enemies or rivals, including Donkey Kong and Wario.