De Pong Game is an interactive gaming installation — designed by Arjan Westerdiep — that explores augmented reality “by using and interacting with urban architectures [buildings] as background for the game.” Clip after the jump.
Thus the game is projected on a building and the limits of that building are becoming the limits of the game area. The ball projected on the building bounces along the limits of the walls. The software is also using the windows as an obstacles for the game
So the ball is limited to frame of the building. As you touch the ball with the slider, its speed increases and because the ball bounces on all the obstacles of the architecture it becomes more and more difficult to play