Sitting around a campfire last summer, we decided the world really needed a gigantic outdoor version of Pong that could turn up in the most unlikely places. Thus, King Pong was born. (For those born after 1972, Pong was the first popular video game — just two moving paddles and a bouncing ball.)

The pieces we needed to put together were a netbook computer running a custom version of Pong, a video projector, a portable power supply, and two game controllers. The first job was to write a clone of the original Pong game in Visual Basic. For the projector, we searched for the most lumens per dollar and chose a Dell 1510X. To power it all, we got an old marine battery and a power inverter.

For the controllers, we wanted something that would grab attention and be easily recognizable. Ideally it would be wireless, as we learned from our tests that wires in the dark were a constant menace. So we mounted a bicycle wheel on a cheapo camera tripod using a standard L-bracket.

The sensor that detects the wheel’s motion is a simple single-pole double-throw (SPDT) switch mounted so that it sticks out between the spokes. As you spin the wheel in either direction, one of the pairs of contacts toggles on/off. Finally, we used a pair of XBee wireless modules, one for each controller, to send the signal back to the netbook (aka the Pongputer).

With this setup, we have a portable system that can be thrown in the back seat of a car, set up anywhere in less than five minutes, and project a 100-foot-high Pong screen on nearly any surface. King Pong has filled an enormous sand dune on Cape Cod; it’s been projected from the top of a bridge across a river onto trees in a forest; it’s been played on the surface of a pond. You never know where King Pong might turn up next.