For such a simple device, the Wii Nunchuk offers amazing features. Much of that simplicity is deceptive, though, since this add-on Wii game controller has far more to offer than its simple appearance would suggest.
The Wii Nunchuk connects to the Wii Remote via a cord that provides both electrical power and coordination between the two devices. Nyko makes a wireless version for those who want to eliminate the cord. So, the Nunchuk needs no batteries unlike the Wiimote, which takes 2-AA's. It also provides a feedback loop to the Wiimote and the console, increasing realism and control.
Boxing, for example, takes on an added dimension thanks to the Nunchuk. Gamers can jab with the left (the Nunchuk) and fire off a roundhouse punch with the right (the Wii Remote). In a first-person shooter, the Nunchuk lets you control the basic movements while you fire with the Wiimote.
The Nunchuk (named after the Japanese martial arts weapon) can do that because it contains much of the technology of the Remote and some extras. It houses the same type of three-axis motion sensors so you can shift left and right, up and down, forward and backward, and perform rotations (a combination of the three). In addition, it adds an analog stick and two buttons similar to traditional game controllers.
The Nunchuk thus becomes more than the sum of its parts. Working alone, it gives you added realism and a wider range of motions by the combination of traditional gaming controls and Wiimote-style control. Working in conjunction with the Wii Remote which works with the sensor bar and receptors in the console, it provides a new level of gaming.
Most players (like most people) are right-handed. So, they'll hold the Wiimote in the right and the Nunchuk in the left. But the devices are designed to be ambidextrous, so you can easily switch them without a loss of control. If you happen to be left handed, or just learned to play computer games that way, you'll enjoy the same full experience whichever way you choose.
You can even use the extra ports on the console to plug in more than one Nunchuk (and more controllers, like the Classic Controller or a GameCube controller). That permits a huge variation in your style of play for single-player games, and even more fun for multiple-player games. In either scenario, you can use the analog stick to increase character movement while you use the Remote to throw a football, aim a rifle, or perform hundreds of other moves with increased realism.
The Nunchuk is supplied but not required, though. In fact there are many games, especially older ones from the GameCube (and earlier) era that don't take advantage of the added flexibility. Even in more contemporary games where the Nunchuk can be used, it is often not essential.
Like any new gaming device, there is a learning curve involved, but the free Wii Sports available with the system provides plenty of fun opportunities right out of the box for getting used to the Nunchuk. Once you do, you'll rarely want to be without it. The combined pair makes gaming the next best thing to virtual reality.