Maybe you've been on safari or in prison for the last month and are entirely unaware of the Wii Fit. Here's what you need to know: Nintendo, using the kind of rarefied marketing genius that spawned both the "casual gaming" revolution and Gyromite, has produced an oblong, sensor-laden Balance Board and accompanying program that will soon transform your life into a Yoga-centric, Steve Jobs-style wet dream of good health and white plastic. This device turns all of the guilt, passive-aggression, and sexual awkwardness of having a personal trainer into a series of avatar-guided games and exercises. Also, it's a scale.

It's interesting that no one mentions the s-word when reviewing the Wii Fit, as it figures heavily into the gadget's actual use. Mere moments after booting the system up, a cooing, electronic voice entreated me to "step on" the balance board. I did. Moments later, after a brief pas de deux with an onscreen avatar in which I gave it my height and age and it gave me some diverting pseudo-science about the importance of good posture, the true nature of the device revealed itself to me. "You're overweight!" it chirped. People pay $90 for this?

In time, however, I discovered that the gizmo does have its charms. Along
with calling you fat, it offers a variety of yoga poses, strength exercises, aerobic activities, and "balance games" to help whip you into shape. And despite the inherent silliness of a grown man trying furiously to spin a virtual hula-hoop, they're all pretty fun. Many functions offer a red dot which you must keep inside of a yellow target area to do the activity right and then scores your success—giving even the most pedestrian of exercises a game-like feel. This is not always a good thing, though: my roommate was reduced to paroxysms of laughter when he found me solemnly working to up my rank on the Single Leg Extensions. "If I only had a camera," he said, "I could make it so you could never show your face publicly again." Thanks a lot, Wii Fit. Now I'm fat AND nerdy.