You might wonder what it's like exercising with nothing.

Your Shape: Fitness Evolved from developer Ubisoft taps into the aerobics/yoga methods of ditching your extra fat cells (probably collected while playing video games), minus the rhythmic beats of aerobics and the quiet meditations of yoga. Instead, it takes the smart approach of catering directly to the people most likely to give it a whirl. Your Shape turns exercise into a game. A game, I hasten to add, that you want to win.

The Men's Warehouse could really use one of these.

A few people expressed skepticism when I put Your Shape: Fitness Evolved over Child of Eden as Microsoft Kinect's killer app. Not really a fair comparison, I admit, given one's a nearly finished game and the other still has months of refinements left. But in my limited time with Your Shape, I noted several top-tier prerequisites...stunning graphics, destructable environments, classic- puzzle-game elements, and a definite wow factor.

Hey, I wouldn't believe me, either. So here's a video of me playing Your Shape.

I'm going through one of Your Shape's exercise routines at last week's Ubisoft Kinect Event in downtown San Francisco. An Ubisoft PR guy kindly shot this using my iPhone, so apologies for the poor resolution (and thanks, Ubisoft PR guy).

The name of this game is Stack 'Em Up, but I'll just call it Human Tetris. I'm holding a virtual board in my hands as blocks drop. Hold it overhead and the blocks leisurely float down; lower it to waist-height and they fall like lead-covered rocks. Stack 'em high for more points, but you only bank that score when you tip the load into an open pit on either side. These pits, naturally, open and close at random.

A few explanations: Kinect put a virtual me into the Your Shape playing field -- right down to the sunglasses tucked into my collar -- moving in real time (you can also catch glimpses of Kinect grabbing people walking behind me). So I'm in control of what's happening, both inside and outside the game. That's not a pinball flipper action, either. I'm controlling the exact depth and speed every time I tilt the board. It's actually a bit challenging to keep it completely level. I got skilled enough to flip a block off one end of my board and catch it on the opposite end.

Lateral movement, on the other hand, feels like it's barely implemented into the move set. Quite an oversight, given the whole "stack 'em" motif. Still, this isn't really Human Tetris...it's a yoga routine, hidden inside a fun game.

Breaking blocks = video game.

Stack 'Em Up and a block-smashing game (requiring rapid torso twists) sold me on the approach. I'm sure Your Shape boasts a pure, no-frills, high-impact exercise routine somewhere in its game set, but I hope it's as well camouflaged as these two were. When I work out, I like a distraction to take my mind off whatever grueling torture I'm putting my body through. Usually, that's a fast-paced film or TV show. Couching my physical movements as components of a game works even better, because I'm actively participating. Moreover, I want to beat the game, so I'll always try harder. Kind of the point of exercise, really.

And for the Achievement whores in the audience, the bulk of Your Shape's points revolve around how many calories you've burned. Though without biometrics, Your Shape will guess that number. Add weights to your session and it's bound to guess wrong.

A bit more creepy is the online element. You can challenge friends and frenemies alike to hit targeted goals, which I can see going very badly in the competitive hands of a few hardcore health fanatics. If picking on your amigos doesn't satisfy your lust for fitness domination, Ubisoft plans to institute regional challenges as well...say, Chicago vs. New York, first city to lose 100,000 calories wins. Hey, it's not like they don't already fight over who has the best pizza.

Regardless, disguising exercise as a game makes the workout faster, less painful, more fun...and more likely to become a cherished routine than a forced burden. What I've seen of Your Shape takes that idea further than either Wii Fit or EA Sports Active -- the current exercise game champs -- have attempted, and I hope it goes further still. If anything, that's how Kinect can move outside the narrow Xbox 360 install base and into the mainstream: by making even the most rigorous experiences a pure joy.