LOS ANGELES – Nintendo's new 3DS hardware is, in a word, unbelievable.

The company didn't talk about how its stunning technology works during Tuesday's brief demo for members of the press. But work it does: Without using special glasses, you can see a deep, rich 3-D display on the top screen of the new Nintendo 3DS portable.

__NINTENDO 3DS FEATURES:__Twin screens

Top is 3.5-inch 3-D display; bottom is touch panel.

Technology

Possibly parallel barrier LCD.

Cameras

Twin cameras on back for 3-D photography.

Gyro and motion sensors

Should introduce new types of movement-based gameplay.

The short, interactive demos Nintendo showed after its conference Monday morning included peeks at new Metal Gear Solid and Resident Evil games.

A slider on the right-hand side of the screen lets you adjust how "deep" the 3-D effect looks. You can take it all the way down to zero and see the games in 2-D, or you can crank it up.

I found about 80 percent intensity was just right for my eyes. When I had the 3-D effect all the way up, I couldn't quite focus on the scene in front of me. (It'll likely be different depending on the individual player.)

Konami is producing a version of its hit PlayStation 3 game Metal Gear Solid 3: Snake Eater for the Nintendo 3DS. The demo showed a first-person sequence in which all sorts of crazy things happened to hero Solid Snake, all playing with the 3-D effect: Knives flew at the camera, and a massive alligator snapped its long jaws.

In the second half of the demo, Snake walked across a bridge and avoided enemies in his usual style. While we couldn't control him, we could use the analog stick on the 3DS to adjust the camera and see the 3-D scene from many different angles.

That analog stick on the side of the unit, by the way, is pretty fantastic. In sharp contrast to the Sony PSP's tiny analog nub, it's a wide, convex pad that lets your thumb sit comfortably inside as you control the game. A standard digital control pad sits below it.

The back of the Nintendo 3DS looks ordinary enough.

Photo: Jim Merithew/Wired.com

Capcom's Resident Evil demo was a bit less involved. It was just a brief cinematic scene showing a few characters talking about something. (Probably zombies: I was too busy checking out the 3-D effects to pay attention to what they were saying.)

The graphics, which are much more advanced than you'd expect from Nintendo, left me pretty much in disbelief. They're on a level with Sony's PSP, probably even a little better than that. But the eye-popping 3-D effect makes everything that much richer.

The other demo Nintendo showed wasn't a game at all. It was a collection of 3-D scenes from various Nintendo games. Each tableau, like a shoebox diorama, was animated, and we could move the camera around to better see how the 3-D effect made the characters pop. Familiar faces from Mario, Zelda and Pikmin danced and played onscreen while we tilted the camera around.

You can only see the 3-D effect if you're looking at the 3DS screen straight on, although there's a good amount of fudge factor there – you can move the unit around quite a bit and still get the effect.

It's not as if you have to hold your hands in the exact perfect place. If you tilt the unit away from your face so it's almost at a 180-degree angle, you can still see the 3-D effect. If you tilt it left and right, you'll lose the effect and the picture will go smudgy, like what happens when you remove your glasses during a 3-D movie.

Nintendo will surely have actual games on the show floor when the E3 Expo opens later Tuesday. But this quick look made it easy to understand that the new 3DS really does do full-on 3-D without glasses.

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