The 3DS originally lacked 3D and tilt controls

Even though Nintendo has been experimenting with 3D for years, and working on the DS successor for years, the two ideas weren't always connected. Speaking to Famitsu, 3DS hardware producer Hideki Konno revealed that early versions of the hardware were designed without 3D in mind.

"I became involved with development starting in 2008, but at that time, it didn't have 3D visuals," Konno said. "From Nintendo's perspective, they've released [3D racing game for Famicom] 3D Hot Rally and the Virtual Boy; they've had a history of experimenting with 3D visuals." With the advent of glasses-free screens, Nintendo decided this would be a good time to try again.

The same is true of the gyroscopic motion sensor. It was added just before E3. " The boat had really left the port by that point -- the hardware team had the final specs and just had to work it all out," Konno told Famitsu. "Then, in the midst of that, Miyamoto said 'This isn't enough; we can really change things if there's a gyro sensor in there.'" After playing with a prototype gyro-enhanced DS, Konno agreed. "We had a prototype for the sensor already, so we got everyone together to try it out, and the conclusion we came up with was 'Well, if we can do things this fun with it, I guess we've got no choice.'"

http://www.joystiq.com/2011/02/23/th...tilt-controls/