Pretty sure he got it from the instructions itself. It's been all over the gaming media that you need a huge amount of space to make it work properly citing actual Microsoft documentation. It's not exactly contested terrain.
Here you go:
You know what the biggest problem with Kinect is though? The lack of super peripherals to spend more money on. I mean, look at Sony's new gun attachment for Move.
Wtf.
No, but seriously, the problem with Kinect is the lack of core content and the limitations of controllerless gaming. And the price.
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