"Microsoft would argue that you don't need any other devices, since theoretically the Xbox One can fill the role of almost all of them, but that promise might not be borne out in the real world," says Sakey.
Sony also has a motion-sensor camera device, called the Eye, but it's optional hardware that Sony isn't making a big deal about. It's expected to go on sale for $59 when the PlayStation 4 launches, according to Kotaku.
When to buy
If you're looking for price drops, you could be in for a long wait. The 360 didn't need to offer a price cut because of its accessible $300 entry-point model. Microsoft maintained the 360's launch price for a record-setting 20 months before a price cut, according to a 2007 CNN article. Conversely, Sony cut the price of its much more expensive $600 entry-point PlayStation 3 by $100 seven and a half months after launch, according to a company press release.