Microsoft's augmented reality appendix widely known as the Kinect is no longer available for purchase. The device has been discontinued but parts such as its sensors will still be used for Microsoft's HoloLens AR headset.
The Kinect had a troubled existence in the gaming landscape. It promised to fulfil some of our more science fictiony dreams and hopes for games as a medium, while at the same time making a lot of people concerned over surveillance and privacy.
The device's potential for gaming has never really been fully exploited, partly due to lack of interest from developers and partly because the tech was never quite reliable enough to be considered a valid alternative to more traditional joypad input. Few games were based entirely around the system, and those were usually of the more gimmicky variety, while games that made at least partial use of the device were few and far between.
Microsoft's own store now lists the Kinect as out of stock. A lot of that stock was probably put into customers living rooms, usually under the sofa, through the practice of bundling the device with the Xbox One. The Kinect was later taken off the back of Xbox One's struggling sales in order to drive the price down. Later iterations, the Xbox One S and X don't even have a dedicated port for the motion tracking apparatus.
Roughly 35 million Kinect units are still out in the wild, and Microsoft still intends to offer support for these, but it is now clear that the technology was and is a bit of a dead end as far as both customers and developers are concerned.
If you are interested in what the project contributed to the future of Microsoft's product line-up, have a look at HoloLens. It works with repurposed Kinect sensors.