Remember when Microsoft pulled a surprise out the bag during its recent Windows 10 press event in the shape of the HoloLens? Well, it turns out it wasn't a surprise at all. Pocket-lint even covered it June 2012.
A 52 page leaked document that hit the internet that summer all but detailed the augmented reality glasses as a part of the company's next generation gaming ambitions. The same .pdf file, while was subject of multiple takedown orders by Microsoft after several sites posted it for download, thereby validating its authenticity, also showed elements of what turned out to be the Xbox One, second generation Kinect, and SmartGlass.
Indeed, the document was dated 2010, so the company's plans were even more ambitious at the time the roadmap was put together. Some of the dates didn't pan out, including HoloLens (called Project Fortaleza at the time) which was suggested for a 2013 release, but the actual product is not a million miles removed from the device in the artists impressions printed.
Another thing that changed in before an actual release was the new Xbox console's name, from 720 to One, but on the whole the clues were all there. Cortana also featured in some form, although strictly as a big screen voice-control concept.