Microsoft began work in earnest on the Xbox One in late 2010, the company explained in a new video posted to the Xbox Wire.
"We started back in 2010; late 2010. And got the team together and really had fun," Sr. Principal Creative Director at Xbox Carl Ledbetter said. "At the beginning, we created a number of concepts and we started really refining those ideas."
By comparison, PlayStation 4 lead system architect Mark Cerny said Sony began "thinking about" its next-generation platform in 2007. It isn't clear, though, when the company began actual work on the system.
Elsewhere in the video, senior Xbox industrial designer Scott Dallmeyer revealed Microsoft created hundreds of different concepts that eventually evolved in the Xbox One.