Simply put: it's Windows 8 in a browser.
Check it out yourself - Windows Web 8 Live link.
Online design mockup of the Microsoft Windows 8. Coded using HTML5, CSS3, SASS built-in functions and jQuery to create a perfect pixel web mockup of the Microsoft Windows 8 Operating System. The project features boot screen, login screen, desktop, start menu, apps and a complete real-time experience of Windows 8 OS.