Over the weekend, an unnamed Microsoft partner leaked an early build of the Windows Blue project, revealing new features that could become part of Windows 8 before the end of the year.

Some users have already posted their impressions of the new operating system, along with screenshots. News of the leak was first noticed on a Polish forum dedicated to all things Windows.

Judging by the unfinished build, Windows Blue will offer desktop users new tile sizes, extended customisation options and more settings available directly from the “Start screen”.

The update confirms Microsoft’s commitment to the Start screen as the default navigation tool in Windows, and includes the upcoming Internet Explorer 11 browser.

Since the existence of the project was accidentally revealed in February, Windows Blue has given birth to plenty of wild rumours. Microsoft has made a heroic effort to keep the details secret, as no one was sure what the weirdly named software product actually was, until now.

During the weekend, an unnamed Microsoft partner leaked Build 9364 of Windows Blue online, and it is now doing the rounds on the Web. It turns out the project is indeed an update for Windows 8, but there are no details on whether a similar update will be made available for Windows Phone 8, as the earlier rumours suggested.

The changes begin with the Start screen: according to Build 9364, Windows Blue will offer desktop users more tile sizes – smaller tiles taking up a quarter of a standard tile, as well as bigger ones which combine four standard-sized tiles into one. There are also other customisation options for the start screen, like the ability to set your own background and choose highlight colours, right from the “Charms” bar.