Windows Vista build 5221 (vbl ux dev checkin gamesux)

Windows Vista build 5221 (vbl_ux_dev_checkin_gamesux) is a pre-Beta 2 build of Windows Vista. This build was used as concept art in one of Microsoft's presentations and demos at PDC 2005. A screenshot of this build was accidentally posted to Microsoft's website where WinBeta.pl archived it before it was taken down.

This is the earliest known build to include the start menu used in build 5252 onwards, alongside with the start orb and darker taskbar seen in other  builds.

Unfortunately, the demo that originally showed off this build was taken down and no archived versions exist at this time.