If you want that particular dark and broody theme, you will have to tinker around with the Windows Registry setting a little bit. So the statutory warning goes that if you are not aware of registry settings, kindly dont touch them. Tinkering the settings can be potentially dangerous and it is always better to take a backup of your data on external storage. Now that we have done with the warning part, tinkering a little bit with the Windows 10 registry lets you can unlock a whole new look for the operating system, taking Windows 10 to the dark side. It brings to the desktop version of Windows 10 a theme option reminiscent of Windows Phone. To start the hack head to the Registry Editor: just hit the Windows key, type regedit and press Enter. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ Themes\Personalize. You might find that the Personalize key doesn’t yet exist, so you may need to add it manually. Now create a new DWORD Value called SystemUsesLightTheme and assign it a value of 0. That’s it! Microsoft has not disclosed whether this is an Easter Egg in its new OS and whether this hack will be available in the final build of Windows 10. Till then you can enjoy the dark side of Windows 10. May the force be with your! Resource : Beta News. Build 10051 of Windows 10 Technical Preview — which leaked online in the last few days — has a hidden dark theme. If you have grabbed a copy of this particular build, you’ll have noticed that there are a few tweaks here and there such as a resizable Start menu and a redesigned system clock.