|Pokki on Windows 8 with the App Store running in the background|
No, there's no "unofficial" way to get the Start Menu back. It's not there at all so there's nothing to "get back". If that's what you're after, then you can stop wasting your time here.
Previously, I've posted about Classic Shell as a way to get back your Start Menu. It works but it never hurts to have another option around. ViStart was also available if you didn't like Classic Shell.
So here's Pokki with a much more modernised Start Menu. Pokki even works on Windows XP/7 as a "App Store" providing shortcuts to your favorite apps, search, app downloads and much more. On Windows 8, it also acts as a Start Menu replacement.
Your programs are available in All Apps while Control Panel applets are under Control Panel. Shutdown is available right at the bottom of the menu just similar to Windows 7.
If you really want/need to access the new Start Screen, then the Windows button beside the Shutdown button brings you there. Once installed, Pokki takes over the Window key on your keyboard so you don't accidentally go to the Start Screen anymore. If you're on the Start Screen already it doesn't work though.
Pokki's default settings work fine but if you want to customize it further then the drop down menu beside the search box has a link to Pokki's settings.
Head over to Pokki's website to download it.
ViStart: An alternative Windows Start Menu
Classic Shell: Take back your Windows Start Menu