There is a feature in Windows for a long time that allows system administrators to lock down the device and allow the user to access only a single application. This feature makes Windows a perfect choice for kiosk terminals. Windows 8.1 contains a more enhanced version of this feature originally called Kiosk Mode, now renamed to Assigned Access, that allows sysadmins to enable a single Windows Store application experience on the device. This is how this feature looked in the leaked builds before the preview:
Don’t look for this feature in the official preview, it will be available only in the final product.