That is, a content first, content focused UX.
Whilst I wouldn't consider the majority of Windows 8, even 8.1, "Metro", and whilst Metro design was forcibly ripped from Windows 10 mobile, Windows Phone, and to a mild degree, Windows 8.1, brilliantly applied this form of UX, only to abandon it all with 10 and never look back.
Vertical scrolling still existed too, as needed! By paginating content with horizontal scrolling, it meant each page could focus more on its own content, allowing it to also vertically scroll as need be, giving amply more real estate to work with.
A lot of design concepts behind Metro are only today slowly working their way back into modern operating systems, whilst Microsoft is ripping it out like a white woman with power tools the load bearing drywall between her kitchen and living room.
