If you own a smartphone, it's pretty much a certainty that you're running on Android or iOS. Sure, a handful of sporadic alternatives might exist but when it comes to mobile operating systems, it's a two-horse race: Google or Apple.
But it wasn't always like that, at one point in time Microsoft's Windows Mobile OS brought a unique "Metro" tiled interface to the smartphone that I will unashamedly say is one of my favorite phone UI designs to date (and I don't care how alone I am in that judgment).
