It's not certain why Microsoft axed this design. If it was meant to become the Lumia 435, Microsoft may have decided that the eye-catching screen was too expensive for the intended price point. If not, though, it's trickier. Microsoft might have determined that it couldn't mass-manufacture the phone, that it didn't fit well into the overall product lineup, or that there wasn't much of a market for low-cost Windows phones that didn't quite sit at the lowest end of the spectrum.

Either way, it's hard not to see the handset as a lost opportunity -- Microsoft could have had a visually exciting yet affordable device, but passed on it in favor of far more pedestrian hardware. And in some ways, it helps explain why Microsoft's late-stage mobile strategy kept flailing to the point where the company effectively quit development. Simply put, few exciting phones reached the market -- whether it was due to technical issues or an excess of caution, Microsoft kept canceling bleeding-edge projects (like the fabled McLaren) that could have lured people away from Android and iOS. The all-screen phone wouldn't have turned around Microsoft's fortunes by itself, but it could have been part of a larger effort to reel you in with phone designs that had few if any equals.