David Imel / Android Authority TL;DR An unreleased prototype of Microsoft’s dual-screen foldable phone, Surface Duo, was recently found listed online for sale. While Surface Duo ran on Android, the leaked prototype runs an unreleased version of the Windows Phone interface. Microsoft envisoned this as an intermediate between a regular phone and a Windows PC, but never realized due to the decline in Windows Phone’s popularity. Microsoft persistently dabbled with mobile phones for almost the entirety of the 2010s — and for a couple of years after that, too. While its Windows Phone operating system garnered both appreciation and criticism, a project that was critiqued mainly was its category of folding devices, known as the Surface Duo. The Surface Duo was a folding phone, but unlike the Galaxy Z Fold devices, it came with two separate screens for running multiple applications side-by-side. The first generation (yes, there were more than one!) Surface Duo felt like a prototype and offered a jarring software experience full of bugs. The second generation came with slight upgrades, but felt outmoded by true foldables that were starting to take over the market. A third generation aimed to solve that, but it was cancelled before it could take form. Would you buy a Suface Duo if it ran Windows? 37 votes Yes, I used Windows Phone and loved it 46 % I might be willing to try 32 % No, the hardware felt too clunky 3 % No, Windows belongs on big screens 11 % Any other (let us know in the comments below) 8 % Notably, both of the Surface Duo models that existed ran Android. But there was a third — actually, the very first — prototype designed to run Windows that never came to be. A few Windows-based Surface Duo prototypes were recently listed for sale on Goofish, a Chinese marketplace for second-hand products, and spotted by Windows Central. The said prototypes of the Microsoft Surface Duo apparently run a special version of the now-defunct Windows Phone interface with tiles for applications on one screen and tiles with functionality similar to Android’s quick settings on the other. Windows Central proposes this prototype runs on “Andromeda OS,” an operating system which was envisoned by Microsoft to work on pocket-sized alternatives to Windows PCs. However, it never truly saw the light of day, as Microsoft instead adopted Android as the more fitting OS for the Surface Duo. GooFish In the later years, Microsoft was also expected to bring a Windows-inspired skin to run atop the Android interface, but that was never delivered, as Microsoft decided to give up its plans. The model listed on the platform has a few noticeable differences from the first commercial version of Surface Duo. It has a monochrome camera to capture 3D footage for Holo Lens devices, a metallic frame, and a mechanism to charge the stylus wirelessly. The Surface Duo 1 lacked all of these features (including the camera!), and the likely reason was to reduce the weight of the hardware. GooFish However, there are various observable similarities, such as the 360-degree hinge that allows rotating screens both inwards and out, a glaring Windows logo on one of the panels, a squarish design, and thick bezels above and below the two screens. One of the many prototypes listed on GooFish also features a narrower shell as compared to the actual Surface Duo, suggesting it was one of the many iterations Microsoft experimented with before finalizing one. GooFish The Surface Duo, especially one with a truly folding display, could have carved a new category of products that would sit between phones and PCs. But Microsoft decided to axe the project entirely in 2023, a decision that CEO Satya Nadella later lamented in an interview later that year. Currently, the prototype is listed for a staggering price of ¥98,999 (roughly $13,730). At this price, it feels like a collector’s edition and less like a product anyone would (willingly) buy — if they can get themselves to trust a less popular peer-to-peer selling platform. Follow