Windows 8 has been around for a year-and-a-half, but many developers choose to ignore it. The simple truth is that both Windows 8 desktop applications and Windows Store (Metro) apps for PCs and tablets are few and far between.To get an idea of the level of developer indifference to Windows 8, consider this: according to Microsoft, just 150,000 Windows Store applications for Windows 8 have been developed and are ready to download. That may seem a large number, but it's dwarfed by the more than 1 million tablet and smartphone apps in the Apple and Google stores.Ominously for Microsoft, the number of new applications being posted on the Windows Store appears to be declining rapidly. Nearly 20,000 new apps were submitted in June 2013, but this number crashed to less than 4,000 by the end of the year, according to the MetroStore Scanner website.The problem, according to Wes Miller, an analyst at Directions on Microsoft, is simply that developing for Windows 8 represents too much effort for very little possible return."It's amazing that developers build (Windows Store) apps given there's only a small customer base," Miller says. "If you are thinking about building an app, especially if you are a start-up, then iOS and Android is where the volume is \u2014 and then the labor you have put in to building the app is not transferable to building a Windows Store app."Consider Multi-platform Development, Microsoft SaysTim O'Brien, general manager for platform and applications at Microsoft, argues that that's not strictly the case. "There's an ecosystem of middleware vendors that gives developers the ability to write once and develop to many platforms," he points out.Many cater only to Android and iOS, ignoring Windows Store (and Windows Phone) completely, but some multi-platform development tools such as Xamarin and Apache Cordova (PhoneGap) let you output native apps for Windows platforms as well as iOS and Android. The Unity games development platform can also output Windows Store and Windows phone apps.One company that has developed Windows 8 apps is AirStrip, a software developer that makes medical monitoring applications. In the past, AirStrip offered iOS, Android and Blackberry apps to its physician customers; recently the company decided to offer a desktop version of its application to make it easier for medical staff in hospitals to enter information.AirStrip CEO Alan Portela decided to develop a Windows 8 application for touch-enabled PCs, which would work in the same ways as the existing touch-based iOS, Android and Blackberry mobile applications. He also decided to produce applications for Windows 8 tablets and Windows phones to go with it.This may seem to make little commercial sense given the tiny numbers of Windows tablet and phone users, until you understand the economics behind the decision. "Microsoft said, 'We will fund the effort,' and paid us a significant amount to do the port," Portela explains.\n[ Tips: How Cross-platform Tools Make Mobile Development Easier ]\n[ More: How to Support Mobile App Development in Your Organization ]\nThe end result: Hospitals that want to use the system have to upgrade to Windows 8 computers with touchscreens, while physicians can still use their choice of iOS, Android and Blackberry devices \u2014 and, now, Windows mobile devices, should they wish to.\nPaying Windows 8 Developers Potential 'Bottomless Pit' for Microsoft\nMicrosoft paying for the development of Windows Store apps is certainly one way to boost the Windows 8 app ecosystem until it reaches a critical mass \u2014 but this approach is not without its dangers, Miller warns. It doesn't matter what you pay a company to build an app for your platform if customer's won't use it and the app gets abandoned, he says. "For Microsoft, this could be throwing money into a bottomless pit."\n\nLast spring, Microsoft tried a slightly different strategy, offering developers $100 for each new Windows 8 or Windows Phone app published in their respective stores.\nIf you're a developer, and Microsoft isn't paying you to develop Windows 8 apps, then you face two awkward facts: Windows 8 tablets have just 2 percent of the tablet market, according to Gartner, and Windows 8\/8.1 represents less than 11 percent of total Windows installations, compared to 47 percent for Windows 7 and nearly 30 percent for Windows XP, according to NetApplications.\nGiven that, why should you bother developing for Windows 8 at all? \nO'Brien has two answers. "Some app stores have thousands and thousands of apps, so some developers struggle to differentiate themselves," he says. With fewer apps in the Windows Store, you face less competition, in other words.\n[ Case Study: How Responsive Website Design Helps Boost Revenue ]\n[ Commentary: Why Responsive Web Design Is Here to Stay ]\nIn addition, if you choose to make Windows 8 applications, you can make versions that look similar on PCs and mobile devices. "We believe that the next generation of app experiences will be PC, tablet and phone experiences," O'Brien says. "We compete with Apple and Google, but they treat the tablet and phone as completely different from a desktop or laptop device." \nThis might be more significant were it a simple matter of developing once and publishing to desktop, tablet and phone \u2014 but O'Brien admits that that isn't the case yet. "You can reuse the skills and code. It's not easy today, but it will be," he says. It's also not clear that many developers are sold on the benefits of producing similar applications for PCs, mobile devices and phones. \nWindows 8 Development Incentives More Than Cold, Hard Cash\nPaying software vendors to produce Windows Store apps isn't the only way Microsoft encourages Windows 8 development today. Other incentives include the following:\nApp Builder Rewards encourages Windows 8 and Windows Phone app development among U.S.-based developers. You earn points by attending events and building and publishing apps; points can be exchanged for Xbox games, a Windows Store developer account or a copy of Windows 8.\nThe Unity incentive program promotes the use of the Unity development platform for building Windows 8 and Windows Phone games and apps. It includes a free Dev Center account, a free Windows 8 Pro license and a free phone or tablet.\nMicrosoft's free development resources include tips on turning iPad apps into Windows Store apps.\nCommon registration for Windows 8 and Windows Phone is intended to make it as convenient as possible to build applications for the Windows Store and the Windows Phone store.\nFinally, Microsoft is seeding the market with discounted Windows 8 PCs through a $100 discount to Windows XP users who buy a new Windows 8 PC.\nThere are also more general Microsoft incentives, O'Brien adds. "If you register as a developer, you get thousands of dollars' worth of software for development, and access to programs [such as] MSDN," the Microsoft Developer Network.\nWhere Will Future Windows 8 Developers Come From?\nIt's impossible to know whether these incentives will be enough to get developers to build Windows 8 apps in any significant way, but Miller says he feels that, in the long term, there's another conundrum that Microsoft will have to solve if Windows 8 is to become a big success: Where are new Windows 8 developers going to come from? \n"Universities and courseware teaches for iOS or Android or Java," he points out. "It's definitely a problem for Microsoft because the (Windows 8) technology is new and evolving. It's hard for someone to train on a platform when it's not still or stable."\nPaul Rubens is a technology journalist based in England. Contact him at firstname.lastname@example.org. 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