During its online Windows Developer Day event today, Microsoft tried to get developers excited about building apps and games for its Universal Windows Platform (UWP). The next big release is the Windows 10 Creators Update, coming in “early 2017,” and the Software Development Kit (SDK) for that update is now feature-complete.

Microsoft’s UWP allows developers to build a single app that changes based on your device and screen size. One app can work on your Windows 10 computer, Windows 10 tablet, Windows 10 Mobile smartphone, Windows 10 VR headset, Xbox One console, Internet of Things device, and eventually HoloLens.

Kevin Gallo, director of the Windows Developer Platform, was on stage to detail what’s coming. While many developers have already seen the various new features (including over 1,000 improvements specifically for UWP) via Windows Insider builds, Gallo also unveiled new developer tools and documentation:

  • All of Microsoft’s technical documentation is now available in one place: docs.microsoft.com. The docs are open for feedback from the community, so developers can comment and contribute.
  • Microsoft’s UWP backlog database is being opened up. Developers can now see what the team is working on, help them prioritize bugs, view progress on tracked bugs, and contribute feature requests.

If this sounds familiar, that’s because Microsoft did something similar with its web platform back in May 2014. Now the company is finally expanding the effort to its app platform — the full database will be published over time, though the company didn’t commit to a specific timeframe.

So why is Microsoft making its Windows Developer Day all about UWP? The company will simply say that it’s the best platform for building apps across different types of devices. But there are likely many other reasons, including two in particular that are worth highlighting.

The first is the rumored upcoming edition of Windows 10 that Microsoft likely has up its sleeve called Windows 10 Cloud. As first reported by ZDNet’s Mary Jo Foley, it can only run UWP apps installed from the Windows Store, so it’s really no surprise that the company wants to get developers writing more apps for its store.

The second one Microsoft is talking about much more openly. Windows 10 VR headsets are coming from partners like Acer, Asus, Dell, HP, and Lenovo for prices starting at $299. Those Windows 10 devices, slated for release later this year, run apps — yep, UWP apps.

It really is no surprise Microsoft is pushing UWP.

Windows 10 is a service, meaning it was built in a very different way than its predecessors so it can be regularly updated with not just fixes but new features too. While Microsoft has released many such updates to date, the Creators Update will be a major one and follows the Windows 10 Anniversary Update, released in August 2016.

Gallo emphasized that the Creators Update will greatly expand the API surface available to Windows 10 developers. Many of the existing APIs for Win32 and .NET are now accessible via UWP thanks to the Windows 10 Creators Update SDK. The goal is simple: Bring the worlds of Win32, .NET, and UWP closer together to let developers reuse code as much as possible.

Put another way, Microsoft wants UWP to one day dominate Windows app and game development. That means apps spanning various types of devices, games on Windows and Xbox, and mixed reality.