Windows 10's upcoming UI, previously known by its code name "Project NEON", is a new design language which is focused on simplicity and consistency along with cool animations. It also adds Windows 7’s Aero Glass-like effects to the Universal app frame and controls. A few days ago, Microsoft started rolling out a new update for the Windows Store app to Windows Insiders in the Fast Ring which features the Fluent Design.
As you may already know, Windows 10 is getting a new appearance for built-in Universal Windows Platform apps like People, Calculator, etc. They are powered by a new design language "NEON" and have new transition effects and transparency with blur. You have a chance to try out these apps in the stable branch of Windows 10.
Microsoft has started working on updating the appearance of the Windows 10 operating system again including the built-in Windows apps. A new design language, codenamed Project NEON, adds more transparency, blur and animations to the user interface of Universal Windows Platform apps. Currently, the apps for Windows Calculator, Windows Camera, Voice Recorder, Paint 3D, and a number of others have received the makeover.