Earlier today a new, unreleased Windows 10 build was leaked onto file-sharing sites, build 9888 has several new features including new animations and offline maps.
After the official release of build 9879, Microsoft announced that it would release any new builds to the Insider program before 2015. Thanks to this leak, first available on MyDigitalLife, we have yet another build to play with while we’re waiting for an official release. This build is the first known build to have the 10.0 kernel first reported last week. It also features new animations for maximizing and restoring windows along with an improved Settings app; The settings app now comes with an updated version of Battery Saver and a new Offline Maps options, yet another Windows Phone feature showing up in Windows 10. Check out the video below for a full run-down of all the new stuff.
We do not recommend you try this build yourself, as it was never intended for the public and it might very well block any further Windows Insider builds from downloading.