Microsoft releases experimental Windows 10 Build 21277 with new emoji and x64 emulation on ARM PCs
From now, Windows 10 Insiders on the Dev Channel currently have the choice of installing preview builds from the FE_RELEASE or RS_PRERELEASE branches. By default, Insiders will get flights like new Build 20277 from the FE_RELEASE branch, but you can switch to RS_PRERELEASE if you’re feeling more adventurous.
To get the alternative download, Build 21277, you will have to actively choose to download it via Windows Update. Be warned though, once you’ve switched to RS_PRERELEASE you won’t be able to download FE_RELEASE builds any more.