The release notes for 5.3.0b1 say that support for the Windows Store 8.0 SDK build target was removed. I didn't notice that when I had 5.3.0b1 installed but I just updated to 5.3.0b2 and (unless I made a mistake during the install) it looks like the Windows Store 8.1 SDK build target has been removed as well. Only the Window Store Universal 10 SDK build target remains. Was this an oversight or on purpose (or my mistake)? I know that the WinRT device market is probably too small to care about (and the mobile GPUs they use will lose support next year) but there have to be many millions of PCs running Windows 8.1 (running supported GPUs) that won't update to Windows 10 anytime soon. Unless it's too much work for Unity to manage, having the Windows Store 8.1 SDK as a build target would be a welcome option.