Building the software translation (i.e. emulation) layer and testing / validating the top 20 or so most popular "apps": social media, spotify, office, etc. I think most of these are ARM native.

> What are game developers told to do to make their games compatible?

Qualcomm gave a GDC talk about this, though I can't seem to find it now. There are a handful of options, including just running it via x86 emulation. You can also recompile for ARM directly, or use some kind of hybrid solution where some system-related components use native ARM code and the rest remains emulated x86.

I'm no more a fan of Microsoft than the next average HN reader, but I think Microsoft is doing some real leg work here. That being said, I get the impression that it's very much Qualcomm-driven.

Disclaimer: Qualcomm employee but don't have anything to do with any of this