[sirjaz]

It's a Windows container. It runs the NT kernel and a few minimal other things. The closest would be the Nano Server container

[qalmakka]

AFAIK it's more like a reimplementation of NT APIs in userspace - aka basically Wine with extra steps, or Linux UM. There was a slide deck going around about Project Drawbridge, here: https://threedots.ovh/slides/Drawbridge.pdf