OS/2 always intrigued me because it looked like a strange cousin of Windows; it so clearly shared the design language (and some actual code) with that family of operating systems.

Well, the Windows NT family (which includes Windows 2000, Windows XP, Windows 7, Windows 10) is a descendant of OS/2. In fact, Windows NT 3.1 was basically a reskinned OS/2.

I remember fond days of playing several MSDOS games at once under OS/2 (Elite: Frontier and Colonization, iirc) while Windows 95 failed to play any of them :)

This isn't quite true. Microsoft and IBM were working on OS/2 together and Microsoft got fed up with the development delays and decided to build their own system. So NT was designed from the ground up. It originally had multiple subsystems (Win16, Win32, Posix) one of which included an OS/2 1.0 subsystem.

https://www.itprotoday.com/compute-engines/windows-nt-and-vm...

With WSL bringing back the spirit of a POSIX-flavored subsystem, it might be fun to see some other retro-computing subsystems such as a modern OS/2 subsystem, though I can't think of a good reason to do that other than fun.

Maybe if someone can think of a good reason to need OS/2 running on Azure it could happen. Maybe there's a bank somewhere with the OS/2 apps investment and enough money to throw at Microsoft (and IBM) somewhere to make it happen.

Also Microsoft already gave up on WSL1's subsystem approach and just made the VM-based WSL2, focused on fixing the UX issues with VMs.

WSL2 is certainly doing fewer kernel interactions as a subsystem than WSL1, but my impression is that it is still classified as a subsystem in the way that it launches and manages its more VM-like approach.

The comparison/analogy I've heard, and I'm not sure it is apocryphal but it certainly makes sense to me, is to the Xbox One's game subsystems, which while rarely described in great detail from an NT Kernel engineering standpoint, when they are briefly described as such they are often described as subsystems and that they are "VM-like" in operation.

https://en.m.wikipedia.org/wiki/Windows_Subsystem_for_Linux

https://github.com/microsoft/WSL2-Linux-Kernel

The Xbox One also uses a hypervisor to run multiple OSes, one of which was Windows 8:

https://en.m.wikipedia.org/wiki/Xbox_One_system_software

https://wccftech.com/xbox-one-architecture-explained-runs-wi...

They started doing that with the Xbox 360.