"Experimental" is a great adjective for Microsoft's WSL (Windows Subsystem for Linux). Not only is it Microsoft's attempt to lure Linux devs into making themselves comfortable in Windows, it also provides a lab for the hacking whizzes who want to see how far they can push the WSL.
The latest such experiment is an attempt to run a third-party Linux distribution, Arch Linux, on the WSL.
The ALWSL project is currently only available in a very unstable dev preview -- essentially a glorified batch file that removes the existing WSL setup, downloads a copy of Arch Linux, verifies its validity, prepares it, and allows it to be booted at the WSL prompt.
By default, WSL uses Ubuntu as the basis for its kernel and userspace, but the underlying subsystem is in theory distribution-agnostic. It simply translates Linux system calls into their Windows counterparts or provides emulation when there isn't a 1:1 match. Consequently, ALWSL needs to do very little on its own to make Arch Linux work.
The project is extremely raw right now, with no real documentation. "If you don't want to break anything, wait for the first release. Which is [of course] not a batchfile," says the project's README.
Regardless, intriguing possibilities are already surfacing. One convenient side effect of the ALWSL project is that it provides a handy utility for backing up and restoring the state of the WSL subsystem. This kicks open the door for a new wave of tinkering with WSL that requires incrementally less heavy lifting.
Some tinkering is already on the way, even though ALWSL isn't ready for prime time. The maintainer of another maverick operating system project, NodeOS, is already interested in developing a system image that can be used with WSL through ALWSL.