I have successfully tested SNIS on a Windows machine. That being said there is not (yet) a Windows port. I was able to run it using Xming and PuTTY (SSH) to play the snis_limited_client remotely from a Linux machine. The normal snis_client had significantly lag on helm and other screens. I'm sure this had to do with trying to run OpenGL over SSH on an unaccelerated X session.
It's still best to run Space Nerds In Space natively on Linux, but, if for some reason you can't, there is a way to play on Windows via another Linux computer.