They used to work: https://ci.appveyor.com/project/djs55/mirage-platform/build/1.0.38 is the passing test for #165 from May of this year, but it appears that no PR since then has successfully built on Appveyor.

It appears to my untrained eye that the combination of us not setting PACKAGE and there not being a single opam file for this repository are causing the usual build path to fail.