Okay! Please try https://zuluinuoe.itch.io/magnetic-drift-test again.
It -should- work now. Needed to monkey-patch cl-soil to work around what seems to be a cffi 'feature'
And with regards to libffi, it's primarily configuring pkg-config correctly, which is a bit of a pain. If I remember correctly, I installed libffi through msys2, and then set up my PK_CONFIG_PATH. It was a bit ago, so I'll need to rediscover all the steps, especially since I'm trying to get an x86 build going.