Hi all.

Rule 4.  Must work in Windows 10. Web builds are fine.

But outside the rules section it says that games developed for a real game boy are acceptable.

Can I just confirm that 'proper' GameBoy titles are valid (if they run in a windows 10 based emulator) in the jam before I start.   

Yup! ROMs are acceptable, and they'll be judged in BGB, so you should probably use that for testing. I've added that detail to the jam page.