itch.io

added credits, the assets should be under a creative commons attribution license

I think there were no rules against fangames during this Jam.   And these developers never claimed Hatsune Miku was their original character, so it should be okay. They gave the credit and made a non serious fangame about said character, so in my opinion this may be a wrongful disqualification

Miku is actually CC-BY-NC - just her voice needs a license but her design is completely fine to use. https://piapro.net/intl/en_for_creators.html here’s the license details direct from the company