Gameboy color dinosaur JRPG / metroidvania that seemingly no one else has ever played. Called Dinosaur’us. I had to google the name there and it turns out there is a wikipedia page so it’s not totally obscure - https://en.m.wikipedia.org/wiki/Dinosaur’us

I loved this game as a kid! There are surprisingly few good dinosaur games (although admittedly a lot of good dragon ones).

Edit: only ever released in the UK - that explains a lot of why it was so obscure. The ROM is on emulator sites though if you are curious.