http://www.hardcoregaming101.net/segasonic-the-hedgehog/
Well, the main series has been covered, so here is one of the first spin-offs: the super obscure arcade game that was so badly received it wasn't even released officially in North America. It's never been ported either, though part of that has to do with it using a trackball - it's playable without it, but it's messing something. Anyway, Sonic Mania Plus came out today so now you can read about the origins of Mighty and Ray.