Shoutime over on his Tumblr blog has apparently found something quite peculiar - an apparent unreleased Sonic arcade game called Segasonic Bros.
The guy previously helped find and dump roms, such as the Sonic Popcorn Machine and Wakuwaku Sonic Patrol Car, so it's seemingly legit.
This game was designed by the creator of Bubble Bobble, Fukio Mitsuji, this went to location test and failed. According to HG101 the game might have been a prototype (or variant) of the game Popils too.
No gameplay just yet.