A lost Sonic arcade game was recently found by a collector who goes by the name ShouTime. After a couple years of teasing with off-screen photos, SegaSonic Bros. has been brought to the California Extreme arcade expo for play. This puzzle game was initially planned for release in 1992, but never quite made it out the door.
The mechanics seem fairly complicated. Blocks of four, comprised of three colors — red, blue, and yellow — fall from the top of the screen. The goal is to surround blocks with a like color, like a lasso, which clears said cluster of blocks. The bigger the color loop, the more blocks cleared, which means bigger points (and more electricity zapped into Eggman).
Sonic stars alongside two original characters other Sonics. It's unknown who Red Sonic and Yellow Sonic really were, or if they even had names. You could infer that they're Sonic's brothers based on the title, but, who knows. It's not like they had many characters to work with in 1992.
The game was designed by Fukio Mitsuji, designer of the iconic Bubble Bobble. It received a location test in Japan, but ultimately failed to catch on and was shelved.
It was previously hypothesized that SegaSonic Bros. was an early version of the isometric arcade platformer SegaSonic the Hedgehog (red and yellow do match the color schemes of Mighty and Ray). But, over the last few years, we've seen that was far from accurate.
Other Sonic arcade rarities have recently been found and dumped. Simple “games” such as Waku Waku Sonic Patrol Car, SegaSonic Cosmo Fighter, and even the SegaSonic Popcorn Shop have been released and are now playable in MAME. Hopefully this one gets the same treatment eventually.