Was the Sonic Spinball port much different than the Game Gear version? My understanding is the Game Gear port was by Sega and the two systems are very similar.
You're right: many of TecToy's Brazil-exclusive Master System games were tweaked versions of Game Gear releases. That includes games like Ecco 2, Mortal Kombat 3 and Sonic Blast, but not the aforementioned Street Fighter II which they developed independently.
I think the Master System version of Sonic Spinball came from Sega themselves though. It was sold in Europe as well as Brazil.
