I think Tails is able to play in 1-P mode after you win the game with Sonic, defeating the neutral enemies the hard way. Never did, just making a guess. And probably the least possible thing is you can play Amy if you win with Tails if you don't make flights with with the Tail-copter ability (how am I supposed to know?! I never had an extra SEGA controller!!!). And maybe you can unlock Knuckles for 1-P mode (I hope they make the Super SEGA so I can know about 3-P and 4-P mode characters) if you defeat the neutral enemies in a different kind of way. Just guessing. I'm not a SEGA admin. Oh. And by the way, still not completely satisfied. Though you have jacked it up 40%.