well sonic did give up and walk back home and tails was never in the rest of the bad ending. Also, in sonic 3 and knuckles, you play as sonic. Yet again, no tails. Only for the opening cutscene which sonic imagined it. It seemes that the levels show grief, depression, anger, and faith. One of the levels, tails has an infinate flying power, whicn could never happen, so it's another part that goes on sonic not forgetting about tails.