SEGA today revealed a new zone exclusive to the 3DS version of November's upcoming release, Sonic Generations. In the warm springtime era of the zone, you'll play as classic Sonic whereas in the cool sunset-covered autumn act, you'll control modern Sonic in three-dimensions. I can't say which version I'm more looking forward to. Perhaps I'll get them both!
Once again Sonic Generations is due out November of this year to celebrate the 20th anniversary of the blue blur.