Classic Sonic were a true mavel that showed us platforming mixed with something not heavily experimented at the time. Speed. No other game could let you platform like Mario, and zip through a level like a race car. Eventually however, they tried experimenting with 3D, and thus started the spiral downward. Failure after failure, SEGA promised for Sonic's 20th birthday, they would return to what made Sonic famous. Classic 2D platforming and a perfected 3D modern Sonic mode. For a Sonic fan, it was a dream come true. The game plays like a trip down memory lane, mixing levels from Sonic games over the past 20 years. The 2D mode plays just like it should, like Sonic the Hedgehog 2. The speed you can build up is spectacular and reminds you why you love Sonic. The 3D mode enables you to boost and speed through levels as fast as you wish. THIS is how all 3D Sonic games should have been. This game also has music and remixes from the whole series, which you can select to use whenever you want. With collectables and challenges, you'll be playing this for a while. Sonic has done it once more. This game is a tribute to the entire series that Sonic fans, new and old, can enjoy.