*The Nintendo 3DS version is being co-developed by Sonic Team and Dimps.
* The director of the 3DS version is Tetsu Katano, who directed Sonic and the Black Knight.
* 2D side-scrolling gameplay for both Classic Sonic and Modern Sonic.
* Momentum based gameplay and platforming are fully featured in the Classic Sonic gameplay.
* Modern Sonic plays a lot like the Sonic Rush games and Nintendo DS version of Sonic Colours.
* Nintendo 3DS version will have exclusive stages and boss stages.
* Green Hill Zone will be the only shared stage in both the HD console version and Nintendo 3DS version.
* Casino Night Zone from Sonic the Hedgehog 2 is confirmed for the Nintendo 3DS version.
* Story has some differences between the console and Nintendo 3DS versions, but will be fundamentally the same.
* Console version will have many characters, but the Nintendo 3DS version will only feature the ones who are integral to the story.
* There is no Wii version. Sonic Team head Takashi Iizuka says this is because “The primary goal for the console versions of Generations was reimagining the series’s classic zones in vivid, high-definition graphics.”
* Sonic the Hedgehog 3‘s Launch Base Zone ‘Big Arm’ boss fight is in the game, which suggests that stage is also in the game.
* Classic Eggman appears in the above mentioned boss.
* Exclusive to the Nintendo 3DS version are challenges that you can unlock via StreetPass or Play Coins.
* The game also features an exclusive two-player race mode via local wireless connection.
* Modern Sonic stages take advantage of the 3D feature more than the Classic Sonic stages. An example shown and detailed is a part in the Green Hill Zone where Modern Sonic smashes through the bottom of a giant totem pole. The camera then moves to the front of Sonic and lets you see the rest of the pole collapse behind Sonic as he escapes.
* The 3D depth is also highlighted when Modern Sonic occasionally moves between the foreground and the background.
* Jun Senoue and his music team are working on the music for the game.
* Nintendo Power thinks the handful of tracks they’ve heard so far are “fantastic”.
* Special Stages are confirmed and are designed in Sonic Heroes style. As expected, you earn Chaos Emeralds from these stages. Whether or not Super Sonic will be your reward for earning all Chaos Emeralds is unclear right now.