This new version of the SEGA classic offers a different game mode: Cooperative game where you'll be able to control three different characters at the same time to reach the goal.
Open Sonic offers interaction between the game and the user. It's a different platform game. In Open Sonic you'll have to think a bit to reach the end of each level. You'll need strategy and three characters for example to open doors or jump even higher.
The game is still in development phase, but the two levels included give you some minutes of fun and make us expect it will be amazing when finished.
Finally, Open Sonic also includes a level editor, so you can create your own levels and play in your own Sonic universe.