the next sonic game is sonic 4! that's a 2D game! i can't wait!
If you mean in 2012, there is Sonic and All-Stars Racing: Transformed coming out sometime later on in the year.There's also the rumor of Sonic Dimensions, but no one has officially proved it'll become a game just yet.
Sonic Generations
Sonic the hedgehog is a video game to Xbox360 and Playstation3. the game is also called Sonic Next-Gen or Sonic 06 to not be mixed up with the first Sonic game.
the next sonic is sonic the burning underground
sonic colors.
The next Mario game will come out Late december of 2013 and will be Mario and Sonic: Winter Olympics 2013
sonic Rider Zero Gravity noob
Sonic and the Black Knight
It is not known as of yet if there will be another game in the Sonic Riders series.
sonic the end
Mario & Sonic At The Olympic Winter Games is coming out late 2009 for the Wii and DS.Sonic & SEGA All-Stars Racing is coming out around early 2010 for Wii, DS, Xbox 360, and PlayStation 3.
the full game is coming on october 2007 sonic test run full version is never coming