Sonic Unleashed producer says making an HD 2D Sonic might not be viable.
New title to be unveiled at the German video games event next week.
The low quality of the first Sonic game for this generation is put down to 'coming to grips with the technology'.
Sonic Unleashed is not coming to DS and Beijing 2008 is not being released for Wii.
Empire: Total War, Alpha Protocol and Madworld join it for a brilliant looking Q1 2009.
New game will have more in common with the Adventure series than more recent Sonic titles.