At the 2005 Walk of Game induction ceremony, Sega announced that they will be publishing a new 3D Sonic title, currently known as Shadow the Hedgehog. Shadow the Hedgehog will follow on from Sonic Heroes with a focus on action, and a darker theme.
Little is known about Shadow the Hedgehog just yet. Its story, characters, and stages have not yet been confirmed. The only thing Sega has released, is a promotional trailer.
Shadow the Hedgehog is expected to be released at the end of this year.