From http://wiiudaily.com...ng-development/
Sonic Boom: Rise of Lyric released last year on the Wii U to some what tepid reception. Many fans of the original Sonic series felt the reboot was done to make Sonic more in line with traditional game characters, instead of his trademark “gotta go fast” gameplay. It led many to not bother picking up the game, since it is a vast departure from Sonic games of the past and is meant to tie-in with the cartoon reboot Sega had planned.
While Sonic Boom may not have been well received, Sonic Stadium has uncovered several pieces of evidence that suggest Sega had the team at Big Red Button working on a game that was much more like traditional Sonic games, before it was scrapped. The name of that game was Sonic Synergy. According to the findings, the new character models that were so contentious among Sonic fans were actually reworked about halfway through development.