Big Red Button, the company who was responsible for developing the Sonic Boom video game, has released a bunch of early concept material for the game, including a screenshot of the original start screen. The screenshot suggests that Sonic Boom was originally called Sonic Synergy. In addition to the game title change, the characters had slight alterations as well. Sonic’s arms were still that tan color that people were complaining about and his spikes were slightly different as well.
Source: Sonic Stadium