While the gameplay shown so far doesn't look exactly like any one Sonic game, it conjures up memories of two of the strongest titles from the 'hog's recent past: Sonic Adventure for its diverse ground-burrowing, monkey swinging, tail-propelling, multi-character gameplay and Sonic Heroes for the fact that several characters are on-screen at the same time and must be used together to progress. Quite how you'll switch between them remains to be seen, but the three-character mechanic of Sonic Heroes was one of that game's greatest strengths, resulting in impressive and devastating displays of spiny attacks at a moment's notice. It's probably no coincidence that both those games appeared on GameCube; this is a Nintendo fan's Sonic title and no mistake.
Interestingly, it's not the standard version of CryEngine 3 used here, but one that has been enhanced by the team. According to Rafei, the technology's usual spec can't traditionally do split-screen gaming, yet Sonic Boom will feature a twin split-screen display, one on the TV screen and the other on the GamePad. "We worked in close contact with [CryEngine creator] Crytek in Germany," explains Rafei, "and the team there is pretty excited about that as well. In the end, it was simply the right choice for the project."
