Board Thread:Speculation, Theories, and Rumors/@comment-25400375-20160826210326/@comment-25400375-20170327173729

Mystic Monkey wrote: The Deadly Six reminds me more of the Koopalings from the Super Mario series.

Observer Supreme wrote: the whole two Earths thing I've been hearing about turns out to be correct. Takashi Iizuka once said in an interview that the games takes place between two worlds, one is human, and one is set on the non-human side. Sonic Colours is set on the non-human side. Sonic can freely travel between the two.

However most fans believe he was being figurative, that by world he means social communities between humans and Sonic's kind. Personally, I like to think he was speaking figuratively as well.