Hello, this is Dex, reporting for Tails' Channel. I'd like to share an interesting - if minor - detail I learned while speaking with Takashi Iizuka during Club Chaos last week.
After receiving Iizuka-san's autograph, I asked him about the context behind a piece of concept art shown in Sonic Origins, labeled as "Character Sketch 6" in the game. Due to speculation surrounding the nature of the art, I asked whether the art was just a doodle, or an idea for a game that had yet to materialize. Iizuka responded by saying that this drawing was made to explore ideas he had in his head, but it was never the concept for any particular game he had in mind.
When I asked about the time frame the drawing was made, he stated that he drew the image after developing Shadow 2005.