Learn more about the themes and ideas that went into Sonic CD.

We fondly remember playing Sonic CD on the ill-fated Mega CD add-on. We never dreamed at the time that all of the game's ideas existed inside a couple of low-key sketch-books. But that's exactly what Sonic Team's art director, Kazuyuki Hoshino, has shown off in a developer diary preempting the digital re-release of Sonic CD on the PlayStation Network today.

Watch the fascinating video after the jump.