Apologies in advance if this is nothing new - I admit I'm not keeping up with these things right now. In that recent, super long interview with Naoto Ohshima in the new Beep21 online magazine in Japan (it costs 500 yen to access but is worth it), he made some brief comments that might be of interest. First, there's a photo of an early design doc for Sonic (before it was Sonic; ignore the page on the left with the drawing of Shoichiro Irimajiri - that was for a Dreamcast promotional event): And the caption for the photo, written by Ohshima: "I recently found the second draft of the proposal for Sonic. This was created by myself and Hayashida (Kotaro, who was then chief of the planning section). For the first draft, the main characters were called Twin Star, a pair of boys who fought against nightmares. In the second draft, there are remnants of the word 'nightmare.' After that, I joined with Yuji Naka, and the character became the hedgehog called Sonic." I can't translate all of the page from the photo now, but it outlines the type of game (horizontal left-to-right scrolling), how enemies are defeated (see below), and the bosses. The main boss is called Thirteen (or Nightmare Thirteen) and can be seen at the bottom of the page. Enemies are defeated by rolling into them: The doc says "enemies are defeated using a 'rolling attack' (Wonder Hedgehog)." So the rolling attack apparently existed even before Naka was involved and before the character was a hedgehog (presumably?), and the attack seems to have been called 'Wonder Hedgehog'. The interview has a ton of other interesting info about Ohshima, including the story of how he met with Nintendo's Shigeru Miyamoto (the creator of Mario) before Ohshima began working on Sonic, and that experience motivated him to attempt to make something greater than Mario. Ohshima also comments on the 1990 Tokyo Toy Show: "We showed a teaser of Sonic at the June 1990 Tokyo Toy Show. However, it didn't even have a single enemy finished. It was just footage showing off the multi-layered scrolling and the feeling of speed." (He uses the word 映像 'eizou' to refer to the teaser, which indicates it's a video recording or something like that rather than a playable demo). And a photo of the 1990 Tokyo Toy Show: Edit: Check this post for more info. Edit 2: Even more info in this post.