Despite this year being a very good one for Sonic preservation with things like prototypes and lost Dreamcast DLC being found, there's still one last piece of Sonic lost media that personally perplexes me - the early intro for the 1993 show Sonic the Hedgehog, referred to as Sonic SatAM by fans.
While we do have a full version of the intro, it's only the storyboard version that was released in the complete DVD box-set for the show. It can be found here: youtu.be/4W-wKw6sPlA
However, a fully-animated version did exist at some point, as cels from it have surfaced over the years. They can be found on the page for the intro on the LMW. We also have around 10 seconds or so of screen time for the intro, as uploaded by the YouTube channel Tails Channel: youtu.be/ASm3aMvnF_M (The short clip seems to have been taken at some kind of Sega convention, as a clip of SegaSonic the Hedgehog, a Sonic arcade game released in 1993, is shown as well.)
The only way we could get this released in some way, (if it even still exists) is to somehow contact people who worked on the series and the storyboard.