Sprite comparison for Mania's intro animation (SegaSonic, Sonic 1, 2 and CD) : r/SonicTheHedgehog

Sonic the Hedgehog CD, Sonic Wiki Zone

Sonic Hacking Contest :: The SHC2022 Contest :: Sonic CD Restored :: By PimpUigi

Having a sonic mainline game tournament. Quarterfinals Round 11, Sonic 2 or Sonic 3 and Knuckles : r/SonicTheHedgehog

Sonic the Hedgehog (LeapFrog Didj) - The Cutting Room Floor

Sonic CD – Hardcore Gaming 101

Sonic & Knuckles - The Cutting Room Floor

The different sonic spirts from Sonic 1 to Mania : r/SonicTheHedgehog

Proto:Sonic the Hedgehog (Genesis) - The Cutting Room Floor

Sonic The Hedgehog Series (Alternate Timeline), Sonic & Sega FanFiction Wiki

Sonic the Hedgehog / What Could Have Been - TV Tropes

Evolution Of SONIC Intro Screen (1991-2021)

SegaSonic the Hedgehog, Sonic Wiki Zone