New Sonic the Hedgehog (1991) prototype uncovered by preservation groups - Tails' Channel

A prototype of Sonic the Hedgehog (1991) was showcased by a video game preservation group in a New Year's Eve livestream.

Play Genesis Sonic the Hedgehog (Prototype) Online in your browser

Sonic the Continuation Reviews Newbie's Perspective: – CrystalMaiden77

Sonic the Hedgehog 2 (August 21st, 1992 Prototype) : Free Borrow & Streaming : Internet Archive

The Long History of Sonic Prototypes/Unused Content

New Sonic game prototypes found by drx, shows early stages from Sonic CD, more to come

Sonic the Hedgehog 3/Development/Music - Sonic Retro

7 Sonic The Hedgehog Prototypes You Were Never Meant To Play

Sonic the Hedgehog (Prototype) LOST BITS Altered & Unused Content [TetraBitGaming]

21 Crazy Facts About Sonic and the Console War He Started - IGN

Sonic the Hedgehog (1991) prototype discovered - The Independent Video Game Community

7 Sonic The Hedgehog Prototypes You Were Never Meant To Play

Brand new Sonic Heroes prototypes uncovered - Tails' Channel