Zone: 0 > Sonic 1 > Background Information

Complete - Orbinaut Framework: Green Hill Pack

Proto:Sonic the Hedgehog (Genesis)/Green Hill Zone - The Cutting Room Floor

Sonic The Hedgeblog on X: Early screenshots of Labyrinth Zone in 'Sonic 1′ had a very different background. With the prototype, we can now see that design in its entirely! Via the @

Sonic for the Master System - An Oddball Retrospective! - Indie Hive

Green Hill Zone (Sonic the Hedgehog), Sonic Wiki Zone

Sonic Origins for Nintendo Switch - Nintendo Official Site

Zone: 0 > Sonic 1 > Downloads

Sonic Superstars review: fun 2D throwback takes things slow

Random: Wait A Sec, That Sure Looks Like Mario In Sonic The Hedgehog's Marble Zone

Sonic 1 Prototype Played on Real Hardware with Final Copy Side-by-Side Comparison : r/SEGAGENESIS

Sonic Origins Plus cheat codes: find Hidden Palace Zone and get Super Sonic - Video Games on Sports Illustrated