Sonic the Hedgehog 2 (Aug 21, 1992 prototype) - Hidden Palace

A prototype of Sonic the Hedgehog 2 for the Sega Mega Drive.

Sonic the Hedgehog 2 - Wikipedia

Sega Genesis / 32X - Sonic the Hedgehog 2 (Prototypes) - The Spriters Resource

Sonic the Hedgehog 2 (Aug 21, 1992 prototype) - Hidden Palace

Proto:Sonic the Hedgehog 2 (Genesis)/August 21st, 1992 - The Cutting Room Floor

Proto:Sonic the Hedgehog 2 (Genesis)/August 21st, 1992 - The Cutting Room Floor

Genesis / 32X / SCD - Sonic the Hedgehog 2 (Prototypes) - Casino Night Zone (Aug. 21, 1992) - The Spriters Resource

Sonic the Hedgehog 2, Sonic Wiki Zone

Sonic the Hedgehog 2 (Nick Arcade prototype)

Proto:Sonic the Hedgehog 2 (Genesis)/August 21st, 1992 - The Cutting Room Floor

Steam 工作坊::Sonic the Hedgehog 2 Aug 21, 1992 Prototype

Sega Genesis / 32X - Sonic the Hedgehog 2 (Prototypes) - The Spriters Resource

Sonic the Hedgehog 2 (alpha)/Hidden content - Sonic Retro

Tom Payne and the Box of Sonic 2 Development Disks – MegaBites

Sonic the Hedgehog 2 (Aug 21, 1992 prototype) - Walkthrough