Sonic the Hedgehog Spinball Cheats For Sega Master System Genesis GameGear - GameSpot

Sonic the Hedgehog 2's Biggest Easter Egg and Other References - IGN

Sonic Origins: How To Access Level Select

Cheat Codes - Sonic the Hedgehog 2 (Megatech) - Sonic Retro

Multiple Cheat Codes For Sonic Mania Have Been Discovered

Sonic 3 & Knuckles ULTIMATE CHEAT GLITCHES!!!

SC Cheats & Glitches: Sonic 3 & Knuckles - Debug & Level Select

Tails' Channel, celebrating 15 years on X: A number of Sonic 3 & Knuckles soundtest features were added in the latest update. @TheOcelot01 recapped all the codes in the list below. #SonicNews

Sonic the Hedgehog 3 (prototype; 1993-11-03)/Hidden content - Sonic Retro

GameShark Sonic Advance 3 Codes, PDF, Japanese Games

Sonic Mania Cheats: Level Select Code, How to Collect Chaos Emeralds, Super Sonic, Special and Bonus Stages