The following are known Game Genie Codes for Sonic the Hedgehog 2 on SEGA Genesis.

There are two versions of the game, if the codes for “Version A” below do not work, use the “Version B” codes further down the list.
• Master Code – Must Be On
  ATBT-AA4E
  Note: It is known this is required on emulators but may not be required on an actual Genesis console.
• Invisible Sonic
  R0TA-DERP
• Enable Debugger
  AE7T-AAE2
• Sonic’s Ring Count Goes To 99 You Get Hit 4
  NNTT-CACY
• Tails’ Ring Count Goes To 99 When You Get Hit 5
  NNTT-CADJ
• Don’t Use Up Rings To Maintain Transformation of Super Sonic
  ACZT-CAFY
• Become Super Sonic With 0 Rings
  ACZT-CACJ
• Become Super Sonic With 0 Emeralds
  ACZT-CACA
• The Regular Level Music Plays When Super Sonic, Instead of The Super Theme
  ADFT-8AF6

Version A Codes

• Rings Worth 2 (Player 1
  SAST-DJ1A
• Rings Worth 3 (Player 1)
  SAST-DN1A
• Rings Worth 4 (Player 1)
  SAST-DT1A
• Rings Worth 5 (Player 1)
  SAST-DY1A
• Rings Worth 6 (Player 1)
  SAST-D21A
• Rings Worth 7 (Player 1)
  SAST-D61A
• Rings Worth 8 (Player 1)
  SAST-DA1A
• Start With 1 Life Instead Of 3 (Player 1)
  AE8A-AAD2
• Start With 5 Lives (Player 1)
  AY8A-AAD2
• Start With 7 Lives (Player 1)
  A68A-AAD2
• Start With 9 Lives (Player 1)
  BE8A-AAD2
• Start With 25 Lives (Player 1)
  DE8A-AAD2
• Start With 50 Lives (Player 1)
  GJ8A-AAD2
• Start With 75 Lives (Player 1)
  KN8A-AAD2
• Start With 99 Lives (Player 1)
  NN8A-AAD2
• Infinite Lives (Player 1)
  JW3A-CA4J
• Rings Worth 2 (Player 2)
  SATA-DJVW
• Rings Worth 3 (Player 2)
  SATA-DNVW
• Rings Worth 4 (Player 2)
  SATA-DTVW
• Rings Worth 5 (Player 2)
  SATA-DYVW
• Rings Worth 6 (Player 2)
  SATA-D2VW
• Rings Worth 7 (Player 2)
  SATA-D6VW
• Rings Worth 8 (Player 2)
  SATA-DAVW
• Start With 1 Life Instead Of 3 (Player 2)
  AE8A-AAD8
• Start With 5 Lives (Player 2)
  AY8A-AAD8
• Start With 7 Lives (Player 2)
  A68A-AAD8
• Start With 9 Lives (Player 2)
  BE8A-AAD8
• Start With 25 Lives (Player 2)
  DE8A-AAD8
• Start With 50 Lives (Player 2)
  GJ8A-AAD8
• Start With 75 Lives (Player 2)
  KN8A-AAD8
• Start With 99 Lives (Player 2)
  NN8A-AAD8
• Infinite Lives (Player 2)
  JXGA-CA7G
• Jump Lower
  KBVT-CAE2
• Jump A Little Higher
  FVVT-CAE2
• Jump A Lot Higher
  EBVT-CAE2
• Jump Really High
  CBVT-CAE2
• Sonic Stays Invincible For A Shorter Time After Getting Hit
  A02T-CAF8
• Sonic Stays Invincible For A Longer Time After Getting Hit
  982T-CAF8
• Sonic Becomes Invisible And Invincible For The Rest Of The Level After Getting Hit (Must Have At Least One Ring – Switch Off And Then On To Make Sonic Visible)
  ALTA-CA8N
• Once Invincible (Stars), Sonic Stays Invincible For The Rest Of The Level
  ALTA-CA9J
• Sonic Doesn’t Lose Rings When Hit
  ATTT-CA4W
• Tails Doesn’t Lose Rings When Hit
  ATTT-CA5G
• Sonic Needs Only 1 Ring Instead Of 50 To Enter Special Stage After Touching A Star Post
  AH2T-CAH6
• Rings Worth 2 In Special Stages (Sonic)
  SBJA-HJWJ
• Rings Worth 3 In Special Stages (Sonic)
  SBJA-HNWJ
• Rings Worth 4 In Special Stages (Sonic)
  SBJA-HTWJ
• Rings Worth 5 In Special Stages (Sonic)
  SBJA-HYWJ
• Rings Worth 6 In Special Stages (Sonic)
  SBJA-H2WJ
• Rings Worth 7 In Special Stages (Sonic)
  SBJA-H6WJ
• Rings Worth 8 In Special Stages (Sonic)
  SBJA-HAWJ
• Rings Worth 2 In Special Stages (Tails)
  SBJA-HJWR
• Rings Worth 3 In Special Stages (Tails)
  SBJA-HNWR
• Rings Worth 4 In Special Stages (Tails)
  SBJA-HTWR
• Rings Worth 5 In Special Stages (Tails)
  SBJA-HYWR
• Rings Worth 6 In Special Stages (Tails)
  SBJA-H2WR
• Rings Worth 7 In Special Stages (Tails)
  SBJA-H6WR
• Rings Worth 8 In Special Stages (Tails)
  SBJA-HAWR
• Need 0 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ACZT-CACA
• Need 1 Chaos Emerald To Become Super Sonic (In Addition To Rings)
  AGZT-CACA
• Need 2 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ALZT-CACA
• Need 3 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ARZT-CACA
• Need 4 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  AWZT-CACA
• Need 5 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  A0ZT-CACA
• Need 6 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  A4ZT-CACA
• Need 1 Ring To Become Super Sonic (In Addition To Chaos Emeralds – Don’t Lose Rings With Time
  AGZT-CACJ
  K4ZT-CA9N
• Need 5 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  A0ZT-CACJ
• Need 10 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  BLZT-CACJ
• Need 25 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  DGZT-CACJ
• Need 40 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  FCZT-CACJ
• Super Sonic Doesn’t Lose Rings With Time
  K4ZT-CA9N
• Level Select Menu (At Title Screen, Hold Down A While Pressing Start)
  RE8A-A60W
• Start Most Levels With Some Rings (1-Player Game Only – The Number Of Rings Varies With The Stage, And You Can Still Lose Rings)
  2VAT-BCRN

Version B Codes

• Rings Worth 2 (Player 1)
  SATA-DJTJ
• Rings Worth 3 (Player 1)
  SATA-DNTJ
• Rings Worth 4 (Player 1)
  SATA-DTTJ
• Rings Worth 5 (Player 1)
  SATA-DYTJ
• Rings Worth 6 (Player 1)
  SATA-D2TJ
• Rings Worth 7 (Player 1)
  SATA-D6TJ
• Rings Worth 8 (Player 1)
  SATA-DATJ
• Start With 1 Life Instead Of 3 (Player 1)
  AE8A-AADN
• Start With 5 Lives (Player 1)
  AY8A-AADN
• Start With 7 Lives (Player 1)
  A68A-AADN
• Start With 9 Lives (Player 1)
  BE8A-AADN
• Start With 25 Lives (Player 1)
  DE8A-AADN
• Start With 50 Lives (Player 1)
  GJ8A-AADN
• Start With 75 Lives (Player 1)
  KN8A-AADN
• Start With 99 Lives (Player 1)
  NN8A-AADN
• Infinite Lives (Player 1)
  JW3A-CA4Y
• Rings Worth 2 (Player 2)
  SATA-DJW8
• Rings Worth 3 (Player 2)
  SATA-DNW8
• Rings Worth 4 (Player 2)
  SATA-DTW8
• Rings Worth 5 (Player 2)
  SATA-DYW8
• Rings Worth 6 (Player 2)
  SATA-D2W8
• Rings Worth 7 (Player 2)
  SATA-D6W8
• Rings Worth 8 (Player 2)
  SATA-DAW8
• Start With 1 Life Instead Of 3 (Player 2)
  AE8A-AADW
• Start With 5 Lives (Player 2)
  AY8A-AADW
• Start With 7 Lives (Player 2)
  A68A-AADW
• Start With 9 Lives (Player 2)
  BE8A-AADW
• Start With 25 Lives (Player 2)
  DE8A-AADW
• Start With 50 Lives (Player 2)
  GJ8A-AADW
• Start With 75 Lives (Player 2)
  KN8A-AADW
• Start With 99 Lives (Player 2)
  NN8A-AADW
• Infinite Lives (Player 2)
  JXGA-CA7W
• Jump Lower
  KBVT-CAE2
• Jump A Little Higher
  FVVT-CAE2
• Jump A Lot Higher
  EBVT-CAE2
• Jump Really High
  CBVT-CAE2
• Sonic Stays Invincible For A Shorter Time After Getting Hit
  A02T-CAGL
• Sonic Stays Invincible For A Longer Time After Getting Hit
  982T-CAGL
• Sonic Becomes Invisible And Invincible For The Rest Of The Level After Getting Hit (Must Have At Least One Ring – Switch Off And Then On To Make Sonic Visible)
  ALTA-CA82
• Once Invincible (Stars), Sonic Stays Invincible For The Rest Of The Level
  ALTA-CA9Y
• Sonic Doesn’t Lose Rings When Hit
  ATTT-CA58
• Tails Doesn’t Lose Rings When Hit
  ATTT-CA6W
• Sonic Needs Only 1 Ring Instead Of 50 To Enter Special Stage After Touching A Star Post
  AH2T-CAHN
• Rings Worth 2 In Special Stages (Sonic)
  SBJA-HJV2
• Rings Worth 3 In Special Stages (Sonic)
  SBJA-HNV2
• Rings Worth 4 In Special Stages (Sonic)
  SBJA-HTV2
• Rings Worth 5 In Special Stages (Sonic)
  SBJA-HYV2
• Rings Worth 6 In Special Stages (Sonic)
  SBJA-H2V2
• Rings Worth 7 In Special Stages (Sonic)
  SBJA-H6V2
• Rings Worth 8 In Special Stages (Sonic)
  SBJA-HAV2
• Rings Worth 2 In Special Stages (Tails)
  SBJA-HJV8
• Rings Worth 3 In Special Stages (Tails)
  SBJA-HNV8
• Rings Worth 4 In Special Stages (Tails)
  SBJA-HTV8
• Rings Worth 5 In Special Stages (Tails)
  SBJA-HYV8
• Rings Worth 6 In Special Stages (Tails)
  SBJA-H2V8
• Rings Worth 7 In Special Stages (Tails)
  SBJA-H6V8
• Rings Worth 8 In Special Stages (Tails)
  SBJA-HAV8
• Need 0 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ACZT-CACN
• Need 1 Chaos Emerald To Become Super Sonic (In Addition To Rings)
  AGZT-CACN
• Need 2 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ALZT-CACN
• Need 3 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  ARZT-CACN
• Need 4 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  AWZT-CACN
• Need 5 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  A0ZT-CACN
• Need 6 Chaos Emeralds To Become Super Sonic (In Addition To Rings)
  A4ZT-CACN
• Need 1 Ring To Become Super Sonic (In Addition To Chaos Emeralds – Don’t Lose Rings With Time
  AGZT-CACY
  K4ZT-CA92
• Need 5 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  A0ZT-CACY
• Need 10 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  BLZT-CACY
• Need 25 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  DGZT-CACY
• Need 40 Rings To Become Super Sonic (In Addition To Chaos Emeralds)
  FCZT-CACY
• Super Sonic Doesn’t Lose Rings With Time
  K4ZT-CA92
• Level Select Menu (At Title Screen, Hold Down A While Pressing Start)
  RE8A-A60G
• Start Most Levels With Some Rings (1-Player Game Only – The Number Of Rings Varies With The Stage, And You Can Still Lose Rings)
  2VAT-BCRA
• One Hit And You Are Invincible
  982T-C9F8