The following are known Action Replay Codes for Sonic the Hedgehog 2 on SEGA Genesis / Mega Drive (Genesis).

The codes should work with the region specified but may work for other regions as well.

Device Compatibility: Action Replay

• Enable Stage Select 1
  FFFFD0:0100
• Enable Debug Mode
  FFFFFA:0100
• Enable Debug Mode (On An Actual System)
  003B98:0001
• Infinite Rings 2
  FFFE20:00C8
• Infinite Lives
  FFFE12:0009
• Stage/Act Modifier 3
  FFFE10:XXYY
• Always Have 224 Rings (Official Code)
  FFFE21:00E0
• Unlimited Time
  FFFE24:0007
• Super Speed! [Sonic]
  FFF761:6410
• Super Speed! [Tails]
  FFFEC1:6410
• Invincibility For Sonic (Enemies Can’t Touch You) 4
  FFB030:FF
• Invincibility For Tails (Enemies Can’t Touch You)
  FFB070:FF
• Invincibility For Sonic (Always Have Shield) 5
  FFB02B:01
• Invincibility For Tails (Always Have Shield)
  FFB06B:01
• Infinite Time Underwater For Sonic
  FFB028:FA
• Infinite Time Underwater For Tails
  FFB068:FA
• Defeat Stage 1 Robotnik With 1 Hit
  FFB521:01
• Defeat Stage 2 Robotnik With 1 Hit
  FFB621:01
• Defeat Stage 3 Robotnik With 1 Hit
  FFB721:01
• Defeat Stage 4 Robotnik With 1 Hit
  FFB821:01
• Defeat Stage 5 Robotnik With 1 Hit
  FFB921:01
• Defeat Stage 6 Robotnik With 1 Hit
  FFBA21:01
• Defeat Stage 7 Robotnik With 1 Hit
  FFBB21:01
• Defeat Stage 8 Robotnik With 1 Hit
  FFBC21:01
• Defeat Final Stage Bosses With 1 Hit
  FFB461:01
• Enable Super Sonic (All Chaos Emeralds Collected)
  FFFFB1:07
• Switch F/X On For Levitate Jump For Sonic
  FFB012:FE
• Switch F/X On For Levitate Jump For Tails
  FFB052:FE
• Hyper Mode P1
  FFB01E:00
• Hyper Mode P2
  FFB05E:00
• Sonic Color Modifier 6
  FFFB04:??
  FFFB05:??
  FFFB06:??
  FFFB07:??
  FFFB08:??
  FFFB09:??
  FFFB0A:??
  FFFB0B:??
• Sonic & Tails Sneaker Color Modifier (Base Color)
  FFFB19:??
  FFFB1A:??
  FFFB1B:??
• HUD Display Modifier 7
  FFF711:??
• Rings Multiplier 8
  FFF710:00
• Warp To End of Stage P1 9
  FFB008:3C
• Warp To End of Stage P2 10
  FFB048:3C
• Play As Super Sonic (No Powers)
  FFFE19:01
• Disable Water
  FFF730:00
• Glowing Sonic
  FFF65F:FF

Footnotes

• At the title screen, hold the A button and push Start to enter the stage select menu.
• This code also allows you to pass the special stages with ease, and always get the Chaos Emerald at the end.
• 00 – Emerald Hill
  01 – [glitch] Emerald Hill
  02 – [glitch] Emerald Hill
  03 – [glitch] Emerald Hill
  04 – Metropolis
  05 – Metropolis [3]
  06 – Wing Fortress
  07 – Hill Top
  08 – Hidden Palace (!)
  09 – [glitch] Emerald Hill
  0A – Oil Ocean
  0B – Mystic Cave
  0C – Casino Night
  0D – Chemical Plant
  0E – Death Egg
  0F – Aquatic Ruin

  Quantity Digits for “yy”(act):

  00 – Act 1
  01 – Act 2
  02 – Act 3

  Not all stages have acts 2 or 3.

• Switch effects off to collect rings.
• Switch effects off before you see the Sega logo to avoid freezing.
• The third, fifth, and seventh lines are optional.
• Also affects the rings. You can still collect them.

  00 – Off
  01 – On

• Cheesy, yet satisfying. Since the rings are loading over each other all the time, there is a major slowdown in the game speed.
• Turn off after you reach there.
• Turn off after you reach there.