The following are known Game Genie Codes for Double Dragon on Nintendo Entertainment System (NES).

• Freeze The Timer Countdown
  AAUNYLPA
• Start Game With 1 Life
  AEUTLZZA
• Start Game With 6 Lives
  IEUTLZZA
• Start Game With 9 Lives
  AEUTLZZE
• More Energy For Player 2 Or The CPU
  XTKNXEZK
• More Energy For Player 1
  XTKYOEZK
• Timer Will Count Down Fast
  AZUYZLAL
• Timer Will Count Down Super-Fast
  APUYZLAL
• No Enemies
  III000
• Enemies Will Not Fight Back
  IIIEOO
  Note: This code allows you to fight enemies without fear of retaliation. Be careful not to knock enemies outside of the screen as you will not be able to progress if they are still alive. Also, if you turn your back and walk away they sometimes will approach you and you can get them back on the screen that way.
• Slow Motion
  KOTKOK
• Enemies And Billy Are Invisible
  NOTZEY
• Psychedelic Music And Some Sound Is Messed Up
  ANGEIS
• No Sound
  ZOLAZO
• Flying Code
  NAYZEY
  Note: Enemies fly away when killed and Billy may also fly away which is not good as well as some enemies bounce.
• Enemies Are Stronger And Fall As If Falling Off A Cliff
  NEYZEY
• Stronger Enemies (They Can Take More Punishment And Give It Back As Well)
  PEYZEY
• Enemies Slowly Rise To Their Death
  IIIZEY
• Only Punching Affects Enemies And Billy
  GGGZEY
• What Happened To Billy!?
  SIZZYY
• Billy And Enemies Fall Hard To The Ground When Knocked Down
  POTZZY
• Billy Disappears When Hit And Reappears At A Different Location
  EEIIOY
  Note: Dynamite is also useless.
• Teleporting Billy
  GIPSSY
  Note: Enemies disappear at times and it is very hard to enter doors.
• Gliding Billy
  SISSSY
• Switches Places Of Energy, Time, Etc.
  PIKKYY
• Enemies Are Easier To Kill And So Is Billy
  UTTXXX
• Enemies Get Sucked Into The Air When Hit (Be Careful This May Happen To Billy As Well)
  PTTXXX
• Infinite Lives
  EEUTLZZE
• More Energy For Player 1
  TKYOEZK
• Mode A Much More Power
  NYNLPE
• Gain Hearts Very Quickly
  VKKYXLVT
• Don’t Gain Any Hearts
  SXSNKLSA
• Stronger Lindas
  ZUPPIL
• Weaker Lindas
  TEPPIL
• Start With 2 Hearts, Start At Level 1 End Boss
  PEXTIZAA
• Start With 3 Hearts, Mid-Level 1
  ZEXTIZAA
• Start With 4 Hearts, Mid-Level 1
  LEXTIZAA
• Gain A Heart Everytime You Hit An Enemy
  EKINNL
• Disable Level 4 Wall Trap
  NYZSIU
• Williams Has Half As Much Life
  TEAOIL
• Williams Has 1 Half Times As Much Life
  YEAOIU
• Williams Has Twice As Much Life
  IOAOIL
• Rowper Has Half As Much Life
  AEPPPL
• Rowper Has 1 Half Times As Much Life
  YEPPPU
• Rowper Has Twice As Much Life
  IOPPPL
• Linda Has Half As Much Life
  AEPPIL
• Linda Has 1 Half Times As Much Life
  YEPPIU
• Linda Has Twice As Much Life
  IOPPIL
• Chin Has Half As Much Life
  ZEPOPU
• Chin Has 1 Half Times As Much Life
  YOPOPU
• Chin Has Twice As Much Life
  AUPOPL
• Abobo Has Half As Much Life
  ZEPOIU
• Abobo Has 1 Half Times As Much Life
  YOPOIU
• Abobo Has Twice As Much Life
  ZXPOIU
• Willie Has Half As Much Life
  ZOZPPU
• Willie Has 1 Half Times As Much Life
  ZKZPPU
• Willie Has Twice As Much Life
  ANZPPU
• Jimmy (Final Boss) Has Half As Much Life
  ZUAOPU
• Jimmy (Final Boss) Has 1 Half Times As Much Life
  EKAOPL
• Jimmy (Final Boss) Has Twice As Much Life
  NNAOPU
• Enemies Duck 12% of The Time, Every 8 Seconds
  YOEUALLE
• Only 2 Hits Needed Before You Can Uppercut Enemies
  PAVUELZA
• Stage Select
  ?EXVGYAA
  ?AVNLGAA
  Modifiers
  • P: Stage 2
    P
  • Z: Stage 3 (1st Half)
    P
  • Z: Stage 3 (2nd Half)
    Z
  • L: Stage 4
    P
  • L: Ending
    Z
• Weapon Modifier When Picking Up A Weapon
  OXVXKEPX
  ?EVXSEYA
  Modifiers
  Note: These are graphically off at times.
  • A: Golf Club
  • P: Throwing Knife
  • Z: Whip
  • L: Dynamite
  • G: Barrel
  • I: Boulder
  • T: Box
• Gain A Heart For Every 100 Heart Points
  AOKNELEP
• When You Gain A Heart, The Heart Counter Resets To 900 Heart Points Instead of 0
  PEKNSLAE
• Defeat Enemies And Bosses By Knocking Them Down Once
  SLNPAXSO