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

• Start With Infinite Lives
  SLAIUZ
• Keep Weapons After Losing A Life
  GXIIUX
• Become Invincible
  SLTIYG
• Start New Life With Machine Gun
  PEIIXZ
• Start New Life With Spread Gun
  LEIIXZ
• Start New Life With Laser
  GEIIXZ
• Start New Life With Fireball Gun
  ZEIIXZ
• P1 And P2 Start With 30 Lives
  IPVGZGZE
• P1 And P2 Have The 30 Lives Cheat Activated
  AAVGTGZA
• Activating The 30 Lives Cheat Gives You 99 Lives
  LTVKAKIP
• Weird Noise After You Die
  IPPOPO
• “You” Gun After You Die
  AEIIXX
• Less Normal Enemies That Show Up, And The Screen Is Invisibly Altered
  KONTAA
• Game Freezes When Bridge Starts To Explode
  NONEOK
• Stuck On The Very Left Side Of The Screen. Can Do Nothing But Shoot And Duck
  KISSIT
• Can’t Jump!
  POSSIT
• Flipping “Fall Down” Jump
  POTSIT
• Running Glitch
  PONSIT
• Flying Pods Fly Funny
  TSKTSK
• Stage Takes Longer To Start
  XEEGAG
• A Few Beeps After You Die
  IZPOPO
• One Beep After You Die
  ITPOPO
• Can’t Get Past The Title Screen
  LUCKYX
• The Ground Is One Step Lower Than It Should Be
  AGEKIP
• You Fall Thru Invisible Holes In The Ground
  KASTLE
• Scrambled Title Screen #1
  POIPIP
• Scrambled Title Screen #2
  SKILLX
• “Connecting” Music
  SIKETO
• The Guns In The Grey Boxes Look Funny
  AAAAGG
• Messes Up Sound And Pictures
  POTATO
• After You Die You Come Back With A Weird Gun
  TEIIXZ
• When You Die You Get An Extra Life
  NYAIUZ
• Each Stage Takes 5 Seconds Of Play
  LUGKIS
• No Gun After Death And Lots Of Baddies
  IEIIXZ
• Bubble Weapon And Lots Of Baddies
  TEIIXZ
• Disco Bee-Bob’N Mode!
  TOASTY
• I-Dare-You-To-Try-And-Beat-It-Like-This Mode
  PAIIXZ
• Double Cracker Gun Mode
  PEIIXY
• When You Walk, Your Legs Don’t Move
  STYSTY
• Sound Only when not Moving
  XXXAAA
• Alternate Music / Atari-Mode Contra
  NNNAAA
• When You Face To The Left You Slide Until You Hit The Side Of The Screen
  TSTSTS
• The Music Is Different
  KANETX
• Graphics Are Messed Up
  PPPETX
• Weird Music, And The Platforms On Level 1 Are Different
  APEAPE
• Colorful Lines Move Around On The Screen
  KOLKOL
• More Colorful Lines Move On The Screen
  AEEKOL
• 1st Level Is A Little Different
  SAGEPA
• You Can Only Shoot Straight
  PULUXU
• Standing Enemies Float, And Some Various Flashing
  NEPAEP
• Makes A Sound When You Die
  OPPOPP
• Strange Crash
  SXZGVK
• Tons Of Points For Shooting Enemies
  SXZGYK
• The Exploding Bridge Is “Camouflaged”
  XZYTLO
• Player 1 Starts With Laser Gun (Game Map Is Altered)
  XXLTLO
  XXGTLO
• 1st Boss Harder To Kill
  EPTILE
• When The Bridge Explodes, You Can Still Walk On It
  EOGKPN
• For A High Score, It Shows 200
  ZAOGEU
• Enemies Shoot At You More
  SPTAAN
• Weapon Capsules Fly By Slower
  OIKEAU
• Bullets Will Travel Thru Weaker Enemies
  KONVAL
• Your Bullets Will Auto-Hit Any Enemy
  KONTAK
• Kill Any Enemy Or Boss With 1 Shot (Except For Base 1 And 2 Bosses)
  KONTAL
• Extra Lives Are Awarded For Killing Most Enemies
  GITTEO
• Characters Can Walk On Water
  SLOVIA
• Removes Lifebar Indicators
  GOTGET
• Play Game In Black And White Mode
  OZNKTASX
  YPNKYEVN