G:Double Dragon

C:Freeze The Timer Countdown|AAUNYLPA|Galoob|
C:Start Game With 1 Life|AEUTLZZA|Galoob|
C:Start Game With 6 Lives|IEUTLZZA|Galoob|
C:Start Game With 9 Lives|AEUTLZZE|Galoob|
C:More Energy For Player 2 Or The CPU|XTKNXEZK|Galoob|
C:More Energy For Player 1|XTKYOEZK|Galoob|
C:Timer Will Count Down Fast|AZUYZLAL|Galoob|
C:Timer Will Count Down Super-Fast|APUYZLAL|Galoob|
C:No Enemies|III000|Kristian Jarvis|
C:Enemies Will Not Fight Back|IIIEOO|StillANESFan|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. I was able to complete this game using this code and was never attacked once. No glitches, hang-ups or problems stopping your progess. A Great Code. Should have been included in the Codebook.
C:Slow Motion|KOTKOK|Daniel T|
C:Enemies And Billy Are Invisible|NOTZEY|Daniel T|
C:Psychedelic Music And Some Sound Is Messed Up|ANGEIS|Daniel T|
C:No Sound|ZOLAZO|Daniel T|
C:Flying Code|NAYZEY|Daniel T|Enemies fly away when killed. Billy may also fly away which is not good. Some enemies bounce. (Avoid getting enemies stuck in walls)
C:Enemies Are Stronger And Fall As If Falling Off A Cliff|NEYZEY|Daniel T|
C:Stronger Enemies (They Can Take More Punishment And Give It Back As Well)|PEYZEY|Daniel T|
C:Enemies Slowly Rise To Their Death|IIIZEY|Daniel T|
C:Only Punching Affects Enemies And Billy|GGGZEY|Daniel T|
C:What Happened To Billy!?|SIZZYY|Daniel T|
C:Billy And Enemies Fall Hard To The Ground When Knocked Down|POTZZY|Daniel T|
C:Billy Disappears When Hit And Reappears At A Different Location|EEIIOY|Daniel T|Some enemies disappear when killed, dynamite is useless.
C:Teleporting Billy!|GIPSSY|Daniel T|Enemies disappear at times. It is very hard to enter doors!
C:Gliding Billy|SISSSY|Daniel T|
C:Switches Places Of Energy, Time, Etc.|PIKKYY|Daniel T|
C:Enemies Are Easier To Kill And So Is Billy|UTTXXX|Daniel T|
C:Enemies Get Sucked Into The Air When Hit (Be Careful This May Happen To Billy As Well)|PTTXXX|Daniel T|
C:Infinite Lives|EEUTLZZE|electric_jimi|
C:More Energy For Player 1|TKYOEZK|Vampire Hunter X|
C:Mode A Much More Power|NYNLPE|PhilTheHammerRo|
C:Gain Hearts Very Quickly|VKKYXLVT|Tony Hedstrom|
C:Don't Gain Any Hearts|SXSNKLSA|Tony Hedstrom|
C:Stronger Lindas|ZUPPIL|Greg Olafurson|
C:Weaker Lindas|TEPPIL|Greg Olafurson|
C:Start With 2 Hearts, Start At Level 1 End Boss|PEXTIZAA|Greg Olafurson|
C:Start With 3 Hearts, Mid-Level 1|ZEXTIZAA|Greg Olafurson|
C:Start With 4 Hearts, Mid-Level 1|LEXTIZAA|Greg Olafurson|