History VideoGame / DoubleDragonI

Martial artists Billy and Jimmy Lee (originally Hammer and Spike in the arcade version) must rescue [[DamselInDistress their lady-friend Marian]] from the clutches of the Black Warriors, the dominant street gang of New York City. The Lee brothers must punch, kick, and jump their way through enemy forces across four stages to rescue her from the clutches of Machine Gun Willy, the leader of the Black Warriors. The original arcade game also had an infamous TwistEnding: if two players clear the game, they must fight to the death for Marian's love.

* AdaptedOut: The NES and Game Boy versions lacked the Mohawked Abobo and Lee Brother Knockoff that served as the boss characters in the arcade original.

* BossRush: In the arcade version, the player fights twin versions of the Mohawked Abobo (the Mission 1 boss) before reaching the final hall where Machine Gun Willy awaits. Willy fights alongside three clones of Jeff (the Mission 2 boss) after the initial batch of lackeys are defeated. In the NES version, the player fights a group of Williams and twin versions of all the other enemies (Abobo, Chin, Linda, and Rowper) before the final fight against Willy ([[spoiler:and Jimmy]]), one after the other.

* DualBoss: Both the arcade and NES versions reuse Abobo as a dual boss--specifically in the middle of Mission 3, where the player fights two of them either before crossing the bridge to the enemy's hideout (arcade) or before entering the cave through the holes both of them make (NES). The arcade version also includes a fight against two Mohawked Abobos before the final battle against Willy and his bodyguards, while the NES version includes another twin set of Abobos during the final rush to the end.

* HeadSwap: While Machine Gun Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission 1 boss is pretty much Abobo with a mohawk, and he reappears in Mission 3 with green skin, while the Mission 2 boss is an evil Lee brother.

* NamedByTheAdaptation: The Lee brothers, Marian and most of the Black Warriors gang were first given their names in the Famicom/NES version. The characters in the arcade version were originally nameless, outside the Hammer and Spike moniker that the two protagonists were given in the cabinets and flyers for the overseas version by Taito. Later conversions of ''Double Dragon'' (and even the liner notes of the official soundtrack) would keep the names established for the NES version.
** Since the two head swapped bosses were not featured in the NES version, they were initially not given any names. However, the evil Lee brother knockoff that served as the Mission 2 boss in the arcade version was named Jeff in the Master System version. The Mohawked version of Abobo on the other hand never gained an official name.

* NoCelebritiesWereHarmed: The Mohawked Abobo in the arcade version bears a strong resemblance to Creator/MrT.

* PaletteSwap: In addition to the Lee brothers themselves, the arcade version reuses the same small pool of enemies, changing only the color of their clothes and occasionally mixing in darker-skinned variants for each stage (the Green Mohawked Abobo at the end of Mission 3 is of special note). The only recurring enemy who keeps the same palette for every appearance is Linda.

* WantedPoster: In the arcade version, there are wanted posters of the first two bosses (the Mohawked Abobo and Jeff) in the very start of the game; each one has a bounty for $10,000. Willy's wanted poster is next to Jeff's in Mission 3; the bounty for Willy is $100,000--ten times greater than either of the other two.
* YouHaveResearchedBreathing: In the NES port, Billy Lee is a trained martial artist, yet he starts the game not knowing how to do some very basic moves, such as an uppercut, a roundhouse kick, or even the simply ability to punch downward at enemies lying on the ground. All these things have to be learned from experience points collected in-game.

* NonstandardGameOver: If the two-player duel at the end of the arcade version ends in a DoubleKO (e.g. if both brothers fall into the spike pit), the game returns back to the title screen with no fanfare whatsoever.

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The original '''''VideoGame/DoubleDragon''''' was originally released as an arcade game in 1987 (having begun development as a sequel for ''[[VideoGame/KunioKun Renegade]]''). Though not the first BeatEmUp, it was the genre's TropeCodifier, and its incredible popularity inspired numerous imitators in its day -- and beyond.

Other versions of ''Double Dragon'' were released for the MasterSystem, UsefulNotes/{{Atari 2600}}, [[UsefulNotes/{{Atari 7800}} 7800]], UsefulNotes/GameBoy, [[UsefulNotes/SegaGenesis Genesis]], [[UsefulNotes/AtariLynx Lynx]] and various home computer formats with varying degrees of quality. Creator/{{Atlus}} released a remake, titled ''Double Dragon Advance'', for the UsefulNotes/GameBoyAdvance in 2003; this remake integrated elements from the various sequels and console ports and also updated the combat system to more modern standards. In 2011, another remake (simply titled ''Double Dragon'') was released for UsefulNotes/{{iOS}} and {{Android}} devices; Brizo Interactive, who also handled the rarely-seen Zeebo version released only in Brazil and Mexico, developed this remake.

* ArtifactTitle: This is subverted by the NES version. The title ''Double Dragon'' wouldn't make much sense without the two-player co-op mode, so the developers turned one of the Lee brothers into the main bad guy so both of them would still be in the game.
** The Game Boy version lacks both the co-op mode and the final fight between the Lee brothers, but it still has the one-on-one "Mode B" minigame from the NES version, meaning that Jimmy Lee is still in the game (albeit [[DemotedToExtra in a limited capacity]]).

* DirectContinuousLevels: The entire arcade version takes place in one really long level until the end of Mission 3, when the player reaches the entrance of the enemy's hideout. Where the player defeats a boss at the end of each Mission, his character will simply walk to the next area in an automatic transition sequence. This detail was lost in most console versions of the game, with the NES version in particular opting to have different levels instead for each mission.

* HeadSwap: While Machine Gun Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission 1 boss is pretty much Abobo with a mohawk, and he reappears in Mission 3 with green skin, while the Mission 2 boss is an evil Lee brother. The NES version removed both of them.

** Because of the differences between the arcade and NES versions due to their slightly different character roster and Jimmy's role as an antagonist in the latter, some of the manuals for other conversions ended up adopting these discrepancies in their manuals by mistake. For example, the manual for the home computer ports all listed Chin Taimei (or Chintai, as his name was localized) as an enemy, despite those versions being based on the arcade game (where Chin never existed). The manual for the Genesis version is possibly the biggest offender in this instance, in which the author mistakenly assumed that Machine Gun Willy was supposed to be Jimmy himself.

* NamedByTheAdaptation: The Lee brothers, Marian and most of the Black Warriors gang were given their names in the Famicom/NES version. The characters were originally nameless in the arcade version, outside the "Hammer" and "Spike" moniker that the two protagonists were given in the cabinet and flyers for the overseas versions by Taito. Later conversions of ''Double Dragon'' (and even the liner notes of the official soundtrack) would use the names established by the NES version.
** Since the two head swapped bosses were not in the NES version, they were initially not given any names. However, the Mission 2 boss (the evil Lee brother knockoff), was later named Jeff in the Master System version. The Mohawked version of Abobo never had an official name.
** Because of the differences between the arcade and NES versions due to their slightly different character roster and Jimmy's role as an antagonist in the latter, some of the manuals for other conversions ended up adopting these discrepancies by mistake. For example, the manuals for the home computer versions list Chin Taimei (or Chintai, as his name was localized) as an enemy, despite never appearing in the arcade, while making references to the "Shadow Boss" (which was Jimmy Lee's title as the secret leader of the Black Warriors). The Genesis version is possibly the biggest offender in this instance: the author makes the mistaken assumption that Machine Gun Willy is supposed to be Jimmy Lee and ended up making a new identity to the Player 2 character instead.

* NamedByTheAdaptation: The Lee brothers, Marian and most of the Black Warriors gang were given their names in the Famicom/NES version. The game's characters were originally nameless in the arcade version, outside the "Hammer" and "Spike" moniker that the two protagonists were given in overseas promotional materials by Taito. Later conversions of ''Double Dragon'' (and even the liner notes of the official soundtrack) would use the names established by the NES version.

** Because of the differences between the arcade and NES versions due to their slightly different character roster and Jimmy's role as an antagonist in the latter, some of the manuals for other conversions ended up adopting these discrepancies by mistake. For example, the home computer versions listed the NES original enemy Chin Taimei (or Chintai, as his name was localized) in their manuals, which also made references to the "Shadow Boss" (Jimmy's title as the secret leader of the Black Warriors). The Genesis version is possibly the biggest offender in this instance: the author makes the mistaken assumption that Machine Gun Willy is supposed to be Jimmy Lee and ended up making a new identity to the Player 2 character instead.

* NamedByTheAdaptation: The Lee brothers, Marian and most of the Black Warriors gang were given their names in the Famicom/NES version. The game's cast were originally nameless in the arcade version, outside the "Hammer" and "Spike" moniker that the Lee brothers were given in overseas promotional materials by Taito. Later conversions of ''Double Dragon'' (and even the liner notes of the official soundtrack) would use the names established by the NES version.

** Because of the differences between the arcade and NES versions due to their slightly different character roster and Jimmy's role as an antagonist in the latter, some of the manuals for other conversions ended up adopting these discrepancies by mistake. For example, the home computer versions listed the NES original enemy Chin Taimei (or Chintai, as his name was localized) in their manuals and makes references to the "Shadow Boss" (Jimmy's title as the secre leader of the Black Warriors). The Genesis version is possibly the biggest offender in this instance: the author makes the mistaken assumption that Machine Gun Willy is supposed to be Jimmy Lee and ended up making a new identity to the Player 2 character instead.

* NamedByTheAdaptation: None of the characters were officially named in the arcade version, aside from the "Hammer and Spike" moniker that Taito America Corp gave to the protagonists for the [[http://flyers.arcade-museum.com/?page=thumbs&db=videodb&id=319 promotional flyer]] and [[http://images.marketworks.com/hi/60/60416/doubledragoncpo.jpg cabinet art]] ([[http://flyers.arcade-museum.com/?page=thumbs&db=videodb&id=1922 the Japanese flyer]] and [[http://gamengai.com/inst.html?type=inst&id=1659 instructions]] doesn't give out any names). Technos came up with the backstory and names of the characters for the [[http://www.gamengai.com/flyer.html?type=chirashi&id=512 Famicom version]] (as well as the liner notes for the [[http://vgmdb.net/album/5000 soundtrack album]]), but the head-swapped enemies were absent in this version and didn't get names at the time as a result. The head-swapped evil counterpart to the Lee Brothers would later be named "Jeff" in the [[http://www.smspower.org/Scans/DoubleDragon-SMS-JP-Manual?gallerypage=13 Mark III version]] though, leaving the mohawked version of Abobo as the only enemy [[NoNameGiven without an official name]] (as he was not in any of the console versions).
** Later licensed conversions of ''Double Dragon'' would use the backstory for the NES version while basing themselves on the arcade version, creating a few inconsistencies in the process. The manual for the home computer ports listed the NES-exclusive character Chin as an enemy and even includes references to the "Shadow Boss" (Jimmy Lee's title as the [[ManBehindTheMan secret leader]] of the Black Warriors) despite having him as one of the heroes. The manual for the Genesis version is possibly the biggest offender in this instance: the author makes the (wrong) assumption that Machine Gun Willy is Jimmy Lee and refers to the Player 2 character as Jake instead.

* HeadSwap: While Machine Gun Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission [=1=] boss is pretty much Abobo with a mohawk, and he reappears in Mission 3 with green skin, while the Mission 2 boss is an evil Lee brother. The NES version removed both of them.

* HeadSwap: While Machine Gun Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission [=1/3=] boss is pretty much Abobo with a mohawk, while the Mission 2 boss is an evil Lee brother. The NES version removed both of them.

* HeadSwap: While Machine Gun Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission 1 boss is pretty much Abobo with a mohawk, while the Mission 2 boss is an evil Lee brother. The NES version removed both of them.

The first ''VideoGame/DoubleDragon'' game was originally released as an arcade game in 1987 (having begun development as a sequel for ''[[VideoGame/KunioKun Renegade]]''). Though it was not the first BeatEmUp, it was the TropeCodifier, and its incredible popularity inspired many imitators that helped propelled the genre to new heights.

The premise is simple - martial artists Billy and Jimmy Lee (originally named Hammer and Spike in the arcade version) must rescue their lady-friend Marian from the clutches of the Black Warriors, the dominant street gang of New York City. Throughout four stages, the Lee brothers must punch, kick, and jump their way through enemy forces to rescue her. The original arcade game was also famous for its TwistEnding: if two players clear the game, they had to fight to the death for Marian's love.

The NES port, developed in-house by Technos and published outside Japan by Tradewest in 1988, is famous for its differing points. Since Technos was inexperienced in developing NES games at the time (having only ported ''Renegade'' to the NES prior to it), the popular [[CoOpMultiplayer two-player mode]] was omitted, replaced with a turn-based one and a "Mode B" one-on-one fighting mode where the player controls the Lee brothers or five enemy characters (with match ups being limited to {{mirror match}}es). The plot was also altered to fit this change: Billy ventures out on his own, and Jimmy is revealed to be the leader of Black Warriors. The level designs were also very different, making the adventure longer than its original arcade release, and it added a CharacterLevel feature - the player earn experience points by beating up enemies, allowing Billy to gain new techniques as he levels up.

Other versions of ''Double Dragon'' were released for the MasterSystem, UsefulNotes/{{Atari 2600}}, [[UsefulNotes/{{Atari 7800}} 7800]], UsefulNotes/GameBoy, [[UsefulNotes/SegaGenesis Genesis]], [[UsefulNotes/AtariLynx Lynx]] and various home computer formats with varying degree of quality. A remake was released by Creator/{{Atlus}} for the UsefulNotes/GameBoyAdvance in 2003 titled ''Videogame/DoubleDragonAdvance'', which integrated elements from the various sequels and console versions and updated the combat system to more modern standards. In 2011, another remake was released for UsefulNotes/{{iOS}} and {{Android}} devices simply titled ''Double Dragon'', which was developed by Brizo Interactive, who also handled the rarely seen Zeebo version released only in Brazil and Mexico.

!!This game provides examples of:
* AdaptationalVillainy: Jimmy Lee in the NES version, who went on from being Billy's partner to becoming the "[[TheManBehindTheMan shadow boss]]" of the Black Warriors.

* ArtifactTitle: Subverted by the NES version. The title ''Double Dragon'' wouldn't had made much sense without the 2P co-op mode, so what did the developers did to get around this conundrum? Just make one of the Lee brothers into the main bad guy so you could still have both of them in the game.
** The Game Boy version lacks both, the 2P co-op mode and the final fight between the Lee brothers, but it still has the one-on-one "Mode B" minigame from the NES version, meaning that Jimmy Lee is still in the game, albeit [[DemotedToExtra in a limited capacity]].

* BossRush: In the arcade version, the player fights twin versions of the Mohawked Abobo (the Mission 1 boss) just before reaching the final hall where Machine Gun Willy awaits, who fights alongside three clones of Jeff (the Mission 2 boss) after the initial batch of lackeys are defeated. In the NES version, the player fights a group of Williams and twin versions of all the other enemies (Abobo, Chin, Linda, and Rowper) just before the final fight against Willy ([[spoiler:and Jimmy]]), one after the other.
* CharacterLevel: The NES game added a leveling system that only allowed the player to use his basic punches and kicks (and the headbutt) at the start of the game, gradually giving him access to the rest of his moves as he levels-up.
* CompositeCharacter: Jimmy Lee in the NES version, who not only serves as the new final boss, but essentially replaces Jeff (the head-swapped Lee brother boss from the arcade version) as the player's evil counterpart.
* TheComputerIsACheatingBastard: In Mode B in the NES version, the computer has more health than you, can duck - which you can't do - and reacts faster than humanly possible when you run at it.
* CoOpMultiplayer: Famously subverted by the NES version.
* DamnYouMuscleMemory: The NES version uses A+B as the command for a jump kick--if your character has reached Level 3. Until then, A+B is just a regular jump, not an attack. Forget this bit, and you may jump right into a bad guy's punches.

* DegradedBoss: Happens to Jeff in the arcade version and Chin in the NES version. Chin in particularly appears as a mook at the beginning of Mission 3 almost immediately after the boss battle against him at the end of the previous stage.
* DemotedToDragon: In the NES version, Machine Gun Willy goes from being the final boss to simply being the last enemy Billy fights before the final battle with Jimmy.
* DualBoss: Both, the arcade and NES versions, reuse Abobo as a dual boss, specifically in the middle Mission 3, where the player fights two of them just before crossing the bridge to the enemy's hideout in the arcade version, and in the NES version just before entering the cave (through the holes both of them make). The arcade version also include a fight against two Mohawked Abobos just before the final battle against Willy and his bodyguards, while the NES version has another twin set of Abobos among the final enemy rush prior to the end.
* EveryTenThousandPoints: The arcade version, like most other games at the time, awards the player with extra lives based on the amount of points acquired depending on the DIP settings. The NES version on the other hand, forces one to clear the game with just the three lives Billy starts with.

* {{Expy}}: The design of Chin, the enemy character exclusive to the NES and Game Boy version, resmebles that of the Karate Fighter, an opponent from an earlier Technos game ''Exciting Hour'' (aka ''Mat Mania'').
* HeadSwap: While Machine Gun Willy (the final boss) himself is completely unique, the rest of the bosses in the arcade version are recycled from other characters. The Mission 1 boss is pretty much Abobo with a mohawk and reappears as the Mission 3 boss, while the Mission 2 boss is an evil Lee brother. The NES version removed both of them.

* LevelGrinding: The level-up system in the NES game awards players experience points based on the attacks they land on a foe. Since enemies only die when they're knocked to the ground, it's easy to leech off experience points by attacking an enemy without knocking him. If you're really patient, you can earn the entire set of techniques in this fashion by the end of Mission 1.
* LongSongShortScene: In both, the arcade and NES versions, the music that plays during stage transitions gets cut off before the full track is played. As a result, the only way to listen to the full intermission theme is through sound rips.
** The full track gets played in the Game Boy version, where it used as a background music for the first area in Mission 4 (the mountain path to the enemy's hideout).
* MirrorMatch: Mode B in the NES version is a one-on-one versus game that allows players to control the Lee Brothers or one of five enemy characters from the main game, but the battles are limited to same character matches (everyone is matched a palette swap of themselves). The Game Boy version features the same game mode as well accessible via link cable, but only allows both players to use the Lee brothers.

** Later licensed conversions of ''Double Dragon'' would use the backstory for the NES version while basing themselves on the arcade version, creating a few inconsistencies in the process. The manual for the home computer ports in particular would list the NES-exclusive character Chin as an enemy and even include references to the "Shadow Boss" (Jimmy Lee's title as the [[ManBehindTheMan secret leader]] of the Black Warriors), despite having him as one of the heroes. The manual for the Genesis version is possibly the biggest offender in this instance, where the author makes the wrong assumption that Machine Gun Willy is Jimmy Lee and refers to the Player 2 character as Jake instead.
* NoCelebritiesWereHarmed: The Mohawked Abobo in the arcade version bears a more than mild resemblance to Creator/MrT.
* NonstandardGameOver: If the 2-player duel at the end of the arcade version ends in a DoubleKO (say, if both brothers fall into the spike pit below), the game returns back to the title screen with no fanfare whatsoever.
* ObscuredSpecialEffects: Willy and his gang takes off on their bikes after getting a hold of Marian in the arcade version. While we don't see the actual bikes on-screen, we do get to hear the engines roaring off-screen after the Lee brothers leave their garage and it's obviously not coming from their car.
* OffModel: In the NES version, Jimmy Lee has blue hair instead of his usual blond in the opening sequence and his skin tone is much lighter as well. This was likely due to the NES' limited color display (it could only display up to 25 colors on-screen) -- the opening sequence is the only part of the game that has more than three characters (Jimmy, Marian, Williams, Rowper and Chin) on-screen at the same time.
* PaletteSwap: In addition to the Lee brothers themselves, the arcade version reuses the same small pool of enemies, changing only the color of their clothes and occasionally mixing in a darker skinned variants for each stage. The Green Mohawked Abobo at the end of Mission 3 is of special note. The only recurring enemy who keeps the same palette for every appearance is Linda (at least in the arcade version).
* PistolWhipping: Willy with his gun.

* SequenceBreaking: In the final area of the arcade version, Willy watches on from the balcony and will come down once the Lee brothers have beaten enough mooks. You can bring him down earlier by intentionally letting Abobo throw you up the balcony and knock him down.
* ShoutOutThemeNaming: Lead designer Kishimoto was influenced by the films of Creator/BruceLee and named the Lee brothers after him. Billy Lee in particular was named after Billy Lo from ''Film/GameOfDeath''. The two recurring enemy characters, Williams and Rowper, take their names from the other two main heroes in ''Film/EnterTheDragon'', while Linda is named after Bruce's wife Linda Lee Cadwell.
* SpellMyNameWithAnS: Williams' name is shortened to "Will" on the Vs. Mode's select screen in the NES and Rowper's name mistranslated as "Lopar" in almost all the localized manuals, which also shortened Chin Taimei's name to "Chintai".

* UnwillingSuspension: Marian in the arcade version. In the NES version, she's resting on a bed.
* WantedPoster: In the arcade version there are wanted posters of the first two bosses (the Mohawked Abobo and Jeff) in the very start of the game, with a bounty for $10,000 each. Willy's wanted poster can be see next to Jeff's in Mission 3, which shows that his bounty is $100,000, ten times greater than either of the other two.

* ObscuredSpecialEffect: Willy and his gang takes off on their bikes after getting a hold of Marian in the arcade version. While we don't see the actual bikes on-screen, we do get to hear the engines roaring off-screen after the Lee brothers leave their garage and it's obviously not coming from their car.

* DegradedBoss: Happens during the final two stages in both the arcade and NES versions, where the bosses from the first two stages appear as regular grunts. The "degraded" versions are generally just as tough and sometimes have just as much health as the boss versions.

* {{Foreshadowing}}: Jimmy Lee is among Marian's kidnappers in the opening of the NES version (instead of Machine Gun Willy like in the arcade version).
* HeadSwap: The boss characters in the arcade game. The Mission 1 boss is a black head-swapped version of Abobo with a mohawk, slightly larger eyes and a beard who could easily pass himself off as MrT, while the Mission 2 boss is a head-swapped Lee brother in green clothing.

* LetsYouAndHimFight: After defeating the final boss in the arcade game, Billy and Jimmy must fight ''to the death'' to see who wins the heart of Marian.

* LongSongShortScene: In both, the arcade and NES versions, the intermission theme played during stage transitions gets cut off before the full track is played. As a result, the only way to listen to the full intermission theme is through sound rips.
** The full track gets played in both, the Game Boy and GBA versions (where it is used as background music for one of the stages in the former version).

* OffModel: In the NES version, Jimmy has blue hair (and a lighter skin tone) during the opening sequence instead of the blond hair he has during the final battle. This was likely due to the NES' limited color display (it could only display up to 25 colors on-screen) and the fact that the opening sequence is the only part of the game that has more than three characters (Jimmy, Marian, Williams, Rowper and Chin) shown at the same time.
* PaletteSwap: The arcade version changes the palette for the enemy characters in each stage, with bad guys coming in white and black variants. The Mission 3 boss deserves a special mention, who is a green-skinned version of the Mohawked Abobo from the end of Mission 1, making one wonder whether the Black Warriors were experimenting with Gamma radiation.

* NoCelebritiesWereHarmed
** The Mohawked Abobo in the arcade version bears a more than mild resemblance to Creator/MrT.
** Williams and Rowper's sprite designs in the original arcade game were deliberately modeled after their namesakes from ''Film/EnterTheDragon''.

* EveryTenThousandPoints: The arcade version, like most other games at the time, awards the player with extra lives based on the amount of points acquired depending on the DIP settings. The NES version on the other hands, forces one to clear the game with just the three lives Billy starts with.

* BossRush: In the arcade version, the player fights twin versions of the Mohawked Abobo (the Mission 1 boss) just before reaching the final hall where Machine Gun Willy awaits, who fights alongside three clones of Jeff (the Mission 2 boss) after the initial batch of lackeys are defeated. In the NES version,, the player fights a group of Williams and twin versions of all the other enemies (Abobo, Chin, Linda, and Rowper) just before the final fight against Willy ([[spoiler:and Jimmy]]), one after the other.

* BadassMustache: Abobo's in-game sprite sported a horseshoe mustache. The concept art for the NES version gives Abobo a clean-shaved look though, making him look similar to [[VideoGame/GodOfWar Kratos]] or [[StreetFighter Sagat]].

* CompositeCharacter: Jimmy Lee in the first NES game, who not only serves as the new final boss, but essentially replaces Jeff (the head-swapped Lee brother boss from the arcade version) as the boss who uses all of the player's moves.
* TheComputerIsACheatingBastard: In mode B in the NES version, the computer has more health than you, can duck - which you can't do - and reacts faster than humanly possible when you run at it.

* DualBoss: The twin Abobos in the middle of Mission 3.
* EveryTenThousandPoints: Like most arcade games at the time, the number of extra lives awarded to the player varies based on the DIP switches. The NES version just forces you to beat the game with just three lives.

* {{Expy}}:
** [[http://www.gamengai.com/flyer.html?type=chirashi&id=512 The concept art]] for the Famicom/NES version makes Billy and Jimmy Lee look like clones of [[FistOfTheNorthStar Kenshiro and Raoh]].
** Chin Taimei from the NES game resembles the Karate Fighter from the Technos wrestling game ''Mat Mania''.

* PaletteSwap: The arcade version changes the palette for the enemy characters in each stage, with bad guys coming in white and black variants. The Mission 3 boss deserves a special mention, who is a green-skinned version of the Mohawked Abobo from the end of Mission 1. Were the Black Warriors conducting experiments with gamma radiation?

** Later licensed conversions of ''Double Dragon'' would use the backstory for the NES version while basing themselves on the arcade version, creating a few inconsistencies in the process. The manual for home computer ports in particular would list the NES-exclusive enemy Chin and even include references to the "Shadow Boss" (Jimmy Lee's title as the [[ManBehindTheMan secret leader]] of the Black Warriors), despite having him as a hero. The manual for the Genesis version is possibly the biggest offender in this instance, where the author makes the wrong assumption that Machine Gun Willy is Jimmy Lee and refers to the Player 2 character as Jake instead.

* MirrorMatch: Mode B in the NES version is a one-on-one versus game that allows players to control Billy Lee or one of five enemy characters from the main game, but the battles are limited to same character matches (Billy is matched against Jimmy, while the enemies are matched against a palette-swapped counterpart). The Game Boy features the same game mode as well accessible via link cable, but only allows both players to use the Lee brothers.