Martial artists Billy and Jimmy Lee (or Hammer and Spike, as they were inadvertently renamed briefly in the U.S.) must rescue 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 Willy, the leader of the Black Warriors. The original arcade game also had an infamous Twist Ending: if two players clear the game, they must fight to the death for Marian's love.
The NES port was developed in-house by Technos and published outside Japan by Tradewest in 1988. Because Technos was inexperienced in developing NES games at the time (having only ported Renegade to the NES prior to it), the arcade game's popular co-op 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 matches due to memory limitations). The game's plot was altered to fit this change: Billy ventures out on his own to save Marian, and fight his own brother Jimmy, who is now the "Shadow Boss" of the Black Warriors. The level designs were changed to make the adventure longer than the arcade game, and it added a Character Level feature (the player earns experience points by beating up enemies, which allows Billy to gain new techniques as he levels up).
Other versions of Double Dragon were released for the Sega Master System, Atari 2600, 7800, Game Boy, Genesis, Lynx and various home computer formats with varying degrees of quality. Atlus released a remake, titled Double Dragon Advance, for the Game Boy Advance 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 iOS and Android devices; Brizo Interactive, who also handled the rarely-seen Zeebo version released only in Brazil and Mexico, developed this remake.
Double Dragon provides examples of:
- Adapted Out: Jack and Jeff (the mohawked Abobo and the evil Lee brother wannabe respectively) were cut from the NES and Game Boy versions of the game. Jeff does show up in the SMS version though.
- Adaptational Villainy: In the NES version, Jimmy went from being Billy's partner to being the "Shadow Boss" of the Black Warriors.
- After Boss Recovery: Defeat an end-of-mission boss to fully restore your life energy.
- The Artifact: The input for Jump Kicks in the arcade version is different depending on the direction the player is facing. The kick button only does jump kicks to the left, while the punch button is for jump kicks to the right. This is actually a leftover mechanic from when the game was conceived as a Renegade sequel, which featured directional based attack buttons.
- Artifact Title: The developers of the NES version managed to subvert this despite the lack of a two-player co-op. The title Double Dragon wouldn't have made much sense without both Lee brothers, so they turned one of them into a bad guy for the other to confront.
- The Game Boy version plays this straight though. It's strictly a solo adventure for Billy Lee, which ends after Willy is defeated without any sibling showdown afterward. There is a 2-player versus mode with both brothers, but it's nothing but a glorified minigame.
- Bald of Evil: Abobo.
- Boss Rush: In the arcade version, the player fights twin versions of Jack (the Mission 1 boss) before reaching the final hall where 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 (and Jimmy), one after the other.
- Canon Immigrant: Chin does not appear in the arcade game and was created for the NES port to replace Jeff's role. Chin was later added (and radically redesigned) for the arcade sequel.
- Character Level: The NES game added a leveling system that forced the player to use basic punches and kicks (and the headbutt) at the start of the game. As the player levels up Billy, new moves are unlocked.
- Composite Character:
- In the NES version, Jimmy Lee not only serves as the new final boss, but effectively replaces Jeff (the head-swapped Lee brother boss from the arcade version) as the player's evil counterpart.
- According to Japanese magazine articles when the arcade version came out, the Abobo variants originally had different names. The bald variant that serves as the elite mook is named Zack, the black mohawked head-swap who serves as the Mission 1 boss is named Jack, and his green-skinned palette-swap at the end of Mission 3 is supposed to be the real Abobo. On the NES version, Abobo has the design of Zack, the skin and outfit color of Jack and the name of the green-skinned giant
- The Computer Is a Cheating Bastard: In the NES version's Mode B, 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.
- Co-Op Multiplayer: Both the Arcade and NES versions subvert this in different ways.
- Damn You, Muscle Memory!: The NES version uses A+B as the command for a jump kick—when Billy has reached Level 3. Until then, A+B is a regular jump, not an attack. Forget this bit and you may jump right into a bad guy's punches.
- Damsel in Distress: Marian.
- Degraded Boss: This happens to Jeff in the arcade version and Chin in the NES version. In the latter, Chin 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.
- Demoted to Dragon: In the NES version, Willy goes from being the final boss to being the penultimate fight before the final battle with Jimmy.
- Direct Continuous Levels: 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. When 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 and Game Boy versions in particular opting to have different levels instead for each mission.
- Dual Boss: 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 Jacks 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.
- Every 10,000 Points:
- The arcade version, like most other games at the time, rewards you with extra lives based on the amount of points acquired depending on the machine's DIP switch settings. On the other hand, the NES version forces you to clear the game with no score-based extra lives whatsoever.
- The Master System and Game Boy versions give you an extra life for every 30,000 and 20,000 points, respectively.
- Evolving Attack: The NES version gives Billy new moves as he gains experience points from fighting enemies.
- Expy: The design of Chin, the enemy character exclusive to the NES and Game Boy version, resembles that of the Karate Fighter, an opponent from earlier Technos game Exciting Hour (aka Mat Mania).
- Head Swap: While Willy is completely unique, the rest of the bosses in the arcade version are recycled from other characters. Jack (the Mission 1 boss) is pretty much Abobo with a mohawk, and he reappears in Mission 3 with green skin, while Jeff (the Mission 2 boss) is an evil Lee brother.
- Kick Them While They Are Down: The NES version took a cue from Renegade and added a Sit-on Punch to Billy's attack repertoire, allowing him to pin down fallen enemy grunts and punch them while they're down. However, it does not work on stronger enemies unless they are close to dying, and it doesn't work on Jimmy or Abobo at all.
- Let's You and Him Fight: After defeating the final boss in the arcade version, Billy and Jimmy must fight to the death to see who wins the heart of Marian.
- Level Grinding: 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 have the patience, you can use that trick to earn the entire set of techniques by the end of Mission 1.
- Long Song, Short Scene: 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, which plays the track in the first area in Mission 4 (the mountain path to the Black Warriors hideout).
- Mirror Match: 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 mirror matches due to memory limitations. The Game Boy version features the same game mode (accessible via link cable), but only allows players to use the Lee brothers.
- The final boss of the NES version is Billy's brother, Jimmy. He has all the same moves, but he's much quicker and takes one hell of a beating before he does down.
- Named by the Adaptation: Subverted. Some of the characters were actually named when the arcade version was released, but this was only printed by certain publications (such as Famitsu and Beep) when the game was released in Japan. Since the Japanese flyer and instruction cards didn't have any character profiles on them, they were mostly unknown for a while until the game was converted to the Famicom/NES and had them listed in the manual. This also led to the two protagonists being inadvertently renamed "Hammer" and "Spike" for the game's U.S. promotional materials.
- Abobo was originally named Zack in Japanese magazine articles and his black mohawked counterpart was called Jack (misspelled Jick in Famitsu), Abobo being originally the name of the green-skinned variant of Jack at the end of Mission 3. However, the console versions cut all the mohawked variants of the character and kept only the bald design, naming him Abobo in the process.
- 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), while the Game Boy version makes reference of Jimmy's role as the Shadow Boss in the manual despite the actual game ending its single-player mode with Willy as the final boss without Jimmy showing up at all. The manual for the Genesis version is possibly the biggest offender in this instance, in which the author mistakenly assumed that Willy was supposed to be Jimmy himself.
- Non-Standard Game Over: If the two-player duel at the end of the arcade version ends in a Double KO (e.g. if both brothers fall into the spike pit), the game returns back to the title screen with no fanfare whatsoever.
- Obscured Special Effects: Willy and his gang take off on their bikes after abducting Marian in the arcade version. While players don't see the actual bikes on-screen, they do get to hear engines roaring after the Lee brothers leave their garage, and the sound is obviously not coming from their car.
- Over-the-Shoulder Carry: In the opening scene, Marian is knocked out and carried away by Willie's thugs. This would end up being a somewhat iconic scene for the franchise, as it would be shown again in many of the remakes and sequels throughout the years, such as Double Dragon Advance and Double Dragon Neon.
- Palette Swap: 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 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.
- Pistol-Whipping: Willy does this with his gun.
- Production Throwback:
- The end of Mission 1 in the arcade version has a billboard for Nekketsu Koha Kunio-kun, the Japanese version of Renegade, on the building just before the first boss battle.
- The red Interceptor from the cult laserdisc game Road Blaster is parked inside Billy and Jimmy's garage at the start of the first stage. Road Blaster was directed by Double Dragon creator Yoshihisa Kishimoto, who was employed by Data East prior to joining Technos Japan.
- Sequence Breaking: In the final area of the arcade version, Willy watches from a balcony and will come down once the Lee brothers have beaten enough of his thugs. You can bring Willy down earlier by intentionally letting Abobo throw you onto the balcony (which knocks Willy down).
- Shout-Out Theme Naming: Lead designer Kishimoto was influenced by the films of Bruce Lee and named the Lee brothers after him (Billy Lee was even named after Billy Lo from Game of Death). The two recurring enemy characters, Williams and Rowper, take their names from the other two main heroes in Enter the Dragon. Linda is named after Bruce's wife, Linda Lee Cadwell.
- Skippable Boss: The NES version has the first two bosses: Abobo and Chin. During the Abobo fight, you can knock him onto the edge of the conveyor belt, which he'll usually be too slow to get up from before being carried off into the bottomless pit. With Chin, you can just climb down the ladder used to reach him before he takes a single swing at you. He'll disappear without respawning, and the game will think you've defeated him.
- Spell My Name With An S: Williams' name is shortened to "Will" on the Mode B select screen in the NES, while Rowper's name is mistranslated as "Lopar" in almost all the localized manuals, which also has Chin Taimei's name shortened to "Chintai".
- Stalked by the Bell
- There Was a Door: In the first level of the arcade version, Abobo enters the screen by punching through a brick wall, despite the building having a door that other enemies use.
- Theme Music Power-Up: The title theme is played during the final battle againgst Willy.
- Unwilling Suspension: This happens to Marian in the arcade version. (In the NES version, she's resting on a bed.)
- Use Their Own Weapon Against Them: Certain enemies carry melee weapons, which can be knocked out of their hands and picked up to be used against them.
- Video-Game Lives: They'll be infinite in the arcade version if the machine's DIP switch settings are set to "Free Play".
- "Wanted!" Poster: In the arcade version, there are wanted posters of the first two bosses (Jack 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.
- You Have Researched Breathing: In the NES version, 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 simple ability to punch downward at enemies lying on the ground. All these things have to be learned from experience points acquired throughout the game.
