Double Dragon II: The Revenge (NES)

Double Dragon II: The Revenge
Developer: Technos Japan Publishers: Technos Japan (JP), Acclaim Entertainment (US/EU/AU) Platform: NES Released in JP: December 22, 1989 Released in US: January 1990 Released in EU: 1990 Released in AU: 1990 This game has unused graphics. This game has unused text. This game has debugging material. This game has regional differences. This game has a prototype article

The Lee twins put their differences aside to take on a far deadlier foe, who quickly makes things that much more personal. This NES port brought back the co-op feature inexplicably missing from the first game, as well as some funnier-than-intended cutscenes. G - R - A - S - P !

Debug Features

There is a common debug feature in a couple of Technos games. Usually all debug code is controlled by a memory flag, hardwritten at the end of the ROM at address $FFF6 in M6502 CPU address space. Various bits of this variable enable or disable various debug features.

Sample Version

Bit 7 of the debug variable (to set it, use the Game Genie code EKNYVYAA) switches between normal and "SAMPLE VERSION", which enables some debug features. During the game, hold the Select button on Controller 1, then press one of the following buttons:

Up / Down: Gets rid of the nearest enemy on a particular side. B: Gets rid of all enemies on the screen. A: Instantly takes you to the next level.

Free Walk

Bit 5 of the debug variable (to set it, use the Game Genie code AXNYVYAA) enables free walk mode, which allows you to walk to any part of a level instantly.

Unused Graphics

Marian

There are three different sprite designs for Marian when she appears just before the final battle in Mission 9. The first one from the left is the one that is actually used in the game, while the other two are unused designs.

The manual for Double Dragon III: The Sacred Stones, which features a plot summary of the second game, for some reason uses a screenshot from an early version of the game in which one of Marian's alternate designs is used. The palette also appears to be different from the one used in the final game.

Unused Messages

There are unused text strings in both versions of the game for what appears to be early versions of the ending messages that you'll get when you complete the game on one of the lower difficulty settings in the English version. Apparently the WARRIOR difficulty was originally called NOVICE. There also appears to be a message for when completing the game on SUPREME MASTER (originally called simply MASTER), even though the final version of the game contains no similar message and simply plays the ending sequence. These can only be viewed during debugging.

(Source: CaH4e3)

Regional Differences

Title Screen

Japanese	English

"Acclaim presents" was added to the top of the English version's title screen, causing the logo itself to be moved a bit lower and a single line of copyrights removed.

Copyrights Screen

All the copyrights information have been moved to a different screen in the NES version, which is displayed just before going into the main menu.

Main Menu

Japanese	English

The difficulty settings are given much fancier names in the English version. Whereas in the Japanese version the choices are EASY, NORMAL and DIFFICULT, the English version instead goes PRACTICE, WARRIOR and SUPREME MASTER. The difficulty settings are also aligned horizontally in the Japanese version, allowing the player to move the cursor with the d-pad by pressing left or right, whereas in the English version this can only be done with select. The English version also has the full title of the game on top, whereas the Japanese version simply says "DOUBLE DRAGON" only.

HUD

Japanese	English

The HUD is four lines higher in the English version compared to the Japanese version, partially obscuring some of the scenery.

Difficulty Differences

• The Japanese version allows the player to go through all nine stages on any difficulty setting, whereas the English version restricts the game's length on the lower settings: PRACTICE ends the game on Mission 3, while WARRIOR ends on Mission 8, leaving Mission 9 accessible only on SUPREME MASTER.
• Continues are available by default in the Japanese version, whereas the English version requires the player to enter a cheat code at the GAME OVER screen that changes after every third stage. After choosing to continue, the player will be taken back to the main menu and will be allowed to change the number of players and difficulty setting before resuming at the last stage they left off. The length restriction will still be in effect after entering the continue cheat. This means that if the player lowers the difficulty level to PRACTICE on Mission 4 or above, the player will be warped back to Mission 3 instead. Likewise, lowering the setting to WARRIOR on Mission 9 will cause the player to continue the game on Mission 8 instead.
• Enemies seem to be more aggressive and have more health points in the Japanese version's DIFFICULT setting than they do in the English version's equivalent setting of SUPREME MASTER.

Easy	Normal	Difficult

• In the Japanese version, the disappearing platforms in Mission 6 will have different patterns depending on the difficulty settings: on EASY, all the platforms will appear at the same time; on NORMAL, only two platforms appear at a time; and on DIFFICULT, only one platform appears at a time. In the English version, the disappearing platforms always have the same pattern (one platform at a time), regardless of whether the game is set on WARRIOR or SUPREME MASTER. Normally, Mission 6 is unavailable on PRACTICE; however, if you cheat to access Mission 6 on that difficulty level, no platforms will appear, making the stage impossible to clear.

Cutscenes

The story sequences before each stage were originally written in English during the development of the game. In order to make room for the hiragana and katakana font sets, the majority of the images were rearranged within the CHR and reduced in size for the Japanese ROM, resulting in some (mostly subtle) differences between the two versions of the game.

Mission 1

Japanese	English

The final image in the opening cutscene of the English version is a shot of Billy Lee posing and yelling dramatically. This image is missing completely in the Japanese version. Instead, the Japanese opening ends with the image that comes before that, which is a closeup of Billy's eyes, but now the image is much wider, showing his temples.

Mission 2

Japanese	English

The English version has an extra blue line to the skyline above the helicopter and lacks the random gray tile at the upper left corner of the image in the Japanese version.

Mission 3

Japanese	English

The closeup of Billy on the first screen has more details in the English version (note the added hair and jacket on his shoulder) and a couple of pixels on the ladder shown on the third image are miscolored in the Japanese version. The image of the helicopter flying over the city on the second screen is wider in the Japanese version, but has less building variations (note the Empire State Building-like structure in the English version of the image missing in the Japanese version).

Mission 4

Japanese	English

The island, sea and helicopter have more details in the English version

Mission 5

Japanese	English

The image is a bit wider in the English version, adding extra details to the trees on the left and right side.

Mission 6

Japanese	English

The roof above the main gate is colored differently and some of the tiny columns in the middle portion of the temple are uneven in the Japanese version.

Mission 7

Japanese	English

The closeup of Billy's face is slightly wider and the background behind Marian has been recolored.

Mission 8

Japanese	English

There's extra bits of flesh-colored pixels next to Billy's mouth in the English version and Abore's hair was changed from blond to brown.

Mission 9

Japanese	English

An extra pixel tile next to the Mysterious Warrior's right shoulder (on our left side) is missing in the Japanese version.

Regional Leftovers

Both versions of the game contain a lot of disabled code leftovers from the other regional version. Although it is not possible to completely switch either version to another language mode, it is possible to switch between the two different sets of features in various places to change game behaviour between Japanese and US modes. Typically, the code pattern for such disabled code branches is A9 XX F0 which translates to the instructions "LDA #$XX" and "BEQ $", which means that the branch will always happen if XX is zero or always not happen in other cases. For the Japanese version, XX is all zeroes, while for the US version XX is $80. Since you can only disable some of the screens and modes in the US version with these codes, it's not very interesting. However, you can re-enable some things in the Japanese version that are different from the final US version.

Different Title Menu

The Game Genie code PENNGLAA re-enables an earlier version of the international title menu for the Japanese version of the game. It seems that the title for the game was going to be "Revenge of the Dragons" at some point. The Game Genie code AANNAIEA-AENNGLEA re-enables the Japanese version of the title menu for the international versions of the game.

Older title	Original title

Glitched Copyright Screen

The Game Genie code PAKNYAAA re-enables the copyright screen from NES versions of the game, but because of incorrect CHR bank settings, the text displayed becomes Japanese gibberish. You can decipher what was meant to be written by simply replacing the kana for the corresponding Roman character in alphabetical order (e.g. あううしあけす=ACCLAIM). Note that the screen in this version has different colors.

Difficulty Limits

The Game Genie code PEKOYGAA re-enables the difficulty limits in the Japanese version. Messages for both difficulties are mostly similar to the final US version, with two differences: 1) they call you "DRAGONS", instead of "DOUBLE DRAGONS"; and 2) the exclamation mark next to the phrase "GOOD LUCK" (!) has been replaced with a copyright symbol (©).