Mostly Unpublished NES Cheats ;)

red    marked cheats are unique, not listed on any site (tell me if not).
brown marked cheats from various other sources like gamefaqs.com etc, checked and fixed if necessary.
gray   marked disabled or missed cheats buried inside game ROM.

  Mad Max
  Magic Bubble, Mermaids of Atlantis, Bubble Bath Babes, Soap Panic
  Magic Candle, The
  Magic Darts
  Magic Jewelry
  Magic Jewelry 2
  Magic John, Totally Rad
  Magic Johnson's Fast Break
  Magic Mathematics (Sachen)
  Magical Taruruuto-kun - Fantastic World!!
  Magician
  Magnum Kiki Ippatsu - Empire City - 1931
  Mahjan Samit Kabukicho Hen (Sachen), Mahjong World (Sachen)
  Mahjang Companion (Sachen)
  Mahjong Academy (Sachen)
  Mahjong Club - Nagatachou
  Mahjong RPG Dora Dora Dora
  Mahjong Taikai
  Mahjong Taisen
  Mahou no Princess Minky Momo - Remember Dream
  Majaventure - Mahjong Senki
  Major League Baseball
  Majou Densetsu II - Daimashikyou Galious
  Maniac Mansion (Japan)
  Mappy
  Mappy Kids
  Mappy-Land
  Marble Madness
  Mario & Yoshi, Yoshi, Yoshi no Tamago
  Mario is Missing!
  Mario Open Golf, NES Open Tournament Golf
  Mario's Time Machine!
  Marvel's X-Men, Uncanny X-Men, The
  Mashin Eiyuu Den Wataru Gaiden
  Masuzoe Youichi - Icchou Made Famicom
  Matsumoto Tooru no Kabushiki Hisshou Gaku
  Matsumoto Tooru no Kabushiki Hisshou Gaku 2
  Mechanized Attack
  Mega Man, Rockman
  Mega Man 2, Rockman 2 - Dr. Wily no Nazo
  Mega Man 3, Rockman 3 - Dr. Wily no Saigo!
  Mega Man 4, Rockman 4 - Aratanaru Yabou!!
  Mega Man 5, Rockman 5 - Blues no Wana!
  Mega Man 6, Rockman 6 - Shijou Saidai no Tatakai!!
  Meiji Ishin
  Meimon! Dai San Yakyuu Bu
  Meimon! Takonishi Ouendan - Kouha 6 Nin Shuu
  Meitantei Holmes - Kiri no London Satsujin Jiken
  Meitantei Holmes - M Kara no Chousenjou
  Melville's Flame
  Menace Beach
  Mendel Palace, Quinty
  Metal Fighter, Mei Loi Siu Ji (Sachen / Kinema Music / Color Dreams), Wei Lai Xiao Zi (Joy Van)
  Metal Flame Psybuster, Metal Mech - Man & Machine
  Metal Max
  Metal Slader Glory
  Metroid
  Mezase Pachi Pro - Pachio-kun
  Mezase Top Pro - Green ni Kakeru Yume
  MiG 29 - Soviet Fighter
  Michael Andretti's World Grand Prix, Nakajima Satoru - F-1 Hero
  Mickey Mania, China Rabbit Baby
  Mickey Mouse, Mickey Mousecapade
  Micro Machines
  Might and Magic
  Mike Tyson's Punch-Out!!, Punch-Out!!
  Millionaire (Sachen)
  Mindseeker
  Minelvaton Saga
  Miracle Ropit's Adventure in 2100
  Mirai Senshi - Lios
  Mirai Shinwa Jarvas
  Mission Impossible
  Mito Koumon - Sekai Manyuu Ki
  Mitsume ga Tooru
  Mo Jie Ba Zhu (Nanjing, NJ079), Mo Jie Ta Shi (Nanjing)
  Moai-kun
  Mobile Suit Z Gundam - Hot Scramble
  Moero TwinBee - Cinnamon Hakase wo Sukue!, Stinger
  Momotarou Densetsu
  Momotarou Densetsu Gaiden
  Momotarou Dentetsu
  Money Game, The
  Money Game 2 - Kabutochou no Kiseki, The
  Monster In My Pocket
  Monster Party
  Monster Truck Rally
  Moon Crystal
  Moon Ranger
  Morita Kazuo no Shougi
  Mortal Kombat II/III Special (JY)
  Mortal Kombat V (YOKO)
  Motocross Champion
  Mottomo Abunai Deka
  Mouryou Senki Madara
  Ms. Pac-Man (Namco)
  Ms. Pac-Man (Tengen)
  Muppet Adventure - Chaos at the Carnival
  Musashi no Bouken
  Musashi no Ken - Tadaima Shugyou Chuu
  Mutant Virus, The
  My Life My Love - Boku no Yume - Watashi no Negai

Cheats summary:
generic cheats-19
unique cheats-109
buried secrets-44
fixed generic cheats-18
unverified games-0
games with secrets-102
games with no secrets found-47

Mad Max

(FIX) Secret passwords:
MMAX-Start at Arena 1
WAST-Begin Road war 2
BLAS-Start at Arena 2
MAEL-Begin Road war 3
HUMU-Start at Arena 3

Magic Bubble, Mermaids of Atlantis, Bubble Bath Babes, Soap Panic

Early versions:

(UNI) Level select (added 23.04.10):
Start a new game, while the "STAGE x-x" message is displaying on the screen, press Start to pause the game, then press Up, Right, Down, Left. From now you can change the level and sublevel numbers by pressing B and A accordingly. Press Start to end level editing, then press Start again to unpause and begin to play from the selected level.

Later versions:

(UNI) Ending sequence (added 15.01.08):
At the title screen, press Select then press Up, Up, Down, Down, Left, Left, Right, Right, A, A, B, B.

Magic Candle, The

(UNI) Sound test and debug mode (added 27.06.14):
Hold Up + Right + A + B on controller 2 and Up + Right + A + B + Select + Start on controller 1 then press Reset. Use Left or Right on controller 1 to select music and Left or Right on controller 2 to select sounds. Press any other buttons to exit back to the game. This cheat additionally enables the debug mode. Now, during the travel mode, on controller 2 press A to add 1000 gold, press B to advance to the next level. Additionally, when you start a new game, before exit the name entry screen, hold one of the following buttons on controller 2 to start from corresponding chapter:
A-Chapter 1
B-Chapter 2
Right-Chapter 3
Left-Chapter 4
Up-Final Chapter

(BUR) Hidden text (added 27.06.14):
The RESET routine in this game uses part of the string
M.C. (FC)  BY P.CHAN (JST)
to initialize its SRAM data.

Magic Darts

(UNI) Program version:
Hold Select at the "SELECT YOUR GAME!" menu until message "VERSION 01.02" appears.

(UNI) Secret message:
At the title screen, hold A + B, press Start to enter "SELECT YOUR GAME!" menu, do not release A + B and hold additionally Select until message "BY K1 NAKANISHI" appears.

(FIX) Secret words (added 05.01.14):
All secret names are enables the same weird hidden character, some names will be changed upong entering. Most probably, there must be more hidden secret characters, but only three left, one playable with different graphics, and two glitchy, utilizing already used graphics and can't be selected without hacking. There are 5 secret names total: "EBE", "SEX", "RNG", "MTY" and "TAD". The name "SEX" will change to "EBE" upon entering, the name "TAD" will change to "DAT". There is no more different effects to any of these names.

(BUR) Sound debugger (added 25.10.08):
There was "FAMICOM SOUND DEBUGER" mode at the development stage in this game, similar to the one from the "Silva Saga" game. But as against it, this debugger code wasn't much broken but still haven't any cross-refrences from the code and not working at all.
0000CCD0: D8 CC 46 41 4D 49 43 4F 4D 20 53 4F 55 4E 44 20 ..FAMICOM SOUND
0000CCE0: 44 45 42 55 47 45 52 00 A2 EC A0 CC 8E 36 00 8C DEBUGER......6..
0000CCF0: 37 00 A2 20 A0 66 20 24 F0 4C FB CC 4D 4D 43 31 7.. .f $.L..MMC1


Magic Jewelry

(UNI) Easter egg (added 17.03.14):
At the game over screen, hold Right + Select then press Start to see the developer's logo screen.

Magic Jewelry 2

(UNI) Easter egg 1 (added 17.03.14):
Hold Up + A + Select on controller 1, then press Reset, to see the developer's name "Hwang Shinwei" in chinese.
Source: BMF54123

(UNI) Easter egg 2 (added 17.03.14):
At the second title screen (with a player number selection), any time during the game, hold Down + Left + A on controller 1 and press Select to see the publisher company logo.

(UNI) Easter egg 3 (added 17.03.14):
At the second title screen (with a player number selection), only after the setup screen, hold Up + A + B + Select on controller 1, then press Start to see the full publisher logo and company name both in english and chinese.
Source: BMF54123

Magic John, Totally Rad

(GEN) Credits:
At the title screen, press Left, Left, Right, Up, Down, Down, Up on controller 2 then press Start on controller 1.

(GEN) Level select and Sound test:
At the title screen, press Up, Down, Down, Left, Left, Right, Right, Start on controller 1.

Magic Johnson's Fast Break

(BUR) Debug monitor (added 30.06.14):
During game, set the RAM address $2C to value $80. This enables the debug display at the top corner of the screen.

(BUR) Hidden text (added 02.12.08):
This game using for padding some info about developers.
 FAST BREAK     1989
     PROGRAMMER   KEVIN EDWARDS
     ARTIST       MARK WILSON
     MUSICIAN     TIM FOLLIN
  SOFTWARE CREATIONS LTD
FIRST FLOOR    204 OXFORD ROAD
MANCHESTER    M1 5QA
GREAT BRITAIN
TEL 061 236 1154
FAX 061 236 824


Magic Mathematics (Sachen)

(UNI) Secret message (added 07.04.10):
Start a new game in any mode, after the current question is written on the screen and programm is waiting for your answer, press Up, Up, Up, A, A, A, Down, Down, Down, B, B, B, Left, Left, Right, Right on controller 2 . A secret copyright message will appear.

Magical Taruruuto-kun - Fantastic World!!

(BUR) GameGenie (added 05.12.13):
PENNONNY-Re-enables some debug features, like invulnerability. Also, press A on controller 2 to skip current level. By pressing Up or Down on controller 2 increase/decrease items number in your inventory between levels.
AENNONNY-Similar to the previous one, but instead of invulnerability, you'll obtain 16 bags, 64 lives and some other parameters at the game start.

(BUR) Hidden text (added 05.12.13):
The RESET routine in this game should use the string
Yoshikawa
to check if game was soft or hard reset. Instead, the game only writes first two bytes of this sting to the RAM and never checks it.

Magician

(FIX) Spells:
PHOLRA-Razor
PHRAST-Axor
PHNAHU-Boomeraxe
PHRANA-Boulder
PHOLMIRA-Spear
VENAHUNARA-Ven
FISTMIRA-Fireball
FIRANAOLHU-Firestorm
FIOLNARAST-Fire ring
FIOLHUNARA-Fire spray
POHUNAST-Dispell
PONASTRANA-Lightning
POOLMISTNA-Repellent
POHURANAHU-Exorcise
POSTRAMIST-Death ring
PORAOLHUST-Psychic
MIOL-Help
MIFISTHURA-Meditate
MIRANARAST-Fly
MIRAHUFINA-Jump
PHRANARAHU-Phys Shield
VERANAMIST-Ven Shield
FIRANAHUNA-Fire Shield
PORANASTRA-Pow Shield
MINARA-Reveal
MIMIFINAST-Fleet Foot
MIMIRAHUNA-Slowmo
MISTRAOL-Featherlite
MISTNAST-Iron Boots
MINASTOL-Wakey Wakey
MIOLST-Light
MIRAHUOL-Translate
MINAOLNA-Twin
NAHUMISTMI-Sound test
HUHUMIHUHU-Who's Who (game credits)

Magnum Kiki Ippatsu - Empire City - 1931

(UNI) Secret passwords (added 05.12.13):
8E3B, A57D-Level select and invincibility. Select "CONTINUE" option, enter the first password, press Start, repeat with second password. Now, at the main menu, press A to increase level number up to 5, press B to increase sublevel number up to 8, press Start at the "START" option to begin game from selected level with invincibility.

(UNI) Password generator (added 05.12.13):
Stage:
Random:
Password:


Mahjan Samit Kabukicho Hen (Sachen), Mahjong World (Sachen)

Sachen-Hacker version:

(UNI) Tile select (added 07.04.10):
At the opponent selection screen, press A, A, B, Right, A, Left, B, Down, A, Up, then start a new game. During the game, press A to enable the tile select mode, press Up or Down to select a tile, press B to pick selected tile. The "Sachen"-only version of this game still checks for this cheat at the adult warning screen (third game option), but does nothing, even if you enter the correct code. The "Sachen-FC" version have this cheat completely removed.

Mahjang Companion (Sachen)

All versions:

(UNI) Tile select (added 07.04.10):
At the opponent select screen, press A, A, B, Right, A, Left, B, Down, A, Up, then start a new game. During the game, press A to enable the tile select mode, press Up or Down to select a tile, press B to pick selected tile.

Sachen version:

(UNI) Easter egg (added 07.04.10):
During the game, at the player's turn, press A, A, B, Right, A, Left, B, Down, A, Up on controller 2. Note, that this easter doesn't work if you enter the "Tile select" cheat first.

Mahjong Academy (Sachen)

(UNI) Slideshow (added 30.06.14):
At the opponent selection screen, hold Select + Start on controller 2 and Select on controller 1 at the same time, then press Start on controller 1.

Mahjong Club - Nagatachou

(UNI) Autoplay menu (added 01.07.14):
In any game mode, using the 4-Player adaptor for the Famicom, during the opponents turn, hold Up + Down + B on Controller 3 for a short time, then release the buttons. A menu with two options will appear, first option allows you to open all players tiles, the second option enables the autoplay mode, where all players including you will be CPU controlled.

(UNI) Extra Pts and points (added 01.07.14):
In the main game mode (first menu option), after every round you can trade some Pts in the special Shop for tickets. When asked, if you want to buy tickets, select "Yes" and press A, then immediately hold Up + Down + B on Controller 3, using the 4-Player adaptor. If done right, when the Shopkeeper appears, you'll get 300000 Pts and 270 tickets, and you can play the final round against most skilled players.

(BUR) Hidden text (added 01.07.14):
At the end of every 128K data block a some copyright and version text exist:
NAGATA 90/01/16=1.00R


Mahjong RPG Dora Dora Dora

(UNI) Tile select (added 05.12.13):
During mahjong battles, while selecting tile to discard from hand, hold A or B on controller 2 then press Select on controller 1 to change the rightmost tile to any you need.

Mahjong Taikai

(UNI) Cheat mode (added 01.07.14):
At the title screen or at the KOEI copyrights, hold Down + A + B on controller 2, then press Select on controller 1. This will set your level to 7 before the game. When you select to save the game, all players will obtain $9,999, including you, and you can continue the game. During the game, press Select and using the D-Pad buttons change any tile in your hand to any other. Enter the game menu and press Select to view the opponent's tiles.

Mahjong Taisen

(GEN) Sound test:
Hold Down + B + Select and press Reset. The screen should stay black. Use Up or Down to scroll through the music.
Source: ReyVGM

(GEN) Skip the intro:
Before starting a new game at the title menu, hold Right + A + B on controller 2.
Source: ReyVGM

(UNI) Faster animations (added 01.07.14):
Every screen transition in this game fades-in and fades-out the display with some speed. If you hold at least one of A or B or any D-Pad buttons on controller 2, the display will fades 4 times faster during screen stansitions. Additionally, B on controller 2 will speed up some cutscene animations during the game or the intro.

(UNI) Clear game statistic (added 01.07.14):
Every mahjong round, the game collects some info about number of rounds played, points won and other statistic. This statistic will be saved until the battery on cartridge is dead, no matter if you save or load other games, or start a new one. However, you can clear this statistic. Just before starting a new game at the title menu, hold Right + B + Start on controller 1. Unfortunately, there is no use of this statistic in this game at all, so itself it's useless.

(FIX) Secret words:
Enter one of the following words as a player name.
にちぶつ-Extra 200 EXP at start.
いさぽん-Extra 1000 EXP at start.
Source: ReyVGM

(BUR) Hidden text (added 01.07.14):
The SRAM and RAM initialization strings in this game are:
NihonBussan'92
and
@1988 Nichibutsu


Mahou no Princess Minky Momo - Remember Dream

(UNI) Secret passwords (added 02.06.14):
おねかいーきいて♥-Start a new game with all minigames enabled at the Game Center, including the final boss minigame, which is normally can't be accesible there and replaces the Fortune Teller minigame.

Majaventure - Mahjong Senki

(UNI) Cheat menus:
At the title screen, press Select to highlight the "CONTINUE" menu option. Hold Up + Select (the menu cursor should return back to the "START" option) and press Start to enter the stage select menu. Hold Select again and press Start to enter the enemy select menu, and finally hold Select then press Start to enter the sound test menu.

(GEN) Debug mode:
In the map mode, hold Right + B on controller 2 to freely pass through the gates and enemies. While in a fight, hold Left on controller 2 and enter and exit back from the status screen to see the opponent's tiles.
Source: ReyVGM

Major League Baseball

(FIX) Autoselect teams:
At the title screen, hold Down + Left + A + B + Select and press Start. The extra options will appear at the player select menu: "1 Player Set" and "2 Player Set". Select one of them, to automatically setup all teams by the CPU.

Majou Densetsu II - Daimashikyou Galious

(UNI) Password generator (added 23.12.07):
Bytes 0-3:
Bytes 4-7:
Bytes 8-B:
Bytes C-F:
Bytes 10-13:
Note:bytes $00, $04, $10 are decimal numbers, each octet not greater than 9.
Random:
Password:


Maniac Mansion (Japan)

(UNI) Move the head (added 05.01.14):
During the game, on controller 2, hold B and press the D-Pad buttons to move the main character's head to the corresponding direction.

(UNI) Secret passwords:
おわりをみたい
おわりをみたい
おわりをみたい
-Ending sequence
しらとまなふ-"mattakuu" message
おわひ-"password ga nagaku de sumimasen" message
RESET-Reset NES system
せたかやくようか-"JALECO" message
JALECO-"jibun no tikara de tokou ne" message
よいおとかかたいなあ-Sound test

Mappy

(BUR) Hidden text (added 08.02.13):
There is a hidden copyright text at the start of the PRG ROM and the same one a the end of the CHR ROM:
COPYRIGHT 1983 1984 NAMCO LTD.ALL RIGHTS RESERVED


(BUR) GameGenie (added 03.07.14):
GASSYNGK-Re-enables the invulnerability cheat. At the title screen, press A or B to toggle the invulnerability. An "N" letter at the center of the screen will indicate that invulnerability is enabled.

Mappy Kids

(UNI) Cheat options (added 03.07.14):
The cheats in this game tested in a very odd way. Instead of just checking the button combinations, pressend on any Controller, this game is counting the time how long you hold corresponding button. The combination of buttons held and how long they are held will trigger some effects. You can hold these buttons in any order or simultaneously, but only while the title screen is displayed, before the demonstration start, then press Start on controller 1. There are total 4 counters and 4 corresponding buttons. A complete list of combinations and timings for each button described in the table below.
Hold B on controller 2 for a 3-4 seconds (value between $3C and $78)
Hold Select on controller 1 for a 4-5 seconds (value between $78 and $B4)
Hold A on controller 2 for a 5-7 seconds (value between $B4 and $F0)
-Sound test
Hold A on controller 2 for a 4-5 seconds (value between $78 and $B4)
Hold B on controller 2 for a 5-7 seconds (value between $B4 and $F0)
-Level select
Hold Select on controller 1 for a 5-8 seconds (value between $B4 and $FF) in addition to the Level select buttons-In addition to Level select, this adds an 765000 yen to each player.
Hold B on controller 1 for about 4 seconds (value between $5A and $78)-Extra 20 lives both for 1 or 2 Player modes

Mappy-Land

Japanese version:

(UNI) Stage select:
At the title screen, press Up, A, Down, B, Left, A, Right, A, Select + Start.

(BUR) GameGenie (added 04.07.14):
LVXZGAZA-At the title screen, hold A + B on controller 2, then press Start. There were an Extra lives cheat, but in the final release the number of lives given is the same as default, so there is nothing happens. With this code you can re-enable the lives cheat with Extra 99 lives.
GAVYNTEI-There are series of the Namco games, made by the same programmers Haruhisa Udagawa and Kumi Hanaoka, that contains the same self-test for the data integrity. To enable any of these tests you need a special device that should be plugged into the expansion port. The operation of that device is very simple. It should accept the data bit from the data input port and return it back inverted to the output data port. The device consists of 4-bit shift register, working as some sort of the FIFO buffer. The input bits are goes to the input and then shifted to te output after a 4 cycles. At the game's boot, it tries to send some special data to the device. If the data output doesn't match the data input inverted, then the game continues the normal operation. But if all data (usually 32, rarely 64 bytes) is matches, self-tests will be performed. The program calculates 24-bit partial checksums for the PRG (excluding the last 8K) and the CHR data, summing only every 15th byte, and comparing it against the etalon. Before testing of the PRG data, the background color turns red, before testing of the CHR data, it turns green. If any of these tests are failed, the program will jump directly to the reset routine. It means, one of these tests will be performed infinitely, but until the special device is plugged in, or until the test are passed. Normally, you'll see the red to green flash just before the game's boot. Or the static red screen if the PRG data is bad, or the flashing red to green screen if CHR data isn't good. Using this Game Genie code you can skip tests for the special device presence and jump straight to the integrity tests.

US version:

(BUR) GameGenie (added 04.07.14):
LVXXZAZA-At main game menu, hold A + B on controller 2, then press Start. There were an Extra lives cheat, but in the final release the number of lives given is the same as default, so there is nothing happens. With this code you can re-enable the lives cheat with Extra 99 lives.

Marble Madness

(BUR) Hidden text (added 20.10.12):
Every PRG bank in this game contains a particular copiright strings in the US version:
(C) COPYRIGHT 1988 RARE LTD. ENGLAND.
and
PAUL.P & RACHEL.M.E
and only one string in the European version:
(C) COPYRIGHT 1990 RARE LTD.
The initials stands for Paup Proctor and Rachel M. Edwards.

Mario & Yoshi, Yoshi, Yoshi no Tamago

English versions:

(UNI) Soft reset (added 04.07.14):
Any time during game press A + B + Select + Start on controller 1.

Mario is Missing!

(UNI) Password generator (added 06.12.13):
New York complete
Rome complete
Syndey complete
San Francisco complete
Tokyo complete
Paris complete
Montreal complete
Moscow complete
London complete
Buenos Aires complete
Mexico City complete
Cairo complete
Nairobi complete
Beijing complete
Random
Password:


Mario Open Golf, NES Open Tournament Golf

All versions:

(GEN) Credits (added 06.12.13):
At the title screen, hold Right + B + Select for a couple of seconds.
Source: ReyVGM

Japanese version:

(UNI) Continue (added 06.12.13):
Start a new "STROKE PLAY" game. When asked to confirm the game select ("YES" or "NO") hold A + B on controller 2. The game will continue from the last played match.

Mario's Time Machine!

(UNI) Password generator (added 06.12.13):
80m B.C. complete
776 B.C. complete
31 B.C complete
1192 complete
1520 complete
1602 complete
1687 complete
1862 complete
1879 complete
1903 complete
1905 complete
1947 complete
1969 complete
1989 complete
Random
Password:


Marvel's X-Men, Uncanny X-Men, The

(FIX) Final stage (added 16.04.15):
Beat the first four regular levels. Every level ends with a message. Every message has some special words. To reveal these words, beat more than 30 special enemies on the stage and specific letters will be displayed in red color. Combining them will reveal a secret message: "The last mission can be reached from the mission screen by pushing Select and seek the advice of the label to make it to the final mission." Code written on the label is Up + B + Start, so you must press Up + B + Select + Start to reveal a secret final stage. Need to mention, that main part of the code (B + Select + Start) should be entered on controller 1. But you may press Up either on controller 1 or controller 2, doesn't matter.
Source: tcrf.net

Mashin Eiyuu Den Wataru Gaiden

(BUR) Secret names (added 04.07.14):
デバッグ-The debug leftover secret name ("DEBUG"), normally can't be entered at the name entry screen, because it's in different kana type. If you hack it somehow, the debug mode will be enabled. This will disables the cutscene and script scenes, as well as random encounters. Also gives you complete set of unlimited magic. Hold B during game to free move throught any obstacles.

Masuzoe Youichi - Icchou Made Famicom

(UNI) Script debug (added 07.12.13):
During the game, hold A on controller 2, then press Up, Up, Down, Down, Left, Right, Left, Right on controller 1. Two numbers will appear, the first one is a chapter number, the second one is current event number. When you advance in the game, this number will increase.

Matsumoto Tooru no Kabushiki Hisshou Gaku

(FIX) Secret words (added 05.01.14):
Enter as a player name:
あんごうぱす-Password screen.
Enter "0" exactly 100 times for the secret message.
おんがく-Does nothing, seems disabled sound test.
ぴくちゃー-Picture test.
くれじっと-Credits.
Source: ReyVGM

(BUR) Hidden text (added 07.07.14):
There is a hidden copyright text in ROM:
MUSIC_KA Version 1.1 in 1987-11-1Copywrite by Softhans ,Tomohiro Hori


Matsumoto Tooru no Kabushiki Hisshou Gaku 2

(GEN) Password screen (added 07.12.13):
Hold A + B + Select + Start on controller 1, then press Reset. A password screen, otherwise unavailable on the title screen, will appear.
Source: ReyVGM

Mechanized Attack

(UNI) Debug menu (added 14.01.12):
At the title screen, hold Down + Left + B + Select on controller 1, then press Right + A + B on controller 2. Then release all the buttons. Additionally, you can remove the clothes of the girl, used as the cursor menu. Initially, girls is fully dressed. Set "PLAYER", "MAGAZINE", "GRENADE" and "CONTINUE" options accordingly to values described below, to step by step undress the girl: 1776, 1815, 1266, 6666. If you enter finally 4444, then screen will change to just a single pentagram and locks.

Mega Man, Rockman

(BUR) GameGenie (added 07.07.14):
PEXPIIAA-Re-enables some strange easter egg. Hold A on controller 2 while falling from any obstacles to change the landing animation.

Mega Man 2, Rockman 2 - Dr. Wily no Nazo

(FIX) Easter egg:
At the Stage select screen, hold A and choose a boss. When the next screen comes up that displays the boss and his name, the stars in the background will turn into birds.

Mega Man 3, Rockman 3 - Dr. Wily no Saigo!

NTSC versions:

(FIX) Freeze animations:
Hold Up + A on controller 2 to freeze some of the animations, including the rockman's hit animation or explosions, also it does work on some bosses. This debug leftover was removed from the European version completely.

(FIX) High jump and no death pits (added 07.07.14):
Hold Right on controller 2 to jump two times higher and faster during the game. This also affects the falling into the pits, instead of instant death you will land on the solid floor under the screen and can jump out of there unharmed up to the top of the screen. This debug leftover was removed from the European version completely.

Mega Man 4, Rockman 4 - Aratanaru Yabou!!

(BUR) GameGenie (added 07.07.14):
PAEAPEGE-Re-enables the palette editor, similar to those from part 5, but since there is no more debug code left, we don't know where it should be called properly.

Mega Man 5, Rockman 5 - Blues no Wana!

(BUR) GameGenie (added 07.07.14):
ATUKGUOZ (for the US version and the Japanese version)
ATUKZUOZ (for the European version)
-Re-enables the debug features. On controller 2, press Left to pause/unpause the game, press Up to pass through obstacles, press Right to restore your energy and edit the palette (with controller 1, change the palette, press Select to exit the edit mode and have your energy restored), press B to disable detection collision for the player.
Source: GSHI

Mega Man 6, Rockman 6 - Shijou Saidai no Tatakai!!

(BUR) GameGenie (added 24.12.09):
EZKKIVKG+LLVKATOL+AXEGLVTU-Re-enables the debug menu. Press A to show the menu after reset. Use controller to view sprites data, change palette and listen all in-game music and sounds in sound test.
Source: GSHI

Meiji Ishin

(UNI) Strategy mode:
At the title screen, press Up, A, B, Left, A, A, A, A, B, Right, B, A, Down, B, B, A + B on controller 2, then press A on controller 1 up to 8 and press Start. If done right, the game will start right from the strategy events, at the level according to how many times A was pressed.

Meimon! Dai San Yakyuu Bu

(UNI) Secret passwords (added 07.12.13):
みたいみ たいおわ りみたい-View Ending Sequence

Meimon! Takonishi Ouendan - Kouha 6 Nin Shuu

(UNI) Sound test (added 04.10.07):
At the very first briefing screen after selecting the game mode (start new or continue), before the map screen appears, hold A + B + Select + Start.

(UNI) Invulnerability (added 11.09.08):
At the map screen, select and enter "パスワード" option where your current password is displaying, then press Up, Up, Down, Down, Left, Right, Left, Right, B, A. A sound will confirm correct code entry. Enter this code one more time to toggle this cheat off. Every time you enter it, it will toggle on and off again.

(UNI) Credits (added 13.09.08):
After the game completion, at the "完" screen, press Up, Up, Down, Down, Left, Right, Left, Right, B, A, B, A, A, B, A, B, Right, Left, Right, Left, Down, Down, Up, Up.

Meitantei Holmes - Kiri no London Satsujin Jiken

(GEN) Picture test:
At the title screen, press A 30 times then press Start.

(UNI) Sound test:
At the title screen, press A 20 times then press Start.

(BUR) Gamegenie (added 05.01.14):
TEVGPGGZ-In addition to two known cheats, the game contains more disabled debug options. Using this code you can re-enable three more:
At the title screen, press A 5 times, then press Start to enable the Scene test mode.
At the title screen, press A 2 times, then press Start to enable rather glitched game mode with unknown meaning.
At the title screen, press A 8 times, then press Start to enable not working Sequence test mode.

(BUR) Hidden text (added 23.11.08):
There is a hidden copyright text in ROM:
1987. Another Ltd.


Meitantei Holmes - M Kara no Chousenjou

(GEN) Secret passwords:
シーントバシ-Scene select
ビージーエムガキキタイ-Sound test
エガミタイ-Go anywhere
エンディングガミタイヨ-Ending
Source: ReyVGM

Melville's Flame

(BUR) Hidden text (added 10.07.14):
There is a hidden copyright and version string inside the ROM:
Copy right 1987 by Hiroyuki Shimamurarevision 871015.00 for 「メルビル ノ タタカイ」.
Additionally, the SRAM test routine in this game uses string:
RAM part test ID


Menace Beach

(UNI) Skip level (added 21.04.10):
There are two different ways to trigger this cheat. First one: at the title screen, press Left, Select, Left, Left, Left, Left, Left, Left, Up, Up, Up, Up, Up, Up, Right, Right, Right, Right, Right, Right. When you press correct button (except the first one), white color changes to red. A sound confirms correct code entry. Then press B to trigger cheat and message "YOU BIG CHEATERHEAD!" will appear. Second one: start a new game, then press Up on controller 2 and Up + A + B on controller 1 at the same time, you will be returned back to the title screen if all done right, then start a new game. When cheat is enabled, during the game press B + Select on controller 1 to advance to the next level, up to ending animation sequence.

(UNI) Secret message (added 21.04.10):
Complete the game. When the ending animation sequence is over and a message "PRESS A TO REPLAY SCREEN, PRESS START TO RESTART GAME" appears, hold Down + Left + Select. When you holding these buttons, a sound will play 10 times then 5 times in row and the secret message will appear at the bottom of the screen.

Mendel Palace, Quinty

(GEN) Bonus levels:
Hold Select + Start and press Reset.

(UNI) Two player mode (added 11.07.14):
At the stage select screen during the single player game mode, press Select + Start on controller 2 to enable the two player game mode.

(BUR) GameGenie:
ZAKLSGAA (for the US version)
ZASLEGAA (for the Japanese version)
-Debug menu. At the title screen, hold B and press A to toggle the ingame debug flag on and off, press Start to enter the debug menu with invulnerability and stage select.
AUKXYXXT+LESZAXXT (for the US version)
ALEZLUXT+LAEZGUXT (for the Japanese version)
-In addition to the code above re-enables in-game debug features. Hold B and press A at the title screen, Start to pause, Start to advance frames, Select to unpause, Down + Select to swap layers, Select + Start to reset.
Source: BMF54123

Metal Fighter, Mei Loi Siu Ji (Sachen / Kinema Music / Color Dreams), Wei Lai Xiao Zi (Joy Van)

All versions:

(UNI) Extra 16 lives (added 25.01.10):
At the title screen, press Down, A, Up, A, then press any other button, except A. Start a new game before demonstration begins.
Source: Yakovlev Victor

Joy Van / Color Dreams versions:

(GEN) Level select:
At the title screen, press Select a number of times one less than that of the desired starting level, then press Start. There is no such cheat in Joy Van version with the Chinese title and in Joy Van / Kinema Music version.

Metal Flame Psybuster, Metal Mech - Man & Machine

(UNI) Level skip (added 18.11.12):
During the game, in the mech mode, press Start to enter the game menu. Enable the "METAL FLAME" option, while credits is displaying on the screen, press Left + A + B + Select + Start.

Metal Max

(BUR) Hidden text (added 11.12.08):
There is some hidden text in the ROM:
Program: FX-702P


Metal Slader Glory

(UNI) Secret passwords:
でばっぐ やろう★-Debug Mode
えりな もう おきなよ-Skip the intro quest and jump directly to the Introduction credits.
Source: Pennywise

Metroid

(GEN) Secret passwords:
NARPAS SWORD0 000000 000000-Invincibility and Infinite Missiles

Mezase Pachi Pro - Pachio-kun

(FIX) Secret message (added 04.02.13):
Start a game of pachinko, and press Select to open the pause menu. Select the third option and press Select 12 times. Then select the second option and press Start 12 times. Finally select the first option and press A. A secret message will appear. This also enables the Air Lever hack cheat automatically.
Source: ReyVGM

(FIX) Fever time:
Start a game of pachinko. Press Select to open the pause menu. Select the third option and press Select 12 times. Then select the second option and press Start 7 times. Finally select the first option and press A. A message will appear. Once in the game again, press Up + A + Start to enable Fever Mode. Note that Fever Mode can be enabled at the different time in different pachinko machines. This also enables the Air Lever hack cheat automatically.
Source: ReyVGM

(UNI) Hack the air lever (added 15.07.14):
Start a game of pachinko, and press Select to open the pause menu. Select the third option and press Select 10 times. Then select the first option and press A. A sound will confirm correct code entry. A coin will appear near the air lever in the bottom-right corner of the screen. Now you don't need to press the A button to throw the balls. Additionally, this fixing the air lever, so it won't slide by itself over time.

(UNI) Increase luck (added 15.07.14):
Start a new game, at the intro animation, wait for the Pachi-kun starts riding on the bike. While on ride, quickly press Select 10 times. A sound at the end of the route will confirm correct code entry. From now, all pachinko machines will operate at the 99% of luck, instead of random one, generated at the game start.

(BUR) Hidden text (added 04.12.08):
There is some hidden text inside the ROM:
/ Computer designed by Marionette co. / Programmed by Marionette co. / Staff: O.Takayuki, S.Yoshiaki, O.Masataka, I.Masanobu, I.Taka /
and
ii debugger ga hoshiiyo/dareka YHP no debugger kattekure/ongaku ga dasaiyo/graphic ga dasaiyo/onaka suitayo/nenuiyo/hayaku kaeritaiyo


Mezase Top Pro - Green ni Kakeru Yume

(UNI) SRAM clear (added 15.07.14):
Hold A + B + Select + Start, then press Reset.

(UNI) Ending sequence (added 07.12.13):
Hold Down + B on controller 1 and A + B on controller 2 at the same time, then press Reset. You can view additional ending scenes if hold Select and/or Start on controller 1 (noting - ending 1, Start - ending 2, Select - ending 3, Select + Start - ending 4).

(UNI) Debug mode (added 07.12.13):
Hold Up + B + Select + Start on controller 1 and A + B on controller 2 at the same time, then press Reset. The Debug mode disclaimer will appear. If you want it to be enabled, just wait. If not, press Reset again. If enabled, during the game press Select to enter the palette edit mode. In map mode, press Start to immediately win the current round.

(BUR) Hidden text (added 15.07.14):
The SRAM initialization routine in this game uses the string
SAILOR VENUS M.A
as valid data header.

MiG 29 - Soviet Fighter

(FIX) Secret words:
Enter one of following words as player name for the hi-score table:
"PETE...."-Bonus Life
"TOBY...."-Bonus Weapons
"LINUS..."-Multi Bonus
"PREVIEW."-Level Five Preview
"GLIMPSE."-Last Level Glimpse

(UNI) Level select (added 15.07.14):
At the title screen, when the "PRESS START" message appears on the screen, press Up, Down, Left, Right, then hold one of the following combinations and press Start to start from corresponding level.
A-Mission 2
B-Mission 3
A + B-Mission 4

(UNI) Smiley test:
Absolutely all games by Codemasters have internal PRG ROM and CHR RAM testing routines. So called "Smiley tests". Tests are normally enabled, but for triggering it needs pressing all D-Pad buttons. Hold Up + Down + Left + Right + A + Select + Start to enter the PRG ROM test or hold Up + Down + Left + Right + B + Select + Start to enter the CHR RAM test, and press Reset. A green smile means that test passed, red sad face - failed.

Michael Andretti's World Grand Prix, Nakajima Satoru - F-1 Hero

Japanese version:

(UNI) Secret passwords (added 07.12.13):
さとる*MN-M represents the Level number with letters あいうえおらりるれ (levels from 1 to 9).
N represents the round number. Each level have it's own maximum number or rounds.
Level 1 - 4 rounds, level 2 - 5, 3 - 6, 4 - 7, 5 - 8, 6 - 10, 7 - 12, 8 - 14, 9 - 16. So you can enter any of letters あいうえおらりるれろかきくけこや representing the allowed numbers from 1 to 16 accordingly.
For Example, password "さとる*れろ" will lead you to level 9 round 10. Unfortunately, level 9, round 16 password crashes the game.

US version:

(UNI) Secret passwords (added 07.12.13):
SAMMY*IJ-I represents the Level number with letters from A to I (levels from 1 to 9).
J represents the round number. Each level have it's own maximum number or rounds.
Level 1 - 4 rounds, level 2 - 5, 3 - 6, 4 - 7, 5 - 8, 6 - 10, 7 - 12, 8 - 14, 9 - 16. So you can enter any of letters A to P representing the allowed numbers from 1 to 16 accordingly.
For Example, password "SAMMY*IJ" will lead you to level 9 round 10. Unfortunately, level 9, round 16 password crashes the game.

Mickey Mania, China Rabbit Baby

(UNI) Stage select:
Hold A + B + Select at the title screen.

(UNI) JY company's Easter egg:
Press Up, Up, Up, Up, Down, Down, Down, Down, Left, Left, Right, Right at the title screen.

Mickey Mouse, Mickey Mousecapade

(FIX) Continue (added 11.07.14):
At the game over screen, hold at least one D-Pad button on controller 1 and press Start.

(GEN) Level warp:
At the title screen, hold Select and one of the following buttons, then press Start:
Up-Castle stage
Right-Ocean stage
Down-Pirate stage
Left-Woods stage

(BUR) Hidden text (added 11.07.14):
The RESET routine in this game uses string
KIKU
to check if game was soft or hard reset.

Micro Machines

All versions:

(UNI) Smiley test:
Absolutely all games by Codemasters have internal PRG ROM and CHR RAM testing routines. So called "Smiley tests". Tests are normally enabled, but for triggering it needs pressing all D-Pad buttons. Hold Up + Down + Left + Right + A + Select + Start to enter the PRG ROM test or hold Up + Down + Left + Right + B + Select + Start to enter the CHR RAM test, and press Reset. A green smile means that test passed, red sad face - failed.

Aladdin version:

(FIX) Extra 6 lives with qualify and credits (added 15.07.14):
Complete the Qualify race, no matter if you fail or qualify. Before the end of the race, hold Up + B + Select on controller 1. Continue holding these buttons and when the screen changes color, press Start on controller 1. A secret credits screen will appear. Press Start to continue the game qualified to challange with extra 6 lives.

Regular version:

(UNI) Extra 6 lives with qualify and credits (added 15.07.14):
Fail the Qualify race (you must finish 3rd or 4th). Before the end of the race, hold Up + B + Select on controller 1 and Right + A + Select on controller 2 at the same time. Continue holding all these buttons and when the screen changes color, press Start on controller 1. A secret credits screen will appear. Press Start to continue the game qualified to challange with extra 6 lives.

Might and Magic

(UNI) SRAM clear (added 07.12.13):
Hold Down + A + B on controller 2, then press Reset. While screen is black, release Down and press Up, Right, Up, Left. The previous saved game will be erased.

(BUR) Disabled cheat (added 07.12.13):
During name entry, hold Down + B on controller 2, then press A on controller 1. The jump after the check opcode was NOPed, so it's unknown currently, where it goes to jump.

Mike Tyson's Punch-Out!!, Punch-Out!!

All versions:

(FIX) Secret passwords:
075-541-6113-"Busy signal".
800-422-2602-"Busy signal" of Nintendo's customer service phone number.
206-882-2040-"Busy signal".

English versions:

(FIX) Secret passwords:
135-792-4680-"Another World Circuit" access. To enable this password hold Select and press A + B when you entered it.
106-113-0120-"Credits". To enable this password hold Select and press A + B when you entered it.
007-373-5963-"Dream Fight" with Mike Tyson.

Millionaire (Sachen)

(UNI) Secret message (added 10.04.10):
During player one turn, press Up, Start, Left, Select, Down, Select, Right, Start, Select, Select, Start. The secret message will appear.

Mindseeker

(BUR) GameGenie (added 05.02.13):
GEVTZPEI-Some of the Namco games, which uses the 19 mapper PCB, contains also the specific self-test routine. It can test and initialize the internal RAM buffers. Similar to the other Namco games series, in order to run these tests, you must plug in a special device to the famicom expansion port. This device is much simpier than mentioned another device. It just takes one bit of data and immediately returns it inverted to the data port, there is no FIFOs inside. When the program detects the device presence, it performs RAM test and initialization. If RAM is already tested/initialized, the screen will turn blue. If RAM isn't initialized, but after init and test all is fine, then screen will turn yellow or pink. If, even after the reinitialization, RAM test fails, then screen will turn red. After the tests, program goes to the infinite loop, so yo must unplug special device to boot into the game. Using this Game Genie code you can skip the special device check and just directly to the RAM initialization routine. This game tests it's IRAM buffer, used for the expansion sound.

Minelvaton Saga

(UNI) Debug mode (added 02.01.09):
At the title screen, press Up, Up, Down, Left, A, Left, Right, Down, Down, B, press Start and the title screen will change color to black. During the game, press Start to enable and Select to disable debug mode, which includes the faster movement speed and disables random encounters.
Thanks to KeyBlade99 for corrections.

(UNI) SRAM clear (added 16.04.14):
Hold Up + Down + Left + Right on controller 2, then press Reset. Now, the program is waiting for A on controller 1 to be pressed. When you press it, if SRAM is properly initialized, a message オーケーです ("OK") will be displayed on the green background for a very short time, then game will continue. In other case, you'll see a message ダメ ラムエラー ("BAD RAM ERROR") on the red background. Press B and WRAM will initialize and message でんばんを オフしてください ("TURN THE POWER OFF") will appear, and background change it's color again.

Miracle Ropit's Adventure in 2100

(UNI) Continue (added 02.01.09):
After death on the level 2 and later, at the game over screen, press quickly A, A + B, Up + A + B, Down + A + B, B on any controller, you'll continue the game from the last played level with 3 lives.

Mirai Senshi - Lios

(UNI) Ending sequence (added 07.12.13):
Hold Up + A + Select on controller 1, then press Reset.

(UNI) Sound test (added 16.07.14):
Hold Up + B + Select on controller 1, then press Reset. Unfortunately, probably due to programmer's bug, if you exit from the Sound test with Start, you'll continue in rather broken highly glitched game.

(UNI) Instant continue (added 16.07.14):
Hold Down + A + Select on controller 1, then press Reset to jump directly to the saved previously game, skipping the title screen and intro.

Mirai Shinwa Jarvas

(UNI) Teleport to start (added 02.01.09):
During game, press Up, Up, Down, Down, A, B, A, B on controller 2 and you will be returned back to the starting point.

(UNI) SRAM clear (added 16.04.14):
Hold Up + Down + Left + Right on controller 2, then press Reset. Now, the program is waiting for A on controller 1 to be pressed. When you press it, if SRAM is properly initialized, a green message "OK!!" will be displayed on the for a very short time, then game will continue. In other case, you'll see a red message "NG!!". Press B and WRAM will initialize and message "PWR OFF" will appear.

Mission Impossible

All versions:

(UNI) Secret passwords (added 16.07.14):
LRHN-Level 1
KMVW-Level 2
XDGJ-Level 3
QBYZ-Level 4
HMPR-Level 5
TVJL-Level 6
YGKX-Computer level. To enable this password, hold Up + A + B on controller 2, then press A on controller 1. In other case, it won't be accepted.
MTKN-Computer password. Can be accepted only in the Computer level at the end of the game. This password will be given to you during the game.

(UNI) Invulnerability (added 16.07.14):
Select the continue option, enter password for Level 1 (LRHN), hold Left + A + B on controller 2, then press A on controller 1. You will start a new game invulnerable for a regular enemies attacks, but you still could be hit by the car, or be captured, etc.

(BUR) Hidden text (added 17.07.14):
There are a build dates of the ROMs in every version of this game:
MAST900417
-for the US version
MSTR910708
-for the European version
MSTR910718
-for the French version

European versions:

(UNI) Invulnerability (added 17.07.14):
Hold Up + Right + A + B on controller 2, then press Reset. This cheat added in the European version as a shortcut for the LRHN password cheat, but latter is still present in the game and can be used too. As against regular invulnerability cheat, you can use this one not only from the beginning, but from any level you could access with password, except the first one. If you enter the Level 1 password after enabling cheat this way, it will be disabled.

Mito Koumon - Sekai Manyuu Ki

(UNI) Quick password exit (added 17.07.14):
At the password screen, press A on controller 2 to immediately return to the title screen. This is a leftover from the developement stage of the game, other similar shortcuts was removed in the final version.

(BUR) GameGenie (added 17.07.14):
VTVUTVXT+ZPVUYVXV-Re-enables the map screen shortcut. Press A on controller 2 to skip directly to the next stage.
VTXSVXXT+ZPXSNXXV-Re-enables the in-game shortcut. Press A on controller 2 to complete current stage.

Mitsume ga Tooru

(UNI) Debug menu:
At the title screen, hold A + B on controller 2 and Select on controller 1 at the same time, then press Start.

(UNI) Level select (added 13.01.10):
At the title screen, hold A + B on controller 2, then press on controller 1 A, A, A, A, B, B, B, B, A, B, A, B, A, B, A, B.
Source: Yakovlev Victor

(UNI) Extra money (added 22.09.15):
At the stage number screen, on controller 1, hold Select, then press repeatedly two different D-Pad buttons one by one as fast as you can. For example, repeat Up, Down or Left, Right. Pause between pressings should be less than 1/8 second, but you could do it faster. If all is done right, every 8 button pressed the money counter will be increased by 1000 and you hear the sound. With this cheat you may obtain 2000-5000 at the beginning of every stage for free.

(BUR) GameGenie (added 22.09.15):
XTKGIZAV-Re-enables the debug ingame handler.
During the game, on controller 2 press:
A or B to increase money amount by 10 and 1000 correspondingly.
Left to toggle the CPU usage meter on/off.
Up to skip current level.
Right give all weapons, a bird and a powerful spear
Down to refill health bar.
ILVAGOOY+XAVAIPOA-Replaces the stage select cheat with the disabled one at the title screen. Hold A + B in controller 2, then press A, A, A, A, A, A, A, A. The color of the title screen letters will change to purple. Unfortunately, this is all what is left from appears to be a "Special mode" of this game. There is no code to use this cheat flag at all.

Mo Jie Ba Zhu (Nanjing, NJ079), Mo Jie Ta Shi (Nanjing)

(UNI) Secret message (added 21.05.14):
During the game, while in conversation mode, hold Up + Select + Start on controller 1 and skip with A to the end of the dialog. The copyrigh string will be displayed in the dialog box. This cheat can be found in a couple of Nanjing games on the same engine.

Moai-kun

(GEN) Stage select:
At the title screen, highlight Continue, then hold Down + Select, the cursor will return to the Start option, now press Start.
Source: ReyVGM

(BUR) Hidden text (added 17.07.14):
There is a hidden version info inside the ROM:
MAST891020


Mobile Suit Z Gundam - Hot Scramble

(UNI) Debug monitor (added 09.06.09):
At the title screen, on controller 2 press A, Up + A, A + B, Up + B, B, Right + B, A + B, Right + A, Right + A, Left + A, A + B, Down + A + B, Down + B, a message "MONITOR ON" appears instead of the hi-scores, but only if the title screen is renewed after the demo sequence. From now there is some debug features will be available. Instead of score string you can see one-byte memory viewer, while on pause you can change addresses by pressing Up or Down on controller 1 or buttons on controller 2, with Select on controller 1 you can advance game by frame by frame.

(BUR) Hidden text:
The RESET routine in this game uses string
by Kei Cross
to check if game was soft or hard reset.
Source: tcrf.net

Moero TwinBee - Cinnamon Hakase wo Sukue!, Stinger

Japanese version:

(FIX) Continue (added 07.12.13):
During 3 Players game, when any of ships is destroyed and "GAME OVER" is displayed, the player should hold button according to it's number: Player 1 - Up + A + B, Player 2 - Left + A + B, Player 3 - Right + A + B. Then player will instantly returned to the game. Do not allow to destroy more than one ships at once, this cheat only works if two other players are alive. The US version still has this cheat, but there is no 3 or 4 players game mode, so you couldn't do it.
Source: ReyVGM

Momotarou Densetsu

(UNI) Secret passwords (added 04.10.07):
すべてのきよくがききたいな-Sound test
すべてのてきがみたいな-Picture test

Momotarou Densetsu Gaiden

(GEN) Sound test and ending (added 29.10.15):
Complet all three scenarios of the game to unlock the hidden options "Sound Test" and "Ending" in addition to the Introduction menu option.
Source: KingMikeX

(UNI) Window Frame Design Room (added 07.12.13):
Hold Down both on controller 1 and controller 2, then press Reset.

Momotarou Dentetsu

(GEN) Secret words:
Enter first three names in the 3-player mode as in table below. Note: C1 player name is "モモタロ" by default, do not change it! Or else you couldn't enter it again:
C1:"モモタロ" C2:"おんがく" C3:"しつ"-Sound test
C1:"モモタロ" C2:"びじゅつ" C3:"しつ"-Picture test

Money Game, The

(UNI) Ending sequence (added 08.12.13):
At the title screen, hold Down + Left + A then press Start. While screen is black, press B, A, A, A, B, A, A, A, B, A, A, A, A, B, B, A, B, A, B, B, A, B, B, A, B.

(UNI) Stage advance skip (added 08.12.13):
During the game, press Select to enter to the Save Menu, select the second option, then hold Right + A + B on controller 2 and Right + B on controller 1 then press A on controller 1. From now, you can advance to the next stage without money counting.

(UNI) Competition mode (added 08.12.13):
During the game, press Select to enter to the Save Menu, select the second option, then hold Left + A on controller 2 and Left on controller 1 then press A on controller 1. Enter your ID and password and answer "Yes", the game will be switching to the competition mode.

(GEN) Extra 3 million yen:
First, go bankrupt. Then, on the game over screen, press A + B at the same time on both controllers. You'll go back to the title screen, start over and you'll have 3 Million Yen this time around.
Source: ReyVGM

Money Game 2 - Kabutochou no Kiseki, The

(UNI) Skip intro (added 18.07.14):
At the title screen, enter the "START" option, then select one of the game modes. Press A + B and keep it pressed before the game screen appears.

(UNI) Instant phone calls (added 18.07.14):
During the game, in some cases you couldn't make a phone calls. Hold A on controller 2 before call to avoid all restrictions.

(UNI) Market helpers (added 18.07.14):
During the game, click on the computer, select the second menu option (market trade), then hold A + B on controller 2 and press A on controller 1. An extra column will appear in the market list with some additional info to the prices.

(UNI) Instant Kohinata-san talk (added 18.07.14):
During the game, click on your notebook, select third option and then ask for talk with Kohinata-san (first menu option), sometimes you couldn't do it, because of late hours or he is gone. Hold A on controller 2 before entering first menu option to be able to speak with him any time.

(UNI) Kohinata-san talk (added 18.07.14):
During the game, go to speak with Kohinata-san as decribed above. Before talk, hold A on controller 2 to show the list of objects to select before talk.

(UNI) Kohinata-san talk (added 18.07.14):
During the game, go to speak with Kohinata-san as decribed above. Select the second option (persuasion), hold A on controller 2, then press A on controller 1 to always persuade.

(UNI) Extra 5 million yen (added 18.07.14):
At the game over screen (first game over), hold Up + A + B on controller 2 and press A on controller 1. The game will immediately start from the beginning with different intro sequence and you'll get 3 million yes at the beggining, instead of 2, as well as pretty secretary.

(UNI) Second chance (added 18.07.14):
At the game over screen (second game over), hold Up + A + B on controller 2 and press A + B + Select on controller 1. The game will return to the previously ended game with no money and day before the game over again.

Monster In My Pocket

(UNI) Skip copyrights:
When the copyright screen appears, hold A + B + Select and press Start to jump directly to the intro sequence.

(UNI) Sound test:
Right before the title screen appears, at the copyright screen hold Right + A + B and press Start. If you do not want to wait for copyrights screen disappear hold additionally Select.

(BUR) GameGenie (added 15.01.08):
GEKLXKGK (for the US version) GEKLOKGK (for the European version)-Re-enables the level select cheat. At the player number select menu, press Right, Left, Down, Up, A, B. A sound will confirm correct code entry. Then press Start. Note, the level 6-3 is inaccessible.

(BUR) Hidden text (added 19.07.14):
There is a hidden version text inside the ROM:
MAST911001


Monster Party

(GEN) Secret passwords:
055*N-Level select passwords. Just put any number from 0 to 7 at N place. Note, "*" denotes a skull.

Monster Truck Rally

(BUR) Hidden text (added 08.12.13):
At the very end of the ROM a simple copyright scring exist:
 by Rick Koenig 


Moon Crystal

(UNI) Stage select (added 01.01.08):
Hold Up on controller 2, then press Reset.

(UNI) Debug leftovers (added 19.07.14):
The Maclonna Mines stage boss have a leftover from the developement stage. Press A on B or Down on controller 2 to force the boss throw the rock for corresponding range any time. This is most probably was used for debugging throwing animation and wasn't removed from the final version.

Moon Ranger

(UNI) Unlimited continue (added 08.12.13):
Normally, after the game over screen you need to press A + Start to continue the game, but if you additionally hold Down, continue counter won't decreased, you can continue with pressed Down as much as you want.

(UNI) Invulnerability and Level skip (added 08.12.13):
After the game start, hold Up on both controllers, then press A + B on controller 1. Now some cheats are enabled, hold A and press Select to enable invulnerability. Return back to the game by pressing Select one more time. Or hold B then press Select to skip the current level.

Morita Kazuo no Shougi

(UNI) Start round from the beginning (added 21.07.14):
Normally, the game will track all played moves from both players and can restore the last played game after the reset or power off. If you hold B on any controller at the title screen, before the game start, the game will rewind to the very first move of this round, and you can track all the moves from the beginning using the replay mode, or start to play from any move. This is actually can be done with the replay mode itself, but with this cheat, you just jump to the beginning of the reound.

(UNI) Reset last played game (added 21.07.14):
At the title screen, hold Up + A + B, then press Start on controller 1. The last played game will be erased.

(BUR) Hidden text (added 21.07.14):
There are a hidden copyright and version strings inside the ROM:
MORITA SHOUGI (C)1987  RANDOM HOUSE
MORITA SHOUGI Ver 1.0


Mortal Kombat II/III Special (JY)

(UNI) JY company's Easter egg:
After the demonstration start, at the player select screen, press Up, Right, A, Down, Right, B, Up, Left.

Mortal Kombat V (YOKO)

(UNI) 2-Player mode (added 21.07.14):
During the 1-Player game, press A + B on controller 2 to switch the game to the 2-Player mode instantly and return back to the play selection menu.

Motocross Champion

(UNI) Secret passwords (added 21.07.14):
あまのんははら-Ending sequence
いいたんたこす-Game over sequence

Mottomo Abunai Deka

(BUR) GameGenie (added 08.12.13):
GEXKZKNY-Re-enables the Level Select cheat and invincibility. At the title screen, press any button and then Start to start a new game. After selecting number of players and introduction, a Level select screen will appear. Press A or B to change the Level number, press Start to start with it. Invincibility is enabled by default.
Actually, there was a cheat sequence at the title screen, P, Up, Down, A, A, B, Left, Right, A, test for it was removed from the final version of the game. The different cheat modes was intended to be enabled when you succesfully press at least 2 or 4 buttons in sequence. So, level select is enabled when you press 2 or 4 buttons, invincibility is enabled with you press at least 3 or 4 buttons. Total sequence is 8 buttons long, but thre is no more code that need so much buttons to press.

Mouryou Senki Madara

(UNI) Sound test:
At the title screen, press Down, Down, Up, Up, Right, Left, Right, Left, A, B.

Ms. Pac-Man (Namco)

(BUR) GameGenie:
EEOGAAAA-Re-enable the debugging features. At the title screen, press A + Select to enter the debug menu, use Left or Right to change the level. Press Select + Start to soft reset. Press A or B, to adjust level brightness.

(BUR) Hidden text (added 02.01.09):
The RESET routine in this game uses string
NAOKI HIGASHIO
to check if game was soft or hard reset. Naoki Higashio was programmer of "New Production" company developed this game. Also there is a hidden copyrigh message inside the ROM:
COPY RIGHT 19841993 NAMCO LTD.ALL RIGHTS RESERVED


Ms. Pac-Man (Tengen)

(GEN) Soft reset:
Press A + B + Select + Start during the game play to return to the game menu. Press A + B + Select + Start again to return to the title screen.

(UNI) Level skip:
Pause the game and press A, A, A, B, B, B, Up, Down, Left, Right, A, B, A, B, A, B, Up, Down, Left, Right, B, A, B, A, A, A, Up, Down, Left, Right. Now you can press Select to skip current level.

Muppet Adventure - Chaos at the Carnival

(BUR) Hidden text (added 08.12.13):
At the end of the NMI routine a string
nmitestmessage
exists.

Musashi no Bouken

(UNI) Sound test:
At the title screen, after message "push start" appears, press A, B, A, B, A, B, Right, Select. A sound will confirm correct code entry.

(UNI) Maximum level:
At the title screen, after message "push start" appears, press Select, B, A, Left, Right, B, Right, Select. A sound will confirm correct code entry.

Musashi no Ken - Tadaima Shugyou Chuu

(UNI) Slowdown the dog (added 25.06.08):
At the title screen, press Down + A + B on controller 1. A running through the screen dog will stuck, confirming correct code entry. From now the dog in game will be slower.

(BUR) Hidden text (added 19.03.17):
The sound engine has a small version string at the beginning of the code:
V5.01 V6.11


Mutant Virus, The

(UNI) Another quest (added 26.06.08):
At the title screen, hold Up + A + B + Select on controller 1, then press Start. An image of man in space suit changed as well as starting level.

My Life My Love - Boku no Yume - Watashi no Negai

(BUR) Hidden text (added 08.12.13):
At the end of the ROM a hidden copyright and version string:
Sirius Works 0051991.03.20


 

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