Debug Menu

The debug menu is where the magic happens! If it weren't for this (and the tile viewer, I suppose), we wouldn't have access to most of the unused rubbish hidden inside the games. A common question regarding this is...

What do I need to access the debug menu?

To access any of these debug options in Metal Slug 2 through 5, you will need a Neo Geo Debug BIOS.

On the real Neo Geo hardware, this entails replacing the BIOS chip with a modified one, which requires a soldering iron and the possible risk of futzing up your console, so tread carefully. Search sites like Console Passion if that's what you fancy.

For emulators, the BIOS is a .zip file. You'll already need the "neogeo.zip" BIOS to run games in the first place, but the "debugbios.zip" BIOS is required to properly access these features. The two should be placed in the same folder (preferrably the "/roms" folder), and should not be unzipped.
However, some emulators have a hard time recognising the debug BIOS. If so, try using the Universe BIOS (or "unibios")... and if that doesn't work, just throw every single BIOS file you can find into "neogeo.zip". That usually gets the job done.

With the debug BIOS installed, you should be ready to go.


All being well, the debug menu should appear!

The debug menu is mostly identical throughout all the Neo Geo games, and can be summoned at any time, so long as you can pause. Options are selected by pressing the A Button, and the B Button cancels. Pressing B or Select on the main debug menu will unpause and return to gameplay.


Accessing Metal Slug 6's debug menu

Big thanks to candy76041820 for bringing this to my attention and documenting most of it, and _MetalliC_ of the Emu-Russia forums for apparently discovering this!

Since Metal Slug 6 runs on Atomiswave hardware (it's unknown if the debug menu is present in the PS2 port), activating the debug menu is a little different:


If the game pauses, you've done it! Press again for the debug menu! If not, reset and go through the hooplah again. It may take a few tries.
The debug menu behaves identically to the Neo Geo menu, except it is navigated with Player 2's controls: use the Stick to move through options, A Button to select, and B Button to cancel or exit the menu.


Accessing Metal Slug 7's debug menu

A massive thank you to 이지우 (Lee Jiwoo) for unearthing the debug menu and providing all the codes to access it!
To enable the debug menu, you can either use the following Action Replay codes below, or use Cheat Engine to find the code address in DeSmuME and set its value to "1" (this has only been tested with DeSmuME v0.9.11).

Version Action Replay Cheat Engine
Japan: 2223FEA8 00000001 1456510F8
Korea: 22250428 00000001 145661678
USA: 0223F548 00000001 145650798
Europe: 0223F5A8 00000001 1456507F8


To open the debug menu, hold the Select Button and press the Start Button. If the game pauses and the word "PAUSE" appears, you're in! Do that again to open the menu. Press the A Button to select and the B Button to cancel. To close the menu, hold Select and press Start again.


Accessing Metal Slug XX's debug menu

Once again, hats off to 이지우 (Lee Jiwoo) for providing the access code for this!
Create a text file named "NPJH50044.ini" and enter the following code into it; make sure the code is for the appropriate regional version. This file can be read by the PPSSPP emulator or the CWCheat app on PSP hardware:

_C1 Debug (Japan)
_L 0x00558a40 0x00000001

_C1 Debug (USA)
_L 0x00554930 0x00000001


Hold the Select Button and press the Start Button to pause the game, and again to open the debug menu. Press Circle to select and X to cancel.


Other debug menus?

Although most of the Metal Slug games have debug menus, some have either not yet been found or function differently than the norm.

Debug Menu

Metal Slug 2/X
Metal Slug 3/4/5
Metal Slug 6
Metal Slug 7/XX

The debug menu is in a mixture of Japanese and English, and can be a bit hard to follow. Click an option to hop to its translation and explanation!


メニューを とじる(PAUSEしたまま)
MENU CLOSE (PAUSE STEP)

In Metal Slug 2 and X, this simply closes the debug menu and returns to the pause state.
From Metal Slug 3 onwards, it freezes the screen and steps forward one frame. The function can be repeated to step forward frame by frame, which is a great tool for screenshots. Simply open the menu and close it again to resume gameplay.


SET DEBUG DIP


Opens a sub-menu for toggling dipswitches. This allows you to tinker with a variety of features, including collision data, coordinate trackers, invincibility, and even the ability to destroy all objects with the press of a button! Metal Slug 6 and 7 feature so many they're spread across three windows. See Dipswitches for more info.


ステージ スレクト
STAGE SELECT


Opens a sub-menu for accessing any of the game's stages and screens. See the Missing Areas page for each game to see where each option takes you.


TEST STAGE


Opens a sub-menu for accessing test stages, areas designed to play around and experiment with the game's features, though often not very exciting. See the Missing Areas page for each game for more info.


サウンド テスト
SOUND TEST

Opens a new screen for playing and testing the game's music, sound effects, and sound channels. See Sound Test for more info.


COLOR BAR

Metal Slug 2/X only


Opens a new screen with red, green, blue and white colour gradients, for testing the monitor's colour settings. Open the debug menu and use the Stage Select to exit it.


ADXちょうせい
ADX Tuning

Metal Slug 6/7 only


A small menu for adjusting the sound. よみこみ セクタ サイズ / Reading Sector Size is for... well, I'll take candy76041820's word for it and assume it "adjusts the machine's inner read buffer". BGM ボリューム / Music Volume makes the music louder or quieter; 000 is the loudest, 512 puts it on mute, though the difference is negligible in Metal Slug 7.


スクロール カウンター セレクト
Scroll Counter Select

Metal Slug 7 only


A sub-menu used to start a screen a certain distance in, using the VIEW INFOMATION's "SCROLL" coordinate. The distance can be adjusted by pressing Left and Right; warping will reload the screen and may cause certain objects to not load. The player will enter the way they normally enter the screen, be it via parachute, walking in or falling in.


リセット
RESET

Metal Slug 3 onwards

And finally, selecting this will reset the game. In Metal Slug 7 it will instantly game over.

Dipswitches

Metal Slug 2/X
Metal Slug 3/4/5
Metal Slug 7/XX

The SET DEBUG DIP menu may not be interesting, but it's most certainly useful. It has a number of conveniences to make things easier than tinkering about with the games, such as invincibility and unlimited ammo, but some options can give you a glimpse into the workings of each game, seeing how the collision and hitboxes work for each object.

From Metal Slug 6 onwards, the dipswitches are categorised into ディップ1 / DIP 1 (player options), ディップ2 / DIP 2 2 (system coordinates and hitboxes), and ディップ3 / DIP 3 (audio and display options).

Some options may only function after a new area is loaded.
In the Neo Geo games, the dipswitches can also be activated through the "debug dipswitches" option in Kawaks.


ムテキ
INVINCIBILITY


Renders the player invulnerable to all damage, except instant death states such as crushing or falling down pits. Curiously, the Slug Flyer is still capable of losing its vulcan cannon after 3 attacks; thanks to candy76041820 for this little known fact!


VIEW INFOMATION


(Is there an "R" in the house?)
Prints a string of numbers along the top of the screen, for a variety of debugging purposes. From left to right, top to bottom:


Metal Slug 6 rearranges the information slightly: enemies are tracked along the EC line (and EB too, I think?), and it now tracks player 1's position with the P1 coordinates... but not player 2, strangely.


Metal Slug 7 adds additional information relating to the Nintendo DS' VRAM limitations. Heck if I can make heads or tails of it!


イツデモPAUSE
PAUSE WHENEVER


Removes the restriction from pausing on certain screens, such as endings.


VIEW GEO SCROLL A
VIEW GEO SCROLL B


Marks all land that the player can stand on with yellow shaded lines. This will result in visual glitches though, such as wonky scrolling, backgrounds objects or the HUD becoming invisible, and so on. If one dipswitch no longer works, try the other one - VIEW GEO SCROLL A stops working halfway through Mission 1 of Metal Slug X, for instance, but GEO SCROLL B will work for the remainder of the level.


Metal Slug 6 and 7 behave a little more reliably. VIEW GEO SCROLL A denotes static "backdrop" collision with deep-pink/purple lines, while VIEW GEO SCROLL B displays collision with sprite-based platforms using light-pink lines.


VIEW ATTACK RECT


Displays "attack" hitboxes with diagonal arrows; this shows what objects will damage things, be it the player or the enemy. Also used to show the range the player or enemy needs to be before they'll use their melee attacks.


Metal Slug 6 onwards differentiates the two; red rectangles dictate harmful objects, while white rectangles show the range when players and enemies will perform melee attacks.


VIEW BODY RECT


Displays "body" hitboxes with right-angles; this shows what objects react to damage, such as the player, enemies, destructible scenery, and hotspots.

Metal Slug 6 appears to colour-code objects: yellow rectangles can be walked through (enemy soldiers, etc) while blue rectangles are solid (shields, boxes, etc). Metal Slug XX adds on this by making the player's hitbox cyan, but Metal Slug 7 drops the colour-coding and all hitboxes are blue.


VIEW PUSH RECT

Metal Slug 3 onwards


Displays "push" hitboxes with triangles; this shows what sprites the player cannot move through, such as tanks, zombies and giant crabs.


Metal Slug 6 and 7 use green tectangles to denote these hitboxes. 7 also flashes this strange 3x3 teal square grid whenever the player uses a melee attack.


VIEW SCRNOUT RECT

Metal Slug 7 onward


Displays "interaction" hitboxes. Yellow rectangles are for hostiles (when a soldier will stop to knife you, etc.), pink rectangles are for passive objects (prisoners or interactive scenery), while pink lines stretch from objects to the player to determine pathfinding for wandering prisoners, whether the target is in range for projectile-shooting enemies, and more.


ムセイゲン グレネード
unlimited grenades


Grants the player unlimited grenades.


ムセイゲン POWガン
unlimited ammunition


Grants the player unlimited ammunition.


VIEW PAポイント
view player arrival point

Metal Slug X / Metal Slug 3

Marks on screen where the player will respawn if they die. Metal Slug 2 and X denote the position with a discoloured sprite of Satiko Suzuki, the grieving girl from the ending of the first Metal Slug, while the other Neo Geo instalments use a frame from Marco's respawn animation.

Metal Slug 6 / Metal Slug 7

The later games just use coloured lines; a white horizontal line in Metal Slug 6, and vertical blue and red lines in Metal Slug 7.


Dボタン、テキ ゼンメツ
D Button: enemy destruction


Ooh, baby! Press the D Button (or the L Button in Metal Slug 7/XX) to destroy everything on-screen. This includes killing enemies, freeing prisoners, wrecking scenery, and hitting hotspots.



"PAUSE"ヒョウジOFF
"PAUSE" INDICATOR OFF

Metal Slug 3 onwards

Removes the flashing "PAUSE" caption when paused.
BGM OFF

Metal Slug 3 onwards

Turns off the background music once a new screen is loaded... at least, in Metal Slug 3 it does! It doesn't appear to work in Metal Slug 4 or 5.

WARN パレット オーバー
WARN PALETTE OVER

Metal Slug 3/4/5 only

Beats the hell out of me! Any clues, readers?
ムセイゲン TIME
Unlimited Time

Metal Slug 6 onwards

Freezes the stage timer.
ムセイゲン ラッシュ ブラスター
Unlimited Rush Blaster

Metal Slug 6 onwards

The gauge for the coin-drop score bonus will never deplete.
レンシャ
Rapid Fire

Metal Slug 6 onwards

Holding the A button will fire your weapon continuously.
1INTモード
1INT [?] Mode

Metal Slug 6 onwards

Doubles the game speed.
TIME 00

Metal Slug 6 onwards

Reduces the timer to zero, killing the players instantly. Will continue to do so until disabled.
プレイヤー キョウセイ DEATH
Forced Player DEATH

Metal Slug 7 onwards

Instantly kills the player.
VIEW FRAME RATE

Metal Slug 7 onward

Displays a frame rate tracker at the bottom center of the screen, measuring when the game enters slowdown. "02" seems to be the norm, "03" is slight slowdown, and "04" or higher is when things get chuggy.
VIEW KEY

Metal Slug 7 onwards

Displays coordinates tracking button presses on the bottom-right; the top-left is player 1's controls.
The fourth digit tracks the D-Pad (Right is 1, Left is 2, Up is 4, Down is 8).
The third digit tracks the buttons (Fire is 1, Jump is 2, Grenade is 4 and Special Attack is 8).
The second digit tracks the Change Weapon Button (8).
The bottom-right coordinate changes as you progress through stages but I can't identify what changes it.
ザンコク ヒョウジ
Display Brutality

Metal Slug 6 onwards

Changes blood colour. If set to "ON", it is red; if "OFF", blood will be white. In the Neo Geo games, this is accessed through the Neo Geo BIOS dipswitches.
DIFF LEVEL

Metal Slug 6 onwards

Changes the difficulty level from 1 to 8; in Metal Slug 7, Easy is 1, Normal is 4 and Hard is 8. In the Neo Geo games, this is accessed through the Neo Geo BIOS dipswitches.
ガメンサイズ ベンコウ モード
Shrunk Screen Mode

Metal Slug 6 onwards

Zooms out the screen. This offers a wider field of view, showing when objects and enemies load in from off-screen, and offers pixel-accurate visuals in Metal Slug 6.
タテガメン プレイ モード
Tall Screen (Tate) Mode

Metal Slug 6 onwards

Rotates the screen 90 degrees counter-clockwise.
サュウ ハンテン プレイ モード
Mirror Mode

Metal Slug 6 onwards

Flips the screen horizontally (but not the HUD). Directional controls are flipped as well.
バイリニアフイルター
Vertical Filter

Metal Slug 6 only

?
バーチカルフイルター
Bilinear Filter

Metal Slug 6 only

Applies a blurring filter to all sprites.
スーパーサンプルフィルター
Super Sampling Filter

Metal Slug 6 only

Applies a blurring filter to all sprites.
ディザ OFF
Dithering OFF

Metal Slug 6 only

Disables dithering; only ever noticeable if you zoom in on sprites.
4:3モード
4:3 Mode

Metal Slug 7 onwards

Squashes the screen to 256x180.
ブラー モード
Blur Mode

Metal Slug 7 onwards

Applies a motion blur to the screen. The debug menu is prone to "burning in" until the background moves, as seen in the image above. Likely built in advance for the display options in Metal Slug XX.
サイダイキド
Maximum Brightness

Metal Slug 6 onwards

Adjusts the brightness to sprite-accurate levels. Enabled by default in Metal Slug 7 and XX.
カゲ ヒョウジOFF
Shadow Display OFF

Metal Slug 6 onwards

Disables all shadows if set to "ON". Enabled by default in Metal Slug 7 and XX; the shadows were only ever used in Metal Slug 6.
オブジェクト ヒョウジOFF
Object Display OFF

Metal Slug 7 onwards

Hides all sprite objects.
ハイクイヒョウジOFF
Background Graphics OFF

Metal Slug 6 onwards

Hides all background graphics.
FIXヒョウジOFF
Fixed Graphics OFF

Metal Slug 6 onwards

Hides all HUD graphics. In Metal Slug 6 the debug menu is still visible, but all other games hide it too!
トウバイヒョウジ
True Scale Graphics

Metal Slug 7 onwards

Zooms in the screen; this shows the sprites at their pixel-accurate size. The camera becomes more fidgety, and whips around when you turn left or right akin to Metal Slug Advance.
アンチエイリアス
Anti-Alias

Metal Slug 7 onwards

I'd assume this would enable anti-alias image softening, but I can't tell the difference!

Sound Test

Tucked away in the debug menu's fifth option is the sound test! There's a different interface between Metal Slug, 2 and X versus Metal Slug 3 onwards, but the basic function remains the same - the ability to test all the sound effects, voice clips and music tracks in the game.

In the first Metal Slug, this is accessed by ticking debug dipswitch 2-1, then while in a mission, holding Up and pressing the D Button. Thanks to Keitaro Red for this information!


Metal Slug / Metal Slug 2
The first three Metal Slugs utilise the same sound test screen, which helpfully explains all the controls at the bottom... albeit in a terribly vague manner.
1P UP/DOWN Scrolls through sounds forward or backward by 1.
1P RIGHT/LEFT Scrolls through sounds forward or backward by 10.
1P A BUTTON Scrolls down through the chanells.
1P B BUTTON Toggles between banks on the current channel, from 0000, 1000, to 1100.
1P C BUTTON Silences music.
1P D BUTTON Silences sound effects.
 
2P UP/DOWN Scroll up or down through the channels.
2P RIGHT/LEFT Scrolls through sounds forward or backward by 1.
2P A BUTTON Plays selection on channel 0.
2P B BUTTON Plays selection on channel 1.
2P C BUTTON Plays selection on channel 2.
2P D BUTTON Plays selection on channel 3.

Sounds are organised hexidecimally, from 20 to FF. You're best using player 2's controls, as player 1's are pretty fiddly and not very intuitive. The selections between all the channels are identical. 0020 to 0031 is used for background music. The 1000s are for gameplay sound effects - explosions, enemy screams, weapon sounds, background noises, and so forth. 1120 to 116E is mostly dedicated to voice clips - player screams, Allen O'Neill's taunts, and announcer chatter, with only a few exceptions.
Metal Slug X features a few voice clips that would go unheard until Metal Slug 3, such as the CEO's "hi!", Uki's chittering, and announcements for the Mobile Satellite and Thunder Cloud.


Metal Slug 3 and onwards greatly simplifies the sound test. There's no need to manhandle buttons on both players' sides, there's no mucking about between banks and channels. It's pretty straight forward, actually.
1P UP/DOWN Scrolls through sounds and options.
1P RIGHT Selects an option. Press again to exit option.
1P LEFT Scrolls between sound, bank, and function during a selection.
A/B/C/D BUTTON Plays corresponding option.

The sound test is a lot more customisable now. Each of the eight options can be fiddled with and played with the A, B, C or D Buttons on player 1 or 2's side. Besides selecting sounds and banks on each option, you can also change the function of that selection! The functions include...

Changing the function means you can turn individual buttons into fade outs, tempo modifiers, or silencers as you please. Not a lot to help to anyone but the developers and amateur DJs, but the user-friendliness is commendable.
This sound test remains in Metal Slug 4 and 5, though with spotty functionality. None of the music will play in 5's version, possibly due to its advanced sound quality rendering it incompatible.


Metal Slug 6 changes things up yet again and simplifies its to just playing sounds and music - forget about fade-outs and tempo-settings! On the bright side, you can now use the sound test without ending your gameplay session.
The first four settings will play sound effects, only starting at various category changes. 01 to 23 are mostly announcer voice clips, 24 to 30 are mostly sounds for the HUD, and so on.
The final option will change the background music.

As mentioned above, Metal Slug X features sounds not heard until 3, and it's quite possible there's more unused sounds to be found hidden deep inside them... but I'm deaf as a post and, jeez, do you know how many sound effects are in each individual game? It's a heck of a lot, pal. I'm in no place to distinguish one explosion from another and see if they're unused.
.... that said, if you can find anything worthwhile, good goin'!

Metal Slug dipswitches

The original Metal Slug has no debug menu (to anyone's knowledge, at least!), but it still retains functions that can be accessed via the debug dipswitches. You can find these in Kawaks under the Game > Neo Geo settings. On real hardware? Beats me, buddy!
Should anyone know any further functions to be found via the dipswitches, do let me know!

DIP 2-1


Displays seven sets of coordinates, six on the top-right and one beneath player 1's HUD.

This also enables access to the sound test and level select by holding Up and pressing the D Button. Thanks to Keitaro Red for this information!


Pressing the A and D Buttons simultaneously will behave like a primitive version of the VIEW GEO SCROLL dipswitch, highlighting terrain with hexadecimal tiles. This can also be done with the B and D Buttons too, using a different numbers and colours for the tiles; it is currently unknown what the difference is. Pressing the C and D Buttons will turn it off.


DIP 2-4


This switch will render the player invincible, and will lock the Metal Slug's health gauge at maximum. This also has the amusing side effect of making the player bounce off the electricity pylons in Mission 2.


DIP 2-5


This dipswitch specialises in tank tread physics, displaying coordinates and graphical indicators applying to the Metal Slug and the Girida-O tanks. The coordinates will not appear until a Metal Slug is on-screen, and will cease operations once it leaves the screen or is destroyed.
The purpose of the top set of coordinates are unknown. The middle set track the Slug's horizontal position on-screen, and the bottom set for the vertical position.

A set of unused graphics, balls with roman numerals, are used to record the position of the tank treads.

While on solid ground, all three balls are yellow. That means they're glued to the ground, and are active.


While jumping, the centre ball turns yellow and the others turn black. Only the yellow ball will pay attention to collision data of the ground.


Upon landing or crossing a slope, the side balls may turn white, meaning the tank may tilt in that direction until it stabalises on solid ground.


Likewise, if the Metal Slug tilts upon going up a slope, the tank itself will turn pale. It returns to normal colour upon rolling onto flat or 45-degree slopes. This, assumedly, is an indicator for what angle it will be facing when jumping.


DIP 2-6


Disables jumping. Yeah, uh, if you try to jump, you just stay rooted to the ground. Real handy. Anyone know what purpose this serves?

Metal Slug Advance
debug remnants

As of this writing, there's no known accessible debug menu in the game, but there are certainly several pieces of evidence towards one existing at some point. All hex coordinates relate to the Japanese version of the game, though each version is so similar there might not be much difference.
이지우 (Lee Jiwoo) unearthed the "VIEW INFOMATION" display, but the rest of the menu has yet to be found. You can access it using this savestate (compatible with VisualBoyAdvance-1.8.0-511).

ムテキ
ムセイゲン POWガン
ムセイゲン グレネード
Rボタン、テキ ゼンメツ
VIEW INFOMATION
VIEW ATTACK RECT
VIEW BODY RECT
VIEW PUSH RECT
VIEW GEO SCROLL A
VIEW GEO SCROLL B
"PAUSE" ヒョウジOFF
ON
OFF

At hex coordinates 00079AF0 exists some pretty clear debug dipswitches, which are carried darn near exactly from the Neo Geo games. The R Button is assigned to total enemy destruction, but all the winners are there.

USA
EUROPE
JAPAN
ENDING
select country
<< >>

Just above it at 000797B0, right behind the "PRESS START" text, is an unused country select option... which is interesting, since the Japanese version has complete English text for all menus and cards in its data.

Head
enemys:[ ]
morden:[ ]
_time_:[ / ]
player:[ / ]
level_:[ ]
_prio_:[ ]

At 00079270 lies these strange English phrases, that are actually leftovers of the VIEW INFOMATION debugger (see savesate).
Both ENEMYS and MORDEN record how many enemies have been defeated, though ENEMYS will record all enemies (tanks, helicopters, etc) and resets after a mission is complete. MORDEN only counts infantry and keeps a permanent record, likely to determine the unlock condition for the Soldier A, Soldier B, etc. cards.
TIME is simply a timer that counts up from the start of every screen. Likely used to determine the unlock conditions for the bosses' cards.
PLAYER is the player's health bar.
LEVEL and _PRIO_'s purposes are currently unknown.

The game has missing areas, and there's a full level select list (found by stoffhime1).

If you're talented enough to dig up this debug menu, tell me all about it!


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