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 all 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.
- Load up any Neo Geo Metal Slug game (except for the first) in console/AES mode.
- Now turn "Developer Mode" on (in Kawaks, at least - I don't know the procedure for other emulators or the real hardware). You may need to reset once it is turned on for the game to properly activate it; or you can disable the "Auto Run Game" option and tick it then, saving yourself the hassle of resetting.
- Make your way to the character select screen, and press the Select button twice (on emulators, the Select button should be the same as the Coin button).
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.
This page currently only reflects on the Neo Geo games (and 6). Regarding the other games:
- The first Metal Slug does not appear to have a debug menu, but does have debug dipswitches.
- Metal Slug 6 requires a different method of accessing its debug menu, but is otherwise much the same.
- Metal Slug Advance has textual remnants of a debug menu, but as of this writing it cannot be accessed, if it's still operational.
- As for Metal Slug 7, XX and the Neo Geo Pocket titles, it is unknown if they still possess debug menus.
Metal Slug 3 debug menu
The debug menu is in a mixture of Japanese and English, and a bit hard to follow, so translations and explanations will follow!
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.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! See below for more info.
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.
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.
Opens a new screen for playing and testing the game's music, sound effects, and sound channels. See below for more info.
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.
Metal Slug 3 onwards
And finally, selecting this will reset the game.
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.
Some options may only function after a new area is loaded.
The dipswitches can also be activated through the "debug dipswitches" option in an emulator.
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!
(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:
- PROCESS: Flickers hexidecimal numbers as actions take place on-screen. How much processing power is being used, I assume.
- FREE: Appears to be related to PROCESS. How much free processing power is left, I assume.
- ZOMBIE: Has no bearing on the zombie transformation from Metal Slug 3; this showed up before it, anyway! This seems to keep track of all 'dead matter' on-screen, such as flying soldier bodies, debris, etc.
- VIEW: The two figures track the horizontal and vertical positioning of the screen on the level's map.
- SCROLL: Shows how far into the level you've travelled.
- ENEMY: Records all enemies on-screen across nine two-digit coordinates. Seems to only record enemies vital to the screen's progression - incidental or endlessly spawning enemies usually aren't tracked on it.
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.
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.
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 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.
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.
Grants the player unlimited grenades.
Grants the player unlimited ammunition.
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 subsequent games use a frame from Marco's respawn animation.
D Button: enemy destruction
Ooh, baby! Press the D Button to destroy everything on-screen. This includes killing enemies, freeing prisoners, wrecking scenery, and hitting hotspots.
"PAUSE" INDICATOR OFF
Metal Slug 3 onwards
before / after!
Removes the flashing "PAUSE" caption from the screen.
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 onwards
Beats the hell out of me! Any clues, readers?
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...
- BGM SET: Plays music.
- S.E SET: Plays sound effects.
- S.E SET: Will interrupt a sound if it and S.E SET are set to the same value.
- FADE OUT: Currently playing music will fade out; fade is quicker depending how high it's set, from 00 to FF.
- FADE IN: [I can't get this option to work for me!]
- TEMPO: Alters the tempo of music, from ungodly slow (0000) to double speed (FFFF).
- BGM STOP: Silences music.
- S.E STOP: Silences sound effects.
- ALL STOP: Silences everything.
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!
Displays seven sets of coordinates, six on the top-right and one beneath player 1's HUD.
- The set beneath the HUD denotes on-screen enemies, though it doesn't seem to recognise some foes, particularly endlessly-spawning enemies.
- The small green marker is where the player will respawn.
- The coordinates on the left-side tracks how much of the level has been travelled.
- The centre-top and centre-middle sets record horizontal screen coordinates.
- The rightmost sets record vertical screen coordinates.
- As for the centre-bottom coordinates, I've yet to identify their role.
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.
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.
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.
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 6
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:
- On the title screen, insert a credit. Hammer the System, Player 1 Start and Player 2 A buttons repeatedly.
This is rather finicky and there's no indication you've succeeded until you reach gameplay. I found good success by assigning Service and P2 A to one key, and then assigning that key and Player 1 Start to buttons on a gamepad using Xpadder and applying the turbo function.
- Make your way to the first mission, and press the Player 2 D & E buttons simultaneously.
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 selects one, and B Button to cancel or exit the menu.
A few options have been shuffled around: the debug dipswitches have been 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). New dipswitches include:
|Freezes the stage timer.|
||ムセイゲン ラッシュ ブラスター
UNLIMITED RUSH BLASTER
|The gauge for the coin-drop score bonus will never deplete.|
|Holding the A button will fire your weapon continuously.
1INT Mode [?]
|Doubles the game speed.|
||Disables all background music.|
||Reduces the timer to zero, killing the players instantly. Will continue to do so until disabled.|
|If enabled, blood will display as red rather than white.
||Changes the level of difficulty.
||ガメンサイズ ベンコウ モード
Shrunk Screen Mode
|Scales the game down to a pixel-accurate screen ratio. This also offers a wider field of view, showing when objects and enemies load in from off-screen.
||タテガメン プレイ モード
Tall Screen (Tate) Play Mode
|Rotates the screen 90 degrees counter-clockwise.
||サュウ ハンテン プレイ モード
Mirror Play Mode
|Flips the screen horizontally (but not the HUD). Directional controls are flipped as well.
|Applies a blurring filter to all sprites.
Super Sampling Filter
|Applies a blurring filter to all sprites.
|Disables dithering; only ever noticeable if you zoom in on sprites.
|Cranks up the brightness to sprite-accurate levels.
||カゲ ヒョウジ OFF
Shadow Display OFF
|Disables all shadows.
Background Graphics OFF
|Turns off all the background graphics.
Fixed Graphics OFF
|Hides all HUD graphics. (don't worry, the debug menu is still visible)
There's also a new menu, ADX / ADX 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.
Metal Slug Advance
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.
VIEW ATTACK RECT
VIEW BODY RECT
VIEW PUSH RECT
VIEW GEO SCROLL A
VIEW GEO SCROLL B
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.
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.
_time_:[ / ]
player:[ / ]
At 00079270 lies these strange English phrases, possible leftovers of debugging information. It notably mentions Morden, whose only appearance in the game is as a portrait in the Mission 5.
|1-01:ﾊｼﾞﾏﾘ ﾊ ｲﾂﾓ ﾄﾂｾﾞﾝ
||The beginnings are always sudden|
|1-02:ﾊｲｷｮ ﾉ ｷﾞﾘﾀﾞ
||Girida-O in the ruins|
||Strange!? A huge Metal Slug?!|
||The hanged man|
|1-05:ｻｸｾﾝ ｶｲｼ ｼﾞｮｳﾘｸ ｾﾖ
||Start the operation, and end it|
|1-06:ﾉﾎﾞﾚ! ﾓｰﾃﾞﾝ ﾉ ｶﾞｹ
||Climb! Morden's cliff|
||The flying boat|
||Harrier aerial battle|
||Harrier indoor battle|
||Boarding the harrier|
|6-30:ﾃﾞｸﾞﾁ + ｶｰﾄﾞ
||Exit + card|
|HOW TO PLAY
||Development test 1|
||Development test 2|
||Development test 3|
stoffhime1 pointed me towards what looks like the extensive remnants of a level select at 0007D8C0. Intriguingly, the listings for Missions 3 and 4 feature three extra screens, adding their respective screen totals to ten and six, even though you don't visit that many screens in those levels. Now if only we could access them!
After the dungeon's listings, there appears to be additional unused screens: four slots for demos (the game features no attract mode!), a How to Play screen (the game offers you no help!), and three "development test" screens. Hm!
Big thanks to candy76041820 for the name translations.
Of course, I'm not talented enough and nobody has cared enough to figure out how to boot up this debug menu, if at all. Any and all help would be madly appreciated!