Unseen Objects

A big cheers to Mr_Beacon00 (信标先生) for working out a way to see these! His code replaces the first prisoner in the second screen (2:3) of Mission 2 with whatever object ID is assigned. To see these for yourself, it requires the usage of Cheat Engine 6.83 and this .CT address table. It's optimised for use with WinKawaks 1.65.

To use:

If there are numbers under the Values column, success!
If not, double-click the Address of the cheats and confirm that the .EXE file under Pointer matches the .EXE at the top of Cheat Engine's window. If the Address is "WinKawaks.EXE" but the window says "WinKawaks 1.65.EXE", you'll have to add that "1.65" to it!

The first code ("Object ID") will modify the object ID of the prisoner at the start of area 2:3 in Mission 2, while the second code ("Object ID 2") changes the stone pillars in unused area 3:E, but only before the level has loaded; no change will occur while the object is on-screen.

"Obj ID" is the core object, while "Obj Sub ID A", "B", etc., are modifiers that vary from object to object; some will change enemy behaviour, some determine what objects crates and prisoners are holding, movement speed, direction, and other properties.
The Obj ID increases in increments of 4 - setting the value to anything in between will crash or freeze the game.
For best results, reload the area using the debug menu's stage select and set all Sub IDs to 0.

ID: 296

An unused gold variant of the Ptolemaic robots, accompanied by a cultist on a hover platform. The robot is invincible until the cultist is harmed, at which point the robot can be destroyed with two grenades.
The cultist will fire a shot in retaliation if shot once, though the platform can be destroyed in only three pistol shots; the cultist will then run right off-screen and cannot be harmed. The cultist's animation and hover platform are seen in area 5:4, but cannot be harmed or interacted with in-game.

ID: 344, 348

Variants of the hover jets seen in the first area of Mission 2. These simply fly straight up or straight down off-screen, but can be shot and destroyed. The vehicles seen in-game cannot be interacted with.

ID: 456

The personnel van with an unused cannon on top. It drives a set distance and then stops, and the cannon runs through its three firing animations. Sub-ID A will change its direction, but the cannon always faces right. The van has no collision detection and can't be destroyed, and the cannon is purely for show; it cannot fire projectiles.

ID: 460

Setting Sub-ID A to "1" will have the Ptolemaic speedboat always stay ahead of the player, firing missiles that drift backwards. The pilot plays an unused animation with this variant. In-game, they only ever use Sub-ID "0" and stick to the left side of the screen.

Setting Sub-ID A to "2" will feature an unused faraway sprite for the speedboat, which zooms off the right of the screen and returns as the variant above.

ID: 564

An unused companion character! There's a lot of funky beliefs about this character over the years, so let's state the facts.

the character is unused

I mean, duh. He never shows up in any of the missions, nor is he reinstated in the console ports. The closest he's gotten to an official 'appearance', so to speak, is on one of the game's promotional flyers. He otherwise only appears in testing areas not intended to be seen in normal gameplay.

the character's coding is incomplete

It seems that way, at least. The character is a prisoner who will join your side when rescued, similar to the likes of Utan or Hykutaro, following behind the player wherever they go. If the player is stopped, he'll stand behind them and fire if enemies are present.His projectile is nonfunctional, appearing as a slow-moving discarded machine gun; it will explode upon touching terrain, but does not harm or react to enemies.
The character counts as a prisoner when rescued, but does not appear on it visually, as is usually the case for special rescues like Rumi Aikawa, etc. He functions on a basic movement level, but he's missing a lot of necessities to make him a useful, functional addition, and no code relating to some of his animations found in the sprite viewer.

the character has no official name

The character has no preset name on the prisoner list; rescuing the characer and completing the stage will display a random name and generic prisoner, as with any other P.O.W. There has yet to be concept art unveiled for this character (if any), nor has he been repurposed for the likes of Metal Slug Attack. Unless there's an internal object ID that might shed light, he's otherwise nameless.

I personally dubbed the character "Glen Achilles" back in 2004/2005, naming after "Achilles", the random name chosen for the prisoner list in that instance, and "Glen" for the first person I could think of who had a moustache. This has since been accepted as 'fanon' among the community, except the Metal Slug Wiki referred to him as "Acchiles" for years because some motherfuckers need to learn how to spell. This is unofficial and Metal Slug: Missing in Action does not endorse adopting any bullshit names we apply to unused elements as official.

ID: 568

This ID belongs to the fleeing civilians from Mission 3 and 5. Changing Sub-ID A to "1" will show the injured bloke, and "2" will feature the little kid who runs at a crazy speed.

ID: 656

A stationary blob of slime. Pretty durable, as it takes 4 grenades to destroy. Players will slowly slide off it if they stand on it. No idea what it could be used for.

ID: 664

A stone pillar with a stylised skull engraved on it, undoubtedly intended for Mission 1. Its collision detection is wack, consisting of two hitboxes stretching far beyond the pillar's actual sprite. It degrades when shot, but has no sounds or special effects associated with it - it simply vanishes when destroyed with no explosion or debris.

ID: 716, 720

A log bridge in medium and large variants. Can be walked on by players and enemies. Destroyed when shot once. Seems a good fit for Mission 1 or 2.

ID: 768

Garbage that slowly drifts to the left, likely intended to set the mood in Mission 5. Changing Sub-ID A will change the object, from plastic bag to tin can to newspaper.

Item IDs

Items can be changed by setting the object ID to an item container, like the box (48) or treasure chest (52), and then changing Sub-ID A.





ice cream



hot dog


bird - standing



message in a bottle

goldfish bowl

goldfish bowl - shattered

necklace / dog tags






mobile phone


fire extinguisher

There's a whole rake of unused items that award either 100 or 200 points.

The IDs below are listed in decimal.

0 Metal Slug
4 Metal Slug Type-R
8 Metal Slug - facing left
12 Metal Slug Type-R - facing left
16 Slug Flyer
20 Slug Mariner
24 Slug Mariner
28 Car slug
32 Slug Gunner
36 Slug Gunner
40 Spider Slug
44 ?
48 box w/ item
52 treasure chest w/ item
56 box w/ item
60 treasure chest w/ item
64 gas mask soldier
68 gas mask soldier
72 bandana soldier
76 gas mask soldier
80 gas mask soldier
84 bandana soldier - swing in on vine
96 gas mask soldier - alarm horn
100 gas mask soldier
104 bandana soldier - shield
112 R-Shobu
128 gas mask soldier - grenade
132 native
136 bandana soldier - mortar
140 Landseek
148 Sarubia
152 Sarubia - cannon
156 Landseek - raised platform
160 sea mine
164 sea mine?
168 gas mask biker
172 gas mask biker - wheelie
176 gas mask biker - rocket sidecar
180 gas mask biker
184 gas mask biker - throws grenades
188 Girida-O
220 bandana soldier - bazooka
232 gas mask soldier
236 bandana soldier
240 gas mask soldier
244 gas mask soldier
248 bandana soldier
252 bandana soldier
256 sniper
260 sniper - prone
264 sniper - under box
268 sniper - under bush
272 officer
276 officer
280 native
284 native with axe
288 native
292 cultist
296 robot + cultist on floating platform UNUSED?
300 cultist on floating platform
304 plane
308 plane
312 Masknell
328 Di-Kokka
332 Di-Kokka
336 submarine
340 submarine
344 hoverjet - flies down, destructible
348 hoverjet - flies right, destructible
352 ?
356 hoverjet - static
360 robot - one-handed shot
364 robot - two-handed shot
368 robot - static
372 robot - rocket launcher
376 robot - static, non-interactive
380 robot w/ spiked mask
384 robot w/ spiked mask - static
388 robot - chaingun
392 robot - chaingun, static
396 robot - claws, jumps to player
400 robot - claws, endless punch combo?
404 spider robot
408 spider robot
412 Girida-O turret mod
416 Girida-O cannon mod
420 Girida-O turret mod
424 Girida-O cannon mod
428 Black Hound
432 hoverbike
452 van - static
456 van - driving w/ cannon UNUSED
460 speedboat
464 long rocket
468 ?
472 big jellyfish - static
476 big jellyfish - moving
480 electro jellyfish
484 squid
488 diver
492 native destructible stone gate (mission 1)
496 ?
500 flame spurt (mission 1)
504 pink grub
508 ?
512 pink grub
516 ?
524 bat
528 bat
532 POW - tied up
536 POW - hanging
540 POW - tied to post
544 POW - free
548 glasses POW - tied up
552 glasses POW - hanging
556 glasses POW - tied to post
560 glasses POW - free
564 gun-wielding POW
568 fleeing civilians (Mission 3)
572 Rumi Aikawa
576 Madoka Aikawa
580 sandbag
584 flat sandbag (MS1 leftover)
596 ?
600 make player walk to invisible object, possibly Mission 5 intro
604 ?
608 ?
612 ?
616 destructible wall-gate
620 building access lifts (Mission 3)
624 side of wall foreground detail
628 barred door background detail
632 elevator (MS3 leftover?)
636 pipe (Mission 3)
640 glass window (Mission 3)
644 underwater tunnel (Mission 4)
648 wooden stop sign WHERE??
652 spotlight tower (mission 4)
656 green blob UNUSED
660 POW on raft - static
664 skull stone tower UNUSED
668 ground patch (Mission 1, used in 1:2)
672 ivy tower bg detail
676 Mission 2 cutscene
680 ceiling (Mission 1)
684 destructible fallen pillars (Mission 1)
688 S.V.W. crate, contains Slug Gunner
692 remove background, kills most enemies...?
696 ?
700 explosion?
716 log bridge UNUSED
720 longer log bridge UNUSED
724 ?
728 elevator (Mission 2)
732 elevator wall debris (Mission 2)
736 runway light (Mission 2)
740 cloud (Mission 2)
744 stone tower platform, non-interactive (Mission 5)
760 building access lifts, non-interactive (Mission 3)
764 rounded platform (Mission 5)
768 plastic bag UNUSED
772 stone tower platform (Mission 5)
776 ?
780 ?
784 POW - free
788 POW - free
792 ?
796 ?
800 ?
804 ?
808 barrel
812 crate platform
816 big crate platform
820 Regular Army truck (Mission 3)
824 glass window, destructible (Mission 3)
828 Slug Gunner repair station + 2 gas mask soldiers, Slug Gunner
832 box (Mission 2)
836 bush (Mission 2)
840 water droplet effect
844 water droplet effect
848 gas mask soldier - dead
852 gas mask soldier - bowing, flees
856 ?
860 ?
864 ?
868 bubbles
872 ?
876 ?
880 animation test
884 composition test
888 ?
892 Mission 3 boss
896 Mission 4 boss
900 Mission 1 boss
904 Mission 2 boss
908 HUD coordinates?
912 ?
916 Mission 5 final boss
920 Spider Slug
1012 ?