Metal Slug


First release: April 19 1996 (Neo Geo MVS)

"Blast away and go, go, go!"

A military shooter with lavish attention to detail and a weird sense of humour. Who knew a franchise would come out of this? A sterling action game that set the groundwork for sequels to go nuts with.
Notable for its development history that swerved all over the place, the biggest change of all being its transformation from vehicular-only to fighting on-foot! There's acres of unused graphics related to these early ideas.


[information coming whenever]


At the beginning of the 21st Century, two military groups known as the Regular Army and the Rebellion are at war. The Regular Army is a government- run military force used for various tasks such as peacekeeping and fending off terrorism. The Rebellion is formed by a group of people whose wishes are to change the world-government into a military controlled one.

In 2026, the Rebellion Army launches an assault that pushes the Regular Army forces into the brink of destruction. No one expected this except for the Rebels who came up with these plans. The fault was mostly in the hands of the Regular Army commanding officers, who failed to realize the value of information that the Regular Army intelligence division had provided.

With superior numbers of troops and weapons, the Rebels overwhelmed the Regular Army in all aspects. Seeing their disadvantage to carry out direct attacks against the Rebellion, the Regular Army then decided to carry out numerous special operations and create certain vehicles to accompany their commandos. Not long after, a newly designed tank, code named “Metal Slug”, was forced into production.

The war went on for two years. During those two years, the Regular Army has been stockpiling the “Metal Slug” tanks in their caches with hopes to launch a massive assault against the Rebels and end the war. Things went well until 2028. The Rebellion forces found out and captured many of the caches, along with many of the tanks in them intact. Without those tanks the Regular Army could not even hope to win. And with those tanks under the Rebel control, it was just a matter of time until their demise.

With the government and the military in shambles, Lieutenant Rossi gathers up most of the scattered Regular Army troops he can muster to launch a desperate counterattack. Their mission objective: recapture the stolen vehicles and use them to destroy the opposition. If the vehicles can’t be captured, then destroy every last one of them.

from Metal Slug Anthology manual


The development history of the first Metal Slug is probably the most documented of the series, not just from the sheer amount of concept art, but from a series of videos by Retro Game Test: Metal Slug History Part 1 and Part 2. Credit goes to Youloute (ganked from Gaming Hell), Glowsquid (from NeoGAF posts), and Divison 六 for translations.

Nazca Corporation was formed from members of Irem's then-defunct arcade staff and served as a subsidiary to SNK. Their job was to port Neo Geo games to PlayStation and SEGA Saturn, but demanded to make an arcade game of their own; SNK allowed them to make it in their off-time.

"We thought having normal player characters would be boring, and we wracked our brains for awhile to come up with something different. That was when we hit upon the idea for the tanks. Then, once we made them jump, crouch, and move around, they seemed like living creatures, and we thought this would grab players’ attention."

Meeher, 1999 development interview
(from Shmuplations)

The game was originally played only with the Metal Slug; there was no on-foot gameplay (though human pilots, engineer Phil Gene and Michiko Nakajima, were drawn up before Marco and Tarma were conceived - see Concept Art). With the tank as the central focus, the game was to be a lot more slower-paced, focusing on carefully controlling your sluggish vehicle across short levels that were thick with combat, requiring cautious play. All weapons would fire simultaneously upon a button press, and cannon shells were in infinite number. The crew briefly experimented with a button-based aiming system for the vulcan cannon, though it evidently didn't last long.

The P.O.W.s were originally Regular Army soldiers (coloured in blue, but would change colour to match the player) who, when rescued, would tag along and throw grenades, climb on top to fire a bazooka, or even board a mounted turret if one was handy; Early Footage shows this feature in more depth. Only two soldiers could support the player at a time, but any additional rescued soldiers would be stored as stock, and automatically tag in to replace a casualty. Their additional firepower and option-like behaviour appeared to be a heavy focus in the early level designs.

The visual design was partially inspired by the works of Hayao Miyazaki (particularly his Daydream Data Notes illustrations), though the tone of the game was considered more dark at this point, with little to no humour outside of the characterful soldiers. The stages and overall game length were shorter, with less complex stage designs to account for the Metal Slug's limited movement capabilities. Mission 1 took place almost entirely in dark swamp, and Mission 3 only covered the Rebel base and forest, for instance. Mission 2 was not developed at this point, but the rest of the game appeared visually identical to the finished product.

"In order to create and release a game, tons of ideas or designs are born and destroyed. Actually, in the first title, there was a stage that we had to redraw almost half of the background graphic because it ended up not matching our direction as development progressed."

from Metal Slug Anthology interview

After location testing in Osaka in 1995, the game received a significant overhaul. Marco and Tarma were introduced as the player characters, the soldier P.O.W.s were replaced with the iconic unshaven ragamuffins, and the game's length was extended by SNK's demand to make it more attractive to Neo Geo AES home cartridge buyers. The music was sped up as the "bide your time" gameplay was out the window by this point, though since the soundtrack already been composed, Missions 2 and 3 had to reuse the same track.

With human characters, more platform game elements were incorporated into the level design; Mission 2 was built from the ground-up for this version, along with the first half of Mission 3. Huge chunks of Mission 1 and 3 were also redrawn; all levels received modifications to enemy layouts to account for the new play style, though Missions 4 and 5 were mostly left structurally unaltered.

Unused materials

There are a few unused sound effects in the game's data that are possible leftovers from its early development; credit goes to Ivo for digging these up!
"Bingo!" "Yee-hah!" "Game over" "Here we go!" "Let's go!" "Power-up" "Yah!"

Various voice clips from the announcer. Would these be shouted by the support soldiers you picked up along the way? Other unused sound effects include the merchants' screaming from Metal Slug 2 and two clips of a campfire burning.
Using Nebula Jukebox will often find snippets of music among the sound effects, usually of a single-channel played sped-up, like this rendition of the Mission 2 track. I don't know enough about audio to know if they're genuine unused tracks or just the sound data being read in strange ways, but bits of that track show up a few times throughout the data.

Given its total upheaval during development, there's a lot of relics from its original design buried in the graphics, including a totally different design for the Di-Kokka, remnants of old HUD designs and Slug behaviour, and unique aerial shooting animations for Marco and Tarma that would go on to be frankensteined for other purposes in Metal Slug 5 onward.
There's even partial remnants of the prototype's game design in certain test stages, such as an enemy soldier manning a turret and the Metal Slug's stiff turret. It's possible there's more hidden in the game's data, but unless a way is found to load in different objects, all we can do is speculate!


The Metal Slug Official Guide Book (メタルスラッグ公式ガイドブック) was released in Japan on September 1997 by Keibunsha to tie in with the release of the PlayStation port.

It features maps for each mission and breaks them down into four notable parts, with extra information for bosses, sub-bosses and choke points. It also features information and tips for the Combat School and the PS1-exclusive Another Mission.

The last quarter of the book is dedicated to bonus content, including interviews with Meeher, one of the game's designers, and Mina Tominaga (冨永みーな), the voice of Sophia Greenville.

Ten pages of concept art (or "Establishment Materials") are also included, featuring prototype logos, unused vehicle designs, and even a relationship chart stating why each and every character (including ones never seen or mentioned elsewhere!) want Morden's head on a platter.

Scans can be found at Division 六's website,
6th Division's Den.

Developer Interview

An interview with the game's planner, Meeher (みいはぁ).

Q1 今回の作品を作る上でのコンセプトはどのようなものでしたか?

Q2 PS版に追加要素「ANOTHER STORY」を付けられたのはど`うしてなのでしょうか?また、他にも付けたい要素はありましたか?

Q3 メタルスラッグというタイトル名はどのような意味があるのでしようか?

Q4 開発時、あるいは移植時の面白いエピソードがありましたら教えてくだきい。

Q5 開発陣の方が敵として登場するという噂を耳にしたのですが……。

Q6 捕虜の一人一人にまで名前が付いていますよね。ここまでこだわった理由をお聞かせくだきい。

Q7 コンバットスクーノレに入るとき、生年月日や血液型まで入力するのはどうしてなのでしょうか。

Q8 ソフイア教官のお言葉(特に叱られろとき)が一部で大好評らしい(笑)のですが、何かこだわりのようなものはあったのですか?

Q9 各ミッションのタイトルは、のようにして決まったのでしょうか?

Q10 主人公にナイフを持たせブこのはなぜですか?

Q11 ザコ敵のアクションにちかなり凝っていますが、ここまでこだわった訳をお聞かせくだきい。
企画当初よりデザイナーの方では「戦争モノのアクションゲームにおいて、過去にないくらい細かい動きをする敵兵士を作る」という方針ですすめられました。また、ゲーム的な機能としそは特に必要のないパターンもたくさん用意されていますが、これはひとえに生きて る感じや生活感を出そうとしたものです。

Q12 敵の登場メカのネーミングはどのようにして決まったのでしようか?

Q13 鈴木早智子さんというキヤラが設定にあったのですが、いきなり日本人キャラが登場するのはなぜですか?

Q14 開発者の方々がお気に入りのキャラやメカがありましたら教えてください。

Q15 なかなかうまくなれないというプレイヤーにアドバイスを一言お願いします。

Q16 最後に読者に一言お願いします。

Q1 What were the primary concepts behind the game?
● To make a fun action game with a sense of speed and great visuals.
● Despite its comical characters, we wanted character movement and effects such as explosions to be detailed and realistic.
● An exhilarating and flashy game screen.
● A game anyone can play, to relieve stress through constant firefights without worrying about the little things.
● Players can command tanks with innovative movements, behaving almost like a living creature.

Q2 The PlayStation version had new features such as "Another Story". Were there other elements you wanted to add?
It's dull to just release the same game again, so we added a mini-game mode to explain some of the backstory, as there was spare time between mastering and release. We couldn't add it, but I wanted to include an exclusive drill practice stage for the Combat School.

Q3 What is the meaning behind the name "Metal Slug"?
It's a literal translation of our Japanese words "Tetsu no Namekuji" (鉄のなめくじ, slug of metal). Despite being a tank, it moves across the ground like a creature, a bit like a slug, and we added "metal" as a blunt way of saying it's hard as iron.
We thought maybe it'd be fashionable for the hero mechanics to brand themselves as "mecha slugs". Questionnaires among players said they thought the title was bad, though. Which of us has bad taste?

Q4 Were there any interesting episodes during development?
Back when I was busy developing the arcade version, I was dumped by my girlfriend. When development was ending I was optimistic we could get back together again, but I got jilted again just as I began working on the ports.
Metal Slug is a game of misfortune for me. I wonder if it'll happen again in the Spring. I'm not an interesting guy, by the way.

Q5 I heard rumours the development team appear as enemies...
There are 1000 names for the P.O.W.s, but it was so tiring coming up with names, I borrowed the names of our staff without permission. Maybe that's what you heard?

Q6 Every single P.O.W. is given a name. Tell us why you went that far.
Simply getting score bonuses from rescuing people didn't feel positive, so I thought I'd give them names and ranks. The inital name pool was so small the same names kept popping up, so I prepared to make it reach 1000. I figured, nobody would be stupid enough to do this - it's only a thousand names!
I used a variety of international names to sell the idea that this was a global conflict. I tried to bump it up to ten-thousand names for the console port, but I was disappointed with myself that I wasn't up to the task.

Q7 Why does the Combat School require your blood-type and date of birth?
I wanted the players to project a little bit of themselves onto their player character. That, and I wanted the ID card to convey the feeling of enlisting in the army.
I had wanted Sophia to celebrate events - like the player's birthday or events like Valentine's Day and Christmas - using the hardware's built-in clock, but dropped it as the Neo Geo CD didn't include one.

Q8 I hear some of the instructor's dialogue is quite popular, especially when scolding the player (laughs). Why is she such a critic?
I wanted something to stimulate the player's ambitions, to change the game based on the player's status: giving stern pep talks after training results, and becoming more polite as their rank increases. Although it's naive, I also included elements similar to dating simulators. How'd I do?
Originally we'd wanted a handsome male instructor to be in charge if the player enlisted as a woman, but it couldn't be done, sadly.
By the way, you'll receive an exclusive assessment message if you play the 2-player co-operative training, so please try that. I think I wrote a particularly interesting message, if I do say so myself.

Q9 Was there a reasoning behind the title of each mission?
I likened it to the episode title of an ongoing series. I wanted to give the sensation of, before the last level has even begun, it feels like you're watching the final episode.

Q10 Was there a reason for giving the player a knife?
For war games, I figured a "slash" action was just important as "shoot". I simply wanted to try and defeat soldiers with a knife.
On that note, an important high technique is to kill enemies with the knife, as it awards 3 times the points compared to shooting them.

Q11 The enemy soldiers have quite elaborate actions.
At the start of the project the designer advised us to create enemies that make small, precise movements, unlike in older war games. There are a lot of features and behaviours that aren't exactly necessary, but were my attempt to evoke a sense of life and sentience to the game.

Q12 How did you decide on the names of enemy machines?
We thought along the lines of robot anime when they encounter an enemy mecha they can't comprehend. We figured, the people in Morden's army may understand the meaning, but everyone else won't know what it means - it'd tear my mouth apart just trying to pronounce it.

Q13 Regarding Satiko Suzuki, why suddenly have a Japanese character?
Satiko Suzuki is a girl in a hat who appears in the 1-player ending, seen visiting where her boyfriend died in battle. As stated above, this is a global conflict and people all across the world have died, so it's not uncommon. It just happens to be a Japanese girl the camera pans past.

Q14 Do the developers have any favourite characters or machines?
The all-purpose Metal Slug tank topped the year-round events - Obon, New Years, Christmas... The staff agree, everyone loves it and thinks it's cute.

Q15 Any advice for struggling players?
The game's camera isn't auto-scrolling, so advance at your own pace to get acclimatised to the game. Also, guns aren't your only weapon; grenades are vital if you want to progress.
Don't be afraid to turn the difficulty down in the options menu and make use of the stage select. I recommend trying the Combat School, and be sure to have fun.

Q16 And finally, some words for the readers.
We will continue to make games prioritising what our players enjoy, and we give our best regards.

Credits (Neo Geo)


HIYA! (Takushi Hiyamuta / 冷牟田 卓志)


MEEHER ("みいはあ")
KIRE-NAG (Kazuma Kujo / 九条一馬)


A.KUROOKA (Atsushi Kurooka 黒岡 厚至 )



Credits (SEGA Saturn)


Hidenari Honda
Shuji Yamakawa
Kiichi Kakuta
Tkashi Kinoshita
Yasushi Ida
Kengo Sasaki
Tasushi Jingu
Nahomi Okazaki
Minoru Yoshida
Takahiro Tamaru
Masayuki Fukushima
Toshihiro Masumura


Harumi Fujita

Credits (PlayStation)



浮世亭 (Ukiyotei)








富永 みーな (Miina Tominaga)


株式会社 夢工房 (Yumekobo Co. Ltd.)





SNK第4企画部ALL-STAFF (SNK 4th Planning Division)