Metal Slug 4 (メタルスラッグ4) is a run and gun video game for the Neo-Geo console/arcade platform created by SNK. It was released in 2002 for the MVS arcade platform and is the fourth game in the main Metal Slug series.

Metal Slug 4 retains the same gameplay as previous titles, with the addition of some new enemies, bosses, weapons, several new vehicles and a new bonus combo system.

It was later ported to the Microsoft Xbox and Sony PlayStation 2 along with Metal Slug 5 as a compilation.


From the Metal Slug 4 Xbox manual:

In the year 20XX the world trembles under a new evil:

Cyber Terrorism.

It started with a widespread proclamation across the World Wide Web of the creation and imminent deployment of the 'White Baby' computer virus, capable of breaking through all known security systems and taking control of the central military systems of every country in the world.

The all powerful 'White Baby' was created by a terrorist organization calling themselves 'Amadeus - Ones Loved by God'. The emergency International Anti-Cyber Terrorism Conference, held as soon as the proclamation was deemed a viable threat, called for the extermination of the terrorist group 'Amadeus' and the enhancement of central military systems' security and facilities across the globe. The involvement of the special-ops PF Squad in the plan to wipe out 'Amadeus', including their presence in the computer networks of the world, was officially decided. Thus Marco, Fio, and new members Trevor and Nadia set out to take down the 'Amadeus' organisation, whilst Tarma and Eri set to work creating a vaccine for the 'White Baby' computer virus.

After many hours of laborious recon work the special-ops PF Squad managed to obtain a link-up to a satellite feed displaying a meeting of suspected 'Amadeus' members. However, one of the men present at the meeting shocked all in attendance - it was Morden himself, the devil come back to life, shown clearly on the screen. Further information from a highly reliable source indicated that 'Amadeus' was planning to attack a communications facility in only a few hours' times. Such a facility was capable of transmitting 'White Baby' across the entire world!

Can the PF Squad take down 'Amadeus' in time?

And just what is the connection between the terrorist organisation 'Amadeus' and Morden...?[1]

Upon defeating the Doctor and dismantling his Amadeus Mother Computer, the communications facility begins to self-destruct. Two endings occur whether the player successfully escapes or not:

  • Escaping the exploding facility leads to the rescue of the P.F. Squad from the Regular Army Helicopter. Tarma and Eri reward the player characters with a large feast where the guests of honor quickly gain weight.
  • Getting caught in the explosion leads to the player characters inside of a Regular Army medical clinic nursed by Rumi. Tarma and Eri come with get well gift baskets which the bandaged characters accept with a large grin.

After the credits roll, a surviving Amadeus computer starts to transmit data. The computer immediately shuts down once transmission is complete. Whatever happens next is unclear.

New Features

  • New Characters: Tarma Roving and Eri Kasamoto are downgraded to NPCs. Replacing them are newcomers Trevor Spacey and Nadia Cassel. They both sport different melee weapons to attack: Trevor kicks enemies using his Knife Boots while Nadia wields the Stun Gun.
  • Two Machine Guns: Allows players to carry two sub-machine guns with rapid firing. However, the 2H crates are very rare in the game and only have 200 shots like the Heavy Machine Gun. Marco, Trevor, and Fio have unique victory animations should they complete a mission with a 2H in hand.
  • Monkey Transformation: In Mission 1 and Mission 6, there are scientists with rifles. These are loaded with special chemical that transforms characters into monkeys similar to Utan. Players gain a much stronger jumping ability and are able to hang on the bars over their heads. Their pistol also turns into an Uzi. A disadvantage of being a monkey is one cannot pickup any other weapon, and they move slow. Players can be transformed back into human form by picking up an antidote dropped by scientists. Players who are hit by another chemical shot or by the attacks of the Rebels while in monkey form will die.
  • Metallish System: By collecting a White or Blue Emblem, a blue bar appears under their score. The character who picked it up can earn medals by racking up points, and these medals change color as the points collected increases. Bonus points are given depending on the number of colored medals saved at the end of a mission. Note that this fever stops or is nullified when boarding a Slug.
  • Increased Slug Defenses: Slugs take four hits instead of three in this game and Metal Slug 5.


Returning from the previous game are the SV-001 and Slugnoid. Four new vehicles make their debut:

  • M-15A Bradley: First appeared in MS2 as an enemy rocket shooting vehicle, it is equipped with powerful rocket shots and a Vulcan cannon like the Slugs. Players can use it after killing the enemy soldier inside of a blue colored Bradley. However, this vehicle has a very short jumping range and crouches much slower than the other vehicles, and lacks invincibility frames from enemy damage to an in-game bug. The Bradley is colored green.
  • Metal Crow: First appeared in MS1 as the "Melty Honey" under the control of the Rebel soldiers. It appears with the Bradley in Mission 2 in a two-player game and at Mission 5 alongside the Forklift. The Metal Crow is colored blue. It uses a Vulcan and high speed missiles. It is equipped with a blade-covered shield that protects the tank for five hits and also shreds enemies.
  • Walking Machine: Mechanical version of the Mutated Soldiers from Metal Slug 2/X. Much like the animal Slugs in the previous games, it provides no protection to the player. The Walking Machine has a slightly better jumping ability, and its slight lift allows weapons, such as a rolling bomb, to go under the player without harm. It appears in Mission 4.
  • Forklift: Appears in Mission 5 with the Metal Crow. Like the Drill Slug from MS3, it can lift itself up by pressing the jump button. It can stab enemies and destroy vehicles with the fork at the front by pressing the bomb button. The Forklift does not have a Vulcan cannon; rather, the player uses whatever weapon they have. The player is always exposed to enemy attacks.

The players also take assistance of three different Regular Army vehicles:

  • RA-TTT: A Regular Army truck that transports the players to the next mission. Tarma helps the players inside of the truck at the top route of Mission 1.
  • Landseek: A Regular Army version appears in Mission 2 ridden by a POW. Both characters ride on top of it during a rail-shooter section. They cannot fall off the vehicle until the POW stops driving.
  • Regular Army Helicopter: A blue-colored Hi-Do mandated by Eri. In Mission 6, the characters descend using ropes connected to the helicopter. In this state, the players act as if they were scuba diving, so they cannot aim up or down. They also move slower horizontally than vertically.

Missions and Bosses

1 "Let's Run Through!" Brave Guerrier Let's Run Through!
The Scene of a Hard Battle
2 "Show Spirit" Toschka Dalanue Show Spirit
3 "Snowy Road" The Iron Snowy Road
The Scene of a Hard Battle
4 "Cadaverous" Big John Cadaverous
The Scene of a Hard Battle
5 "Go Ahead!" Sea Satan Go Ahead!
6 "Secret Place" Allen O'Neil
Amadeus Mother Computer
Secret Place
The Scene of a Hard Battle
Uncanny Laugh
Final Madness

Development history

Metal Slug 4 is product of a joint-venture between Mega Enterprise, a Korean game publishing and distribution company, and Noise Factory, a Japanese company focusing on creating musical scores.

When SNK declared bankruptcy, Mega Enterprise still retained its rights to distribute several of SNK's titles within Korea. Mega went a step further by acquiring the authorization to continue to produce several of SNK's titles, primarily the Metal Slug series, which was very popular in South Korea.

Since Mega Enterprise did not have the technical expertise to produce a game from scratch, they grouped together with Noise Factory, which helped to make the soundtrack of the game and several programming and design concepts. Metal Slug 4 was created using Metal Slug X as the base. After spending approximately 400 million won (approximately US$400,000), Metal Slug 4 was finally released in December 2002.

Bugs, Glitches, and Oddities

Nadia's separated sprite.

  • The Bradley and Metal Crow do not become invincible after being hit, unlike other Slugs. This makes it very vulnerable, especially to the MH-6J Masknell which can fire three shots at once.
  • The death screams of zombiefied Marco and Trevor are switched.
  • Fio uses Eri's death scream in this game.
  • Both new characters have glitches with their melee attacks:
    • Trevor mobility is massively hindered while he is performing it which makes him vulnerable.
    • Nadia will only score 100 points from a melee attack while standing (which awards 500 points for every other character). Nadia scores 500 points only when a melee attack is done while sitting or crouching. Her Stun Gun can also damage an enemy vehicles and other destructible objects.
  • Nadia's sprite glitches out when performing a standing melee attack while equipped with the Two Machine Guns. Nadia's upper half moves back, almost separating from her legs, and comes back when melee attack is finished.
  • Trevor and Nadia's weapon muzzles are colored differently. Trevor's muzzle is white while Nadia's is red.


Flyers and covers


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Metal Slug 4
Heroes Marco Rossi | Fio Germi | Trevor Spacey | Nadia Cassel
NPCs Tarma Roving | Eri Kasamoto | POW (Names) | Rumi Aikawa | Madoka Aikawa | Hyakutaro Ichimonji | President | Donald Morden | Allen O'Neil | Doctor | Rebel Army | Amadeus Syndicate | Shop Lady | Lumberjack | Bear | Haunted House Employees | Haunted House Attendees | Miners | Sailors
Enemies Rebel Infantry | Amadeus Infantry | Fanatics | Grenade Soldier | Bazooka Soldier | Shielded Soldier | Bikers | Rebel Rifleman | Mortar | Gatling Soldier | Hazmat Soldier | Pirates | Scientists | Sasquatch | Mummies | Dog Mummy | Chariot | Zombies | Tar Man | Supervisory Camera | Patrol Robot | Morden Robot | Amadeus Robot
Enemy Vehicles Di-Cokka | M-15A Bradley | T-2B Melty Honey | MV-280B | Nop-03 Sarubia | Girida-O | Turrets | Parachuetruck | 3-ton Utility Truck | R-Shobu | MH-6S Masknell | Flying Tara | Eaca-B | Hammer-Yang | Landseek
Bosses Brave Guerrier | Toschka Dalanue | The Iron | Big John | Sea Satan | Amadeus Mother Computer

Mecha Allen

Weapons Heavy Machine Gun | Rocket Launcher | Shotgun | Flame Shot | Enemy Chaser | Iron Lizard | Super Grenade | Drop Shot | Two Machine Guns | Grenade | Fire Bomb | Stone | Thunder Cloud
Slugs SV-001 | Slugnoid | Bradley | Metal Claw | Walking Machine | Forklift | Motorcycle | Landseek | Regular Army Helicopter
Missions "Let's Run Through!" | "Show Spirit" | "Snowy Road" | "Cadaverous" | "Go Ahead!" | "Secret Place"
Other Metallish System | Transformations | Items | Environmental Objects | RA-TTT | Hoist
Metal Slug Series
Main Series Metal Slug: Super Vehicle-001 | Metal Slug 2/(X) | Metal Slug 3 | Metal Slug 4 | Metal Slug 5 | Metal Slug 6 | Metal Slug 7/(XX)
Spin-Offs Metal Slug: 1st Mission | Metal Slug: 2nd Mission | Metal Slug Advance | Metal Slug 3D | Metal Slug Tactics
Tower Defense Metal Slug Defense | Metal Slug Attack | Metal Slug Infinity
Mobile Metal Slug Mobile | Metal Slug Mobile Impact | Metal Slug: Allen's Battle Chronicles (Mobile 3) | Metal Slug Mobile 4 (UMS: Login) | Metal Slug Soldiers (UMS: Tank Conspiracy) | Metal Slug Fighters (UMS: Fierce Battle) | Metal Slug Warriors (UMS: Triumph) | Metal Slug STG | Metal Slug Mars Panic! | Metal Slug Tactics | Metal Slug M1 | Metal Slug M2 | Metal Slug 2013 | Metal Slug Team Mission | Metal Slug: Awakening | Metal Slug: Commander
Pachinkos Metal Slug Type-A | Metal Slug SV-001 | Metal Slug 3 (Pachinko)
Compilations Metal Slug 4&5 | Metal Slug Anthology | Metal Slug Complete PC | Arcade Archives | Neo Geo Pocket Color Selection
Cancelled / Discontinued Metal Slug (GBA) | Metal Slug Zero Online | Metal Slug Touch | Metal Slug Revolution | Metal Slug Wars | Metal Slug XX Online
Prototypes Metal Slug Advance
Related Titles
Cameos / Crossovers The King of Fighters '99 | SNK vs. Capcom: The Match of the Millennium | The King of Fighters 2000 | SNK Vs. Capcom: CHAOS | Neo-Geo Battle Coliseum | The King of Fighters: Maximum Impact 2 | SNK Vs. Capcom: Card Fighters Clash | SNK Vs. Capcom: Card Fighters DS | Days of Memories 2 | Neo Geo Heroes: Ultimate Shooting! | Battle Cats | RPG! Sister Quest | Jetpack Joyride | The King of Fighters XV
Ikari Warriors Ikari Warriors | Victory Road | Ikari III: The Rescue | Ikari: Leona Gekitohen
Irem Games
Irem's D.A.S. Universe

Air Duel | Undercover Cops | In The Hunt | Gunforce II

Books Metal Slug: The Ultimate History | Metal Slug Attack Official Artbook
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