Trivia / Metal Slug

• B-Team Sequel:
  • Thanks to SNK's bankruptcy, Metal Slug 4 was farmed out to Noise Factory (the people who composed the music for Metal Slug 3) and the short-lived MEGA Enterprises. ME mostly wound up simply recycling the assets and backgrounds from past games (even the bosses are cobbled together from old sprites), which in combination with the rather poor level design in areas led to complaints that the game feels less like a proper Metal Slug entry than it does a "tribute" or "ROM hack."
  • Metal Slug 5 was developed by Noise Factory as well, but SNK took control late in development and revamped it. See Troubled Production below.
  • According to developer Hidenari Mamoto, all games after Metal Slug 3 were developed by Noise Factory members.
  • Metal Slug Anthology was ported by Terminal Reality. Yes, that Terminal Reality.
  • In a series first, the development of Metal Slug Tactics was handled by the indie company Leikir Studio, with DotEmu on publisher duties.
• Cancellation:
  • Metal Slug Wars was an RTS released for iOS around early 2013 and removed from the store within the same year. Most of its assets and music were transferred to Metal Slug Defense.
  • Many Chinese and Korean Metal Slug mobile games tend to close down after a couple years in service.
• Dueling Works: Incidentally, the fourth game was released in 2002, alongside the Metal Slug-clone Demon Front. Both games were made outside of Japan (MS4 by Korea, DF by Taiwan) and shares similar aesthetics, enemy designs and animations (though the latter lacks POWs that can be rescued).
• Dummied Out:
  • A large number of things, most notably in Metal Slug 5. You can check a more detailed observation of said elements here.
  • Metal Slug X has a ton of unused areas from the first game, missions and enemies from 3 in development, and new locations and sprites created for this game alone. This is because X was originally going to be a remix of the first two games using the engine of 3, but only Metal Slug 2 was remade. In addition there is also an unused animation for a rebel soldier being bisected vertically.
  • Metal Slug 3D has most of its text localized and can be accessed through cheats. Text positioning is somewhat glitchy but is legible.
  • Sprites of Abul attacking and setting up his white flag are present in 2's ROM. These get their use in Defense and Attack.
  • A nearly complete set of unused sprites is present in Metal Slug 5. Most of them are given use in Attack. For example, a guerilla having an additional death animation where they lay flat on the ground,^note Their corpses can be found in Mission 1's temple positioned this way but unused in normal gameplay a Ptolemaic Flying Tara being more in line with 1's version, a sniper using a proper crouched death animation and is able to fire their rifles in a standing and crouched position, the Screamer's captain throwing something, etc.
• Follow the Leader: Metal Slug's success in the mid-90s have renewed interest in the Run-and-Gun genre, which has since declined ever since the late 80s, with a few imitators following suit in the next decade. Notably, the Taiwanese Metal Slug clone Demon Front, Dolphin Blue, the CT Special Forces series and the made-in-China Commando: Steel Disaster (whose protagonist is a blatant Captain Ersatz to Marco).
• He Also Did: Eric Summerer, the voice actor for Marco in 3D, is known for his contributions to the board game group, The Dice Tower.
• Keep Circulating the Tapes:
  • Metal Slug Advance and Metal Slug 3D are the only non-mobile games that have yet to be re-released.
  • Metal Slug 7 is only available for the Nintendo DS. It was originally going to be re-released for the Xbox 360 but was replaced by Metal Slug XX.
• Milestone Celebration:
  • Metal Slug 6, 3D, and Anthology are dedicated for the 10th anniversary of the franchise.
  • Similarly, Metal Slug Attack represented the series' 20th anniversary.
• No Dub for You:
  • The Japanese versions of Metal Slug 1 and X for the PlayStation and Saturn had their respective Combat School instructors speak in full sentences. While the former port never came out West, the latter one did, yet the instructor is silent throughout.
  • In the inverse, 3D only has an English dub but was never released internationally.
• No Export for You:
  • The 3D installment for PlayStation 2 is Japan-only, despite having exclusively English voices intended (but cancelled) for exporting the game.
  • The sixth game's Combat School is the only version who never came out West. Their school instructors eventually made cameos in Metal Slug Defense.
• Port Overdosed: SNK just loves re-releasing the original trilogy and X. Especially ridiculous with 3 on PlayStation 4 and Xbox One, where there are two standalone versions on both consoles.
• Prop Recycling: Present to varying extents in all the sequels, but 4 is especially egregious in that almost everything is a recycled asset; even the bosses are reused sprites cobbled together and recolored. This is also a criticism of 5, although it is not as noticeable (outside of a room where the mechs in the background have the wrong faction markings) since the bosses are new and the sprite edits are generally more creative than simple recolors.
• Referenced by...:
  • The second boss of Not Dying Today, a Super-Zombie Nurse, has a bloody vomit attack covering a massive chunk of the screen, which is directly lifted from here.
  • The "Metal Slug" is an equippable item for the Fusilier class in Vambrace: Cold Soul.
• Schedule Slip: Metal Slug Tactics was moved from its planned 2022 release into 2023, for quality assurance (or, as the Twitter announcement put it, to make it "as explosive as possible").
• Troubled Production:
  • Metal Slug 5, originally being developed by Noise Factory, was almost nearing completion. SNK took over late in development and revamped the game completely, but were forced to rush the overhauled game out prematurely in order to begin development of Metal Slug 6 for the new Atomiswave arcade board.
  • The GBA port of the first Metal Slug was criticized during development demos due from poor implementation. It was later cancelled due to memory limitations and the fact that Metal Slug Anthology was also being released. GBA ports of 2 and 3 were planned as well but went under from the cancellation of the first port.
• What Could Have Been:
  • Early versions of Metal Slug 2's arcade flyer ([1]◊ [2]◊ [3]◊) had Fio as a blonde and Eri as a brunette before swapping their hair colors at the final release◊.
  • The original version of the first Metal Slug, which was actually completed and location-tested at SNK's Osaka location, was a very different game (being part of the Dark Anarchy Society saga, rather than set in its own universe). The history of this versions is extensively detailed in this French video, which also contains screenshots and the original background art for it:
    • The entire game was played with the SV-001 Slug. There was no on-foot gameplay and Marco and Tarma did not exist at this point.
    • Before Marco and Tarma became a reality, two different characters (one looking similar to Fio) were meant to be the main protagonists.
    • The original plot was that General Morden (who is a clear villain here, rather than a Tragic Villain) had spent years planning a coup and managed to conquer all of the world’s major cities in his opening salvo. The original player character, Phil John, was an engineer for the Regular Army who was working on the Metal Slug prototype, and took it with him to join the resistance. Player 2 was a gold Metal Slug piloted by one named Michiko Nakajima.
    • The tone was more somber and lacked any humour, being more in line with the developers' work on In the Hunt.
    • The backgrounds were redrawn. For example, the entire first stage, and not just the second half, was set inside a swamp.
    • The game was much shorter: Stage 2 did not have an equivalent in the original version, and levels were shorter and simpler (for example, level 3 did not have the climbing portion or a mid-boss battle). The game was lengthened at SNK's instance, their reasoning being that since the Neo Geo was also sold as a home system, the game should be of reasonable length.
    • The iconic POWs originally were white palette swaps of Morden's infantry. Furthermore, instead of giving items, rescued POWs would either climb to the top of the Metal Slug and fire their bazooka, or stay next to it and throw grenades.
  • The dancing Rebel Army soldiers seen in the 2-Player ending of 1 were supposed to be the soldiers from the Regular Army in a white uniform, as seen here.
  • The above video also reveals that rearranged themes from Metal Slug 1 were composed for X and are still present in the ROM, that an "X" version of Metal Slug 3 was planned, and that the antagonists of Metal Slug 4 (as developed by SNK) would have been fish-people. The last part is actually corroborated by the ending of Metal Slug 3 where the Final Mission's backup character hurls their handgun in the ocean to symbolize that it is the end... Only for the gun to fall on the head of a fishman on its way down. Original plans were using that gag screen as the plot hook.
  • Metal Slug X was originally a remix of both 1 and 2 featuring pathways and new locations that intertwined the games' missions. Eventually only 2 was remade with disappointment from the developers. The ROM has various unused locations and exit pointers. Metal Slug 1 also had their music remixed, however only Mission 1's theme made it in for the credits. SNK and the game's composer have the rest of the unused remixes.
  • Many ideas and models were scrapped from the final product, especially in 5. Including a giant turtle-like mecha and the native zapped by the lightning at the beginning as the final boss on a levitating, laser-spitting pillar. See this page for all the stuff that people have found from the game files. Some of these get their time in the sun in Attack. The guy on the Pillar is Ptolemaios, and the Stone Turtle is a Rare-quality unit.
  • 3D, having exclusively English voices, was planned for export under the title Metal Slug 2006, also to celebrate the franchise's 10th anniversary, before getting cancelled due to very-negative reviews, and SNK decided to release Anthology instead.

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