Metal Slug's Hidden Origins Revealed by Director Kazuma Kujo
The revelation that Metal Slug (1996, Neo Geo Multi Video System / MVS) was initially conceived as Metal Slug Zero, a vehicular combat game without human protagonists, offers a rare glimpse into the iterative design process of a foundational run-and-gun title. This detail, shared by director Kazuma Kujo, underscores the significant changes a game can undergo before its public release.
Kujo's insights, gathered over multiple interviews including a substantial three-hour session in Tokyo, provide a clearer picture of Metal Slug's development. The game, now a beloved series, had its credits obscured by pseudonyms for over a decade. Kujo himself was credited as "Kire-Nag" in the original release.
Unmasking the Creators Behind the Game
The identities of Metal Slug's developers remained largely unknown until around 2008. A breakthrough came when Ollie Barder, a contributor to Time Extension and mecha expert, interviewed Kujo about R-Type Final. While Metal Slug was not the primary topic, Kujo's portfolio listed the game, initiating a long process of discovery.
Further efforts, including an email interview for Retro Gamer magazine issue #98 and later extensive in-person discussions, gradually brought the team's story to light. Kujo's career began at Irem in 1989, where he worked on titles such as R-Type II as a tester, despite his self-professed lack of skill in shooting games.
The Irem Legacy and Pseudonyms
Kujo's early work at Irem included Shisenshou: Match-Mania (1990, Game Boy), Air Duel (1990, Arcade), and Superior Soldiers (1993, Arcade). He then directed In The Hunt (1993, Arcade), known in Japan as Kaitei Daisensou (Underwater Great War). The use of nicknames like "Tsumi-Nag" and "Oni-Nag" at Irem was common, a practice Kujo attributes to the closed nature of Japanese game companies at the time, which often prohibited staff from using their real names in credits.
Kujo explained that his own changing nicknames, such as "Oni" (ogre or demon), "Kire" (anger or snapping), and "Tsumi" (sin or wrongdoings), reflected his frustrations as a young developer. This practice of pseudonyms, while common, made tracing the lineage of games like Metal Slug particularly challenging for historians and enthusiasts.
From Irem's Demise to Nazca Corporation
The true origin of Metal Slug lies with the staff of Irem's Osaka branch. When Irem announced its withdrawal from the gaming business, over 100 developers sought new opportunities. A group of about 15, including Kujo, received funding from SNK to establish Nazca Corporation. This move was significant, as SNK had previously been a rival to Irem.
Kujo shared with Bitmap Books, whose Metal Slug: The Ultimate History (2019) integrated much of this research, that adjusting to making games for a former competitor was challenging. SNK, however, showed respect for the Nazca team's independent spirit, allowing them to operate from a separate building. This arrangement helped preserve the team's unique development culture.
The Design DNA of Metal Slug
The design lineage of Metal Slug is not primarily from Contra, as might be assumed, but rather from three key Irem titles: Kujo's In The Hunt, Meeher's Undercover Cops, and Geo Storm (also known as Gun Force II), which involved Meeher and other future Nazca staff. Metal Slug inherited both the aesthetic and the design philosophy of these earlier works.
Kujo and co-designer Meeher split the level design responsibilities for Metal Slug. Meeher, known for games with stop-and-shoot segments, designed levels that progressed in distinct, segmented areas. Kujo, whose background included side-scrolling shooters like In The Hunt, created levels that maintained continuous scrolling. This alternating design approach provided variety within the game's stages.
Meeher's Approach to Level Design
Meeher, speaking directly about his method, emphasized the importance of "novelty" over imitation. He detailed his considerations for simultaneous two-player action, particularly regarding respawn mechanics versus checkpoints. Respawning, he noted, works well for multiplayer, allowing players to see more of the game and encouraging multiple credit insertions.
However, Meeher also acknowledged the potential for "rough edges" with respawning, where players might exploit invincibility frames. His preference was for a system that made sense within the game's overall design, ensuring enemy placement and difficulty adapted to player deaths to maintain a dynamic and dramatic experience upon respawn.
The Genesis of In The Hunt
Kujo's inspiration for In The Hunt came during a park nap, leading to its distinctive underwater theme. This setting allowed for novel gameplay mechanics, such as vertical weapons affected by water physics, creating a unique, delayed sensation. Players had to contend with enemies across air, surface, and underwater environments, often navigating intricate scenery.
This approach was fresh in the 1993 arcade landscape, preceding the widespread adoption of danmaku (bullet hell) shooters. The highly animated mechanical designs and slower, vehicular combat of In The Hunt directly influenced the initial concept of Metal Slug, which, as Kujo revealed, began as a tank-only game.
The Transformation of Metal Slug Zero
Nazca spent 18 months developing Metal Slug Zero as a purely vehicular combat game. However, two location tests yielded poor customer response. This forced a significant redesign, adding another six months to the development cycle. The most challenging aspect was changing the player configuration from solely controlling a combat vehicle to featuring human soldiers.
Kujo recounted the internal debate: management and many staff members wished to retain the tank as the primary character. Kujo, however, felt the tank was too difficult to manipulate as the central focus, especially compared to submarines in In The Hunt. He proposed adding soldiers, leading to a substantial discussion within the team. The company director ultimately approved the inclusion of human characters, Marco Rossi and Tarma Roving, transforming the game into the Metal Slug known today. This hints at the critical role player feedback from location tests played in shaping arcade titles, even leading to fundamental shifts in core gameplay.
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Originally announced by SNK Corporation · first reported by Time Extension.
