In the summer of 1987, Japanese arcade trade magazine Game Machine carried a full-page advertisement for a new science-fiction shooter from Irem Corporation. Its title, R-Type, appeared beneath a grotesque creature emerging from a swirling alien landscape. Screenshots showed enormous enemies, strange weapons, and the small R-9 fighter that players would guide into the Bydo Empire. At the bottom, beside Irem’s corporate information, appeared a phrase that seemed to summarize the company’s ambitions: “Innovations in Recreational Electronic Media.”
By then Irem had already built an international reputation. Moon Patrol had crossed the Pacific through Williams Electronics. 10-Yard Fight had moved from Japanese arcades into Nintendo’s early home-console library. Kung-Fu Master had helped define a new style of scrolling action game. Yet R-Type became something larger. Its art, difficulty, level design, charge shot, and detachable Force weapon produced one of the most recognizable arcade shooters of the 1980s.
The history behind those games is more complicated than the familiar Irem logo suggests. The Irem Corporation that created the company’s classic arcade catalog and today’s Irem Software Engineering are connected by personnel, intellectual property, and corporate ancestry, but they are not simply the same legal corporation with a slightly different name. EIZO’s own history records that it acquired Irem Corporation in 1980, established Irem Software Engineering in April 1997, transferred the old company’s development division into the new corporation, and then sold the original Irem Corporation. Irem Software Engineering likewise describes itself as the company that inherited the development operations of its predecessor.
Understanding that distinction makes Irem’s history far more interesting. This is not just the story of a company that made R-Type. It is the story of an arcade manufacturer shaped by Japan’s rapidly expanding amusement industry, an unusually creative development culture, a corporate shutdown that scattered talented designers across the Japanese game business, and a name that survived even when the corporation behind it changed.
From IPM to Irem
The earliest years of Irem are also the hardest part of the story to reconstruct cleanly.
Retrospective histories generally trace the company back to IPM Co., Ltd., established in 1974 by Kenzo Tsujimoto, the businessman who would later become closely associated with the creation of Capcom. The surviving historical record becomes much firmer once the company was operating under the Irem name, however, and some of the colorful explanations repeated online about exactly what IPM originally represented, why the company changed its name, and what the letters IREM were initially supposed to mean are difficult to anchor to contemporary documentation.
That makes a little caution worthwhile. Rather than treating every later anecdote as settled corporate history, the safest chronology begins with the fact that Tsujimoto was involved with Irem during its early game-development period. Designer Takashi Nishiyama later recalled entering the industry at Irem when Tsujimoto was running the company. Nishiyama remembered joining around the end of the Space Invaders boom, when Irem was searching aggressively for its next successful game. His first design work included UniWar S, followed by a project that would become much more important: Moon Patrol.
Another company was already becoming central to Irem’s future.
Nanao Corporation, known today as EIZO, had its own roots in electronics manufacturing. EIZO’s official corporate history records that the company entered the development, production, and sale of tabletop gaming monitors in April 1978. In February 1980 it acquired Irem Corporation. The relationship meant Irem was no longer simply an independent game operation. It had become part of a larger electronics group with manufacturing knowledge and hardware resources.
That relationship would later have a direct effect on the games Irem could build.
Moon Patrol Carries Irem Overseas
The first Irem game to establish a major international identity was Moon Patrol.
The concept was immediately understandable. The player controlled a lunar vehicle racing across the surface of the moon, jumping craters and rocks while firing at hazards on the ground and enemies in the sky. The scrolling landscape created the illusion of a world extending beyond the immediate screen, while different layers of mountains and scenery moved at different speeds behind the rover.
What makes Moon Patrol especially useful to historians is the strength of its contemporary paper trail.
In July 1982, the American amusement trade magazine Cash Box reported that Williams Electronics and Irem Corporation had reached an agreement allowing Williams to manufacture Moon Patrol. The accompanying photograph showed Williams president Michael Stroll shaking hands with Irem president Kenzo Tsujimoto. Williams described its early testing of the game as showing strong player appeal.
The relationship quickly became more substantial than a casual distribution agreement. In August, Williams published a legal notice stating that it had acquired proprietary rights by assignment from Irem Corporation to manufacture and sell Moon Patrol worldwide outside Japan. The notice also warned potential imitators that Williams intended to protect those rights against unauthorized copies.
For Irem, the arrangement demonstrated a model that would become important throughout the first half of the 1980s. The company could create games in Japan, then rely on established amusement manufacturers and distributors to place those games into overseas arcades.
Players in Chicago, London, or another distant market might encounter a cabinet carrying the name of a local distributor, but the software at its heart had begun inside Irem.
Moon Patrol therefore represented more than one successful arcade game. It showed that Irem could create something capable of traveling internationally.
Licensing the Irem Arcade
The company continued using international licensing as its catalog expanded.
10-Yard Fight, released in Japan at the end of 1983, provides one of the clearest examples. Rather than attempting to establish a massive Irem-operated distribution network in every foreign territory, the company partnered with firms that already understood their regional amusement businesses.
In February 1984, Game Machine reported that Irem had licensed 10-Yard Fight to three overseas firms. Taito America received manufacturing and selling rights for North, South, and Latin America, while ADP-Automaten handled West Germany and Electrocoin Automatics received England and Ireland. Irem director Mamoru Shigeta explained that the arrangements would be fulfilled through the supply of printed circuit boards.
That business strategy meant an Irem game could spread far beyond the reach of the company’s own offices.
It also helped prepare Irem for an industry that was beginning to extend outside the arcade.
10-Yard Fight eventually became a Famicom and Nintendo Entertainment System title, placing the Irem name inside living rooms rather than only game centers. The transition was significant. The company that had established itself through coin-operated hardware was beginning to operate in an entertainment business where the home console would soon become impossible to ignore.
Still, the arcade remained central to Irem’s identity.
Its next major action game would show why.
Kung-Fu Master and a New Kind of Action Game
In Japan, the game was known as Spartan X. Overseas, many players encountered it as Kung-Fu Master.
The premise looked simple. A martial artist moved horizontally through floors filled with attackers, fighting toward increasingly dangerous opponents. Yet the structure was unusually important for the mid-1980s. Rather than placing opponents inside a fixed arena, the game forced the player continually forward through waves of enemies, giving hand-to-hand combat the kind of scrolling progression already familiar from shooters and action games.
Takashi Nishiyama was closely associated with the project before later moving through Capcom and eventually SNK. His path alone demonstrates how ideas and designers circulated between the companies that shaped Japanese arcade history.
Irem again pushed the game internationally through licensing. In February 1985, Game Machine reported that Irem Corporation, then under president Tetsu Takashima, had licensed Kung-Fu Master to Data East for North America, Electrocoin for Britain and Ireland, and NSM/Löwen for Germany and France, with additional agreements covering other territories.
The importance of the game went beyond its commercial distribution. Its forward-moving martial-arts structure belongs near the beginning of the history that eventually produced the scrolling beat ’em up. Later games would expand the idea with larger casts, more elaborate moves, simultaneous players, weapons, and increasingly complicated environments, but Irem had demonstrated how satisfying it could be simply to walk into a crowd and fight through it.
By the middle of the decade, the company had shown that it could succeed with science fiction, sports, and martial arts.
What it had not yet produced was the game that would become inseparable from its name.
The Development Culture Inside Irem
Part of what made Irem different becomes visible through interviews with the people who actually worked there.
A 1989 Gamest feature brought together several Irem developers, including development chief Tetsuo Nakano, planning chief Kozo Okada, Michiru Kawai, Kanae Saeda, and composer and designer Masato Ishizaki. Their discussion reveals a studio culture built around unusually elaborate preparation.
Saeda showed the interviewer the planning binder for R-Type. It was, she said, about as thick as a telephone book. Ishizaki explained that the purpose of such documents was to carry an idea from someone’s imagination into software without losing the details that made it interesting. Kawai noted that the documentation also helped separate programming and design teams communicate when problems appeared.
That painstaking preparation did not mean Irem wanted safe games.
Nakano argued that simply imitating whatever game was currently popular was a good way to be behind the industry by the time development finished. Ishizaki similarly recalled that Irem planners tried to begin with their own ideas rather than merely copying games they admired.
President Yoshiyuki Takashima described management in similar terms. He said Irem did not simply order developers to make a particular kind of game. The company gave teams room to pursue their ideas, then refined those ideas through planning meetings and commercial evaluation. His philosophy was that specialists should be placed where they were strongest and allowed to work.
It is tempting to look backward at Irem’s famously difficult arcade games and imagine a studio determined to punish players. The interviews present something more complicated. The developers certainly cared about challenge, but they also cared intensely about mechanical identity, visual presentation, and giving each game a recognizable selling point.
That culture reached its most famous expression with R-Type.
Building R-Type
The development of R-Type began with hardware.
Masato Ishizaki later remembered that Irem’s parent company Nanao had designed new arcade hardware and wanted a game that could show what it was capable of doing. The young development team began considering a shooter that could take advantage of the system. Ishizaki estimated that the average age of the team was only around twenty-three or twenty-four.
The original development team described the same beginning in a 1987 interview. Team leader Kinte recalled that the new 16-bit hardware could place many sprites on screen and offered enough processing power that a shooting game seemed like a natural fit.
The designers were well aware of Konami’s Gradius. Creating another horizontal shooter meant comparisons were inevitable, so the team searched for mechanics that would give its game a separate identity.
The answer became the Force.
The detachable orb could be attached to the front or back of the R-9, launched into enemies, used as a shield, or positioned away from the ship to fire from another part of the screen. The player was effectively controlling both a spacecraft and a movable weapon system.
The developers later joked that one early inspiration for the Force came from the image of a dung beetle pushing a ball. Whatever the unlikely origin, the mechanic solved a serious design problem. R-Type no longer needed to compete with other shooters only through more enemies or faster weapons. It asked players to think about where their firepower physically occupied the screen.
The team experimented constantly. Reflecting lasers were added because standard multi-directional shots seemed too ordinary. Stage concepts were developed in different orders and then arranged according to difficulty. The enormous battleship of the third stage demonstrated the new hardware’s ability to make scale itself part of the encounter.
The game also developed a visual identity considerably darker than many contemporary shooters.
In another 1987 interview concerning Irem’s experimental Battle Bird, developers explained that the company placed unusual importance on graphics and presentation. They specifically pointed toward the enormous battleship, grotesque creatures, and visual effects of R-Type as examples of what Irem wanted players to notice.
When the finished game reached arcades in 1987, Irem promoted it heavily. Game Machine advertisements presented the Bydo Empire as a place of hatred, violence, and unnatural creatures, while the screen images emphasized the huge sprites and biological machinery that made the game immediately recognizable.
Within Irem, there was little doubt which game had become the company’s defining success. When Gamest asked president Yoshiyuki Takashima in 1989 for the biggest hit of his first years as president, he answered R-Type, particularly in terms of sales volume.
Irem After R-Type
Success did not cause Irem to abandon the development habits that had produced R-Type.
Instead, the late 1980s became one of the most creative periods in the company’s history.
Ninja Spirit combined rapid movement with selectable weapons and dense enemy patterns. Image Fight took Irem back into shooting games but changed the perspective to vertical scrolling. Developers later explained that one of Image Fight’s central ideas was allowing the player to alter ship speed freely, another attempt to make movement itself part of the game’s identity.
Irem’s advertising made a direct connection between the new game and its earlier success. A 1988 Game Machine advertisement described Image Fight as a work from the staff behind R-Type, while once again carrying the company’s “Innovations in Recreational Electronic Media” slogan.
The company’s hardware relationship with Nanao remained important as well. Irem developers described themselves in 1987 as part of the Nanao Group and explained that the arrangement provided access to hardware-production facilities. They identified Irem, Tamtex, and Nanao itself as group companies involved with game planning and development.
This helps explain why Irem games from the period can feel so technically deliberate. Hardware and software were not always separate worlds. The company existed inside a corporate group capable of thinking about monitors, circuit boards, display technology, and game design as parts of the same amusement business.
By 1989, Irem’s president was still telling Gamest that arcade development remained the company’s priority, even while Famicom and computer software became increasingly important.
The balance would not last forever.
From the Arcade to the Home
Irem’s home-console catalog carried the company into a much larger consumer market.
Games including 10-Yard Fight, Spelunker, Kung-Fu Master, R-Type, and later titles associated with Irem or its related development operations reached consoles and computers in multiple regions. Some were direct arcade conversions. Others increasingly reflected a world in which development no longer had to begin with the assumptions of a coin-operated cabinet.
Yet Irem’s arcade DNA remained visible.
Its designers had learned to communicate ideas quickly. A player putting money into a machine had little patience for an hour-long introduction. The game had to explain itself through movement, enemies, sound, graphics, and immediate response.
That philosophy survived even as the company experimented with different formats.
At the same time, parts of Irem’s staff were becoming historically important for reasons that extended beyond Irem itself.
Developers connected to the company would eventually appear at Nazca, SNK, Granzella, and elsewhere. The visual techniques and mechanical instincts refined inside Irem did not disappear whenever an employee changed jobs. They moved through the industry with the people who had learned them.
That process accelerated dramatically in the 1990s.
1994 and the End of the Original Game Operation
By the early 1990s, the arcade business was changing rapidly.
Three-dimensional graphics were beginning to reshape expectations. Home consoles were becoming more powerful. Fighting games were dominating many arcades. Producing the intricate two-dimensional action games for which Irem was known no longer guaranteed the same position in the market.
Irem was still producing striking games. In the Hunt, Undercover Cops, and other late-period titles demonstrated that its artists and designers had lost little of their ability to fill a screen with detailed animation.
But the corporation was approaching a break.
The March 1994 issue of American coin-operated trade publication Play Meter reported that Irem was shutting down its arcade division. Later recollections from people who worked there describe the withdrawal more broadly as Irem leaving game production for a period.
Kazuma Kujo, who became one of the most important creators associated with the later Irem name, recalled that he left when the company withdrew from the game business in 1994. He would eventually return after the development operation was rebuilt several years later.
The shutdown had consequences far beyond the disappearance of one logo from new arcade cabinets.
Employees scattered.
Some former Irem talent fed into Nazca Corporation, the studio that created Metal Slug for SNK. Later interviews with former Irem developers repeatedly connect the detailed animation, machinery, explosions, and military worlds of late Irem games with the work that appeared in Nazca’s games afterward. Modern oral histories have made that personnel connection increasingly visible.
The end of Irem’s original arcade era therefore did not end the influence of its developers.
It dispersed it.
Irem Software Engineering Begins
Three years after the shutdown, the name returned in a new corporate form.
This is where the distinction between the old and new Irem becomes essential.
EIZO’s official history states that it established Irem Software Engineering Corporation in April 1997. In June, it transferred Irem Corporation’s development division to the new company and sold Irem Corporation. Irem Software Engineering’s own company history gives its establishment date as April 15, 1997 and says that it inherited the development-room operations of Irem Corporation that year.
The current company’s presidential message is equally explicit. Irem Software Engineering began in 1997 through 100 percent investment by EIZO, then known as Nanao, and succeeded the development operations of the predecessor Irem Corporation.
So the historical connection is genuine, but the corporate continuity must be described carefully.
The original Irem had ended its game-development period. EIZO then built a new corporation around the inherited development operation.
For players, the distinction was much less visible.
The Irem name was back.
So was R-Type.
R-Type Delta and the Second Irem Era
The revived Irem entered a video game industry that looked radically different from the arcade world of 1982.
Sony’s PlayStation had helped make polygonal graphics mainstream. Large three-dimensional environments were becoming increasingly common. The arcade was no longer the unquestioned technological center of the medium.
Yet Irem found a way to carry its old design identity into the new hardware generation.
R-Types arrived for PlayStation in 1998, followed later that year by R-Type Delta. Irem’s own product archive records R-Type Delta as a November 19, 1998 release.
The significance of Delta was not simply that R-Type had returned. It demonstrated that the series could use three-dimensional graphics without abandoning the carefully controlled side-scrolling play that defined it.
The new company also became more willing to move beyond shooters.
Kazuma Kujo, who had first entered Irem wanting to create role-playing games only to be told that RPGs were not what Irem specialized in, eventually became one of the central figures in this more experimental period.
That shift produced one of the company’s most distinctive games.
Disaster Report and an Irem Beyond Shooters
Zettai Zetsumei Toshi, released internationally as Disaster Report, asked players to survive a collapsing city after a natural disaster.
There were enemies, but they were not alien fleets or armies. The environment itself was dangerous. Buildings failed, streets became impassable, water mattered, and ordinary movement through the city became a survival problem.
Kujo explained in a 2002 interview that he was attracted partly by how few games treated disasters as their central subject. The team experimented with fatigue, eating, sleeping, and thirst before reducing the survival systems to mechanics that could support the pace of the game.
The project showed how far the Irem name had traveled.
The company remembered for Moon Patrol, and R-Type was now creating survival adventures, pachinko software, unusual action games, and titles such as Steambot Chronicles. Its old arcade instinct for creating a strong mechanical idea remained, but that idea no longer had to involve spaceships and bullets.
Even R-Type itself continued evolving.
When R-Type Final arrived on PlayStation 2, Kujo and the development team spoke openly about the difficulty of producing a traditional shooting game in a market where the genre was no longer mainstream. Yet they also believed the series’ Force system, wave cannon, strange creatures, and distinctive level design still gave it an identity worth preserving.
Once again, however, the company was approaching a turning point.
2011 and Another Generation Leaves Irem
The Great East Japan Earthquake of March 2011 intersected with an already difficult period for Irem’s consumer-game operation.
The company cancelled Disaster Report 4, a particularly painful decision given the game’s subject matter. Kujo later explained that development had already fallen behind schedule and that after the real earthquake there was no responsible way to determine whether the game could be delayed for three months, six months, or some indefinite period.
Other projects were cancelled as well.
Kujo and several former Irem colleagues established Granzella in April 2011. Granzella’s own history confirms its founding that month, while an early company diary records former Irem staff reflecting on their departure and the creation of the new studio.
The pattern resembled the 1990s in an almost uncanny way.
Once again, Irem was changing direction. Once again, developers who had learned their craft inside the company left together. Once again, the creative lineage survived somewhere else.
Granzella eventually obtained the rights to the Disaster Report series and returned to it. The new studio also became closely associated with the continuation of R-Type, meaning that part of Irem’s creative heritage migrated outward even though Irem Software Engineering itself continued operating.
The current Irem Software Engineering remains an active company. Its official corporate description lists development of visual software for pachinko and pachislot machines, consumer games, and smartphone applications among its business activities.
The company is therefore not merely a vanished arcade brand.
But the Irem remembered by many players belongs especially to the extraordinary run of games created between the early 1980s and the 1990s.
Why Irem Matters
Irem never became as universally recognizable as Nintendo, Sega, Capcom, or Namco.
Its historical importance is easier to see by following the games.
Moon Patrol demonstrated the company’s ability to create an arcade game that could cross international borders through a major American manufacturer. 10-Yard Fight showed how Irem could translate an unfamiliar sport into an immediately understandable arcade format and later move that design into the home. Kung-Fu Master helped establish the idea of fighting continuously through a scrolling action environment.
Then came R-Type.
Its Force system gave the player a weapon that was also a shield, a projectile, and a second firing position. Its enormous sprites made new arcade hardware feel genuinely new. Its artists created a world of machinery, flesh, aliens, and industrial landscapes that looked unlike most competing shooters. Its developers constructed stages that had to be learned almost as carefully as they had to be survived.
The company’s influence can also be measured through people.
Takashi Nishiyama moved through companies that would produce Street Fighter and major SNK fighting games. Former Irem developers helped create Nazca and Metal Slug. Kazuma Kujo carried the later Irem development philosophy into Granzella. The disappearance or restructuring of Irem repeatedly became the beginning of another chapter somewhere else in Japanese game history.
Perhaps that is why the company remains difficult to summarize.
Irem was an arcade company, but it became a console developer. It was known for shooters, but it created football games, martial-arts games, survival adventures, and strange experiments. The original corporation withdrew from game development, but a new Irem inherited its development operation. Developers left, formed other companies, and carried parts of Irem with them.
The logo changed. The corporation changed. The industry changed.
The ideas kept moving.
And nearly forty years after the R-9 first flew toward the Bydo Empire, the name Irem still brings to mind the same qualities its developers talked about in 1989: games built around a strong idea, obsessive planning, technical craftsmanship, and a refusal to disappear quietly into whatever everyone else was already making.
Sources & Further Reading
EIZO Corporation. “Company History.” Accessed October 14, 2026. https://www.eizoglobal.com/company/history/
Irem Software Engineering Inc. “Company Profile / History.” Accessed October 14, 2026. https://www.irem.co.jp/company/outline.html
Irem Software Engineering Inc. “Message from the President.” Accessed October 14, 2026. https://www.irem.co.jp/company/message.html
Irem Software Engineering Inc. “Product Information.” Accessed October 14, 2026. https://www.irem.co.jp/product/
Irem Software Engineering Inc. “Game and App Production Achievements.” Accessed October 14, 2026. https://www.irem.co.jp/results02/index.html
Amusement Press. Game Machine. Complete archive, 1974–1996. Accessed October 14, 2026. https://onitama.tv/gamemachine/archive.html
Amusement Press. “Irem Licenses Manufacturing Rights for Moon Patrol to Williams Electronics.” Game Machine, August 1, 1982. https://onitama.tv/gamemachine/pdf/19820801p.pdf
Irem Corporation. Advertisement for Moon Patrol. Game Machine, September 1, 1982. https://onitama.tv/gamemachine/pdf/19820901p.pdf
Williams Electronics. “Moon Patrol” Legal Notice. Cash Box, August 21, 1982. https://www.worldradiohistory.com/Archive-All-Music/Cash-Box/80s/1982/CB-1982-08-21.pdf
“Ali-Boo-Chu Licensed from Irem of Osaka, Japan.” Cash Box, June 12, 1982. https://www.worldradiohistory.com/Archive-All-Music/Cash-Box/80s/1982/CB-1982-06-12.pdf
Amusement Press. “10-Yard Fight.” Game Machine, January 1, 1984. https://onitama.tv/gamemachine/pdf/19840101p.pdf
Amusement Press. “Irem Licenses Its ‘10 Yards Fight’ to Three Overseas Firms.” Game Machine, February 15, 1984. https://onitama.tv/gamemachine/pdf/19840215p.pdf
Irem Corporation. Advertisement for 10-Yard Fight. Game Machine, March 1, 1984. https://onitama.tv/gamemachine/pdf/19840301p.pdf
Amusement Press. “Irem Licenses Kung Fu Master.” Game Machine, February 15, 1985. https://onitama.tv/gamemachine/pdf/19850215p.pdf
Irem Corporation. Advertisement for R-Type. Game Machine, September 1, 1987. https://onitama.tv/gamemachine/pdf/19870901p.pdf
Irem Corporation. Advertisement for Image Fight. Game Machine, October 15, 1988. https://onitama.tv/gamemachine/pdf/19881015p.pdf
Amusement Press. “Best Hit Games.” Game Machine, April 1, 1989. https://onitama.tv/gamemachine/pdf/19890401p.pdf
“Irem Arcade Games: 1989 Developer Interview.” Originally published in Gamest, 1989. Translated by Shmuplations. Accessed October 14, 2026. https://shmuplations.com/irem/
“R-Type: 1987 Developer Interview.” Shmuplations. Originally published 1987. Accessed October 14, 2026. https://shmuplations.com/rtype1/
“Battle Bird: 1987 Developer Interview.” Shmuplations. Originally published 1987. Accessed October 14, 2026. https://shmuplations.com/battlebird/
Ishizaki, Masato. “R-Type: 2014 Composer Interview.” Interview originally published in Shooting Gameside, no. 9. Translated by Shmuplations. https://shmuplations.com/rtypesound/
Ishida, Masahiko. “R-Type: Masahiko Ishida Interview.” Interview originally published in Shooting Gameside, no. 9, 2014. Translated by Shmuplations. https://shmuplations.com/rtypeishida/
“R-Type Delta: 1998 Developer Interview.” Shmuplations. Originally published 1998. https://shmuplations.com/rtypedelta/
Kujo, Kazuma, Koichi Kita, and Hiroaki Yamada. “R-Type Final: 2003 Developer Interview.” Originally published in R-Type Final Official Master Guide, 2003. Translated by Shmuplations. https://shmuplations.com/rtypefinal/
Kujo, Kazuma. “Disaster Report: 2002 Developer Interview.” Shmuplations. Originally published 2002. https://shmuplations.com/zettaizetsumeitoshi/
GameSpot. “R-Type Final Q&A.” January 22, 2004. https://www.gamespot.com/articles/r-type-final-qanda/1100-6086851/
Retro Gamer. “The Making of R-Type.” Issue 51. https://electronicsandbooks.com/edt/manual/Magazine/R/Retro%20Gamer%20UK/51.pdf
Play Meter. “Irem Shuts Down Arcade Division.” March 1994. International Arcade Museum archive. https://library.arcade-museum.com/magazine/play-meter
Play Meter. Buyer’s Guide. September 1992, 94. https://elibrary.arcade-museum.com/Play-Meter/1992-September/94
Play Meter. “Equipment Poll.” August 1993. https://elibrary.arcade-museum.com/magazines/pm/PlayMeter-1993-08/PlayMeter-1993-08-009.pdf
Play Meter. “Equipment Poll.” May 1994. https://elibrary.arcade-museum.com/magazines/pm/PlayMeter-1994-05/PlayMeter-1994-05-008.pdf
Matsumoto, Shigekazu, and Hiroyoshi Hashimoto. “Dice Displaying Apparatus for a Computer Game Machine.” U.S. Patent 5,263,715, filed October 5, 1992, and issued November 23, 1993. Assignee: Irem Corporation. https://patents.google.com/patent/US5263715A/en
Justia Patents. “Patents Assigned to Irem Corporation.” Accessed October 14, 2026. https://patents.justia.com/assignee/irem-corporation
Nishiyama, Takashi. “Takashi Nishiyama Interview.” Cultura Neo Geo. Accessed October 14, 2026. https://www.culturaneogeo.com/imagenes/entrevistas/streeteng.htm
Famitsu. “Interview with Former Irem Programmer Shinichi Hamada.” 2020. https://www.famitsu.com/news/202008/03202933.html
Szczepaniak, John. “We Sat Down With Legendary Irem Devs to Talk Game Design, Pixel Art and Sekaikan.” Time Extension, January 2024. https://www.timeextension.com/news/2024/01/we-sat-down-with-legendary-irem-devs-to-talk-game-design-pixel-art-and-sekaikan
Time Extension. “The Making of In the Hunt: Metal Slug’s Underwater Forerunner.” Accessed October 14, 2026. https://www.timeextension.com/features/the-making-of-in-the-hunt-metal-slugs-underwater-forerunner
Time Extension. “The Making of Metal Slug: ‘I Never Thought That It Would Have Sequels.’” Accessed October 14, 2026. https://www.timeextension.com/features/the-making-of-metal-slug-i-never-thought-that-it-would-have-sequels
Szczepaniak, John. The Untold History of Japanese Game Developers. Vol. 2. n.p.: SMG Szczepaniak, 2015. https://www.hardcoregaming101.net/books/the-untold-history-of-japanese-game-developers-volume-2/
Smith, Alexander. They Create Worlds: The Story of the People and Companies That Shaped the Video Game Industry. Vol. 1, 1971–1982. Boca Raton, FL: CRC Press, 2019. https://www.routledge.com/They-Create-Worlds-The-Story-of-the-People-and-Companies-That-Shaped-t/Smith/p/book/9781138389908
Kent, Steven L. The Ultimate History of Video Games. New York: Three Rivers Press, 2001. https://www.penguinrandomhouse.com/books/91835/the-ultimate-history-of-video-games-volume-1-by-steven-l-kent/ebook/
Herman, Leonard. Phoenix IV: The History of the Videogame Industry. Rolenta Press. https://thegamescholar.com/about1/
International Arcade Museum. “Irem.” Museum of the Game. Accessed October 14, 2026. https://www.arcade-museum.com/company/irem
MobyGames. “Irem Software Engineering, Inc.” Accessed October 14, 2026. https://www.mobygames.com/company/2163/irem-software-engineering-inc/