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Space Invaders Targets Coins
By Mark Fox, World Coin News
January 17, 2012

This article was originally printed in World Coin News.
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As the oft-quoted story goes, during the late 1970s Japan was hit with a coin shortage of 100-yen coins that, according to one account, crippled its primary means of travel, the subway. The shortage was so severe that the Japanese Mint was forced to double or quadruple 100-yen coin production, depending on the source one reads.

While coin shortages in modern times are fairly common and have been attributed to a variety of causes, this one has the distinction of being instigated by “space invaders” – the type from outer space, bent on the earth’s destruction!

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Happily, these were the coin-operated versions in the arcade video game of the same name, which required 100-yen coins to play. And yet, for many of those who witnessed the game’s release in 1978, the invasion was no less real. The reality of the 100-yen shortage, on the other hand, related by countless articles, books and several television documentaries, is an amazingly complex story that numismatists, until recently, may not have even heard of. For the first time, this article will attempt to explain what really happened and, at the same time, offer a thorough knowledge of the game and coins implicated in the plot.

Enter Space Invaders

Space Invaders was the brainchild of Toshihiro Nishikado, a Japanese game developer for the arcade game publisher Taito Corporation. Not only did Nishikado write the program, but he spent a year designing the actual hardware and tools for it. He later recalled in an October 2005 interview with Edge Magazine that, “the hardest part was the development of a microcomputer. Microcomputers were hardly used at that time in Japan, so we had to create one from scratch. I could almost say developing the microcomputer was harder than developing the game itself. These days, we have personal computers to rely on, but there was no programming environment back then. So I had to create everything by myself. I created a development device, wrote a part of the game that runs on it and then created more devices along the way.”

Early on, Nishikado tinkered with the idea of using airplanes, tanks and marching solders as enemy targets. The first two proved too technically challenging to animate convincingly, and Taito was firmly against shooting people or creating “the image of war,” the game developer told USA Today in a May 2009 talk. It was then he heard of a new movie that would soon be shown in Japan called Star Wars.

“I thought a space fad might be on the way,” Nishikado explained. “And decided to focus on aliens.”

For inspiration of what these “space invaders” would look like, he turned to the many-tentacled Martians described in H.G. Wells’ War of the Worlds.

Unlike what some have implied, certain aspects of Space Invaders, such as its sounds and even its title, were worked on by Taito developers other than Nishikado. But it was his pioneering efforts that created an arcade video game unlike anything seen up to that time.

The game play was based on Atari’s 1976 hit Breakout. In this game, a paddle controlled by the player at the bottom of the screen bounces a ball against rows of bricks at the top, each brick being destroyed when hit by the ball. In Space Invaders, the bricks are replaced by waves of menacing aliens marching towards Earth, while the paddle becomes a laser canon that the player fires at the invaders between several defense bunkers. The game ends if the space invaders reach Earth or if the aliens destroy all of the player’s laser canons.

Taito’s feelings were actually doubtful about the game’s success when it was released in June 1978. The year before saw the “Video Game Crash of 1977,” caused in large part by a glut of Pong arcade games and its imitators. But after a few months of doing poorly, Space Invaders began to show signs of life as the word spread. By October, when Americans were first invaded by Space Invaders – via the Midway division of Bally under license from Taito – it was a national sensation in Japan.

As Brian Ashcraft and Jean Snow in Arcade Mania: The Turbo-charged World of Japan’s Game Centers (2008), put it: “With Japan in the throes of Star Wars fever, Space Invaders was a no-brain arcade smash hit. When players went to arcades, all they wanted to do was shoot aliens in space. It was no accident that the first game centers were called ‘invader house’ in Japanese. They were wall-to-wall with upright and countertop Space Invaders coin-ops. In 1978, these one-room arcades popped up overnight in urban centers like Tokyo and Osaka, blasting out the game’s instantly recognizable ‘dun dun dun’ theme music.”

Everyone, it seemed, wanted a share of this lucrative market, from Japanese vegetable venders to U.S. funeral homes. It is probably not too strong to even suggest that Space Invaders saved the earthlings at Chuck E. Cheese and helped make them what they are today. Video game historians often credit this single, early shooter game for paving the way for an era that has become known as the Golden Age of Video Games.

Arcade Fuel

Other coins such as the 50-yen were popularly accepted by arcade machines during the early years of arcade video games, but all reports point to its double as being the coin needed to play Space Invaders. Like other Japanese coins after World War II, the 100-yen denomination went through several stages before arriving in its current form.

The first issue was introduced in 1957 and lasted only two years. It was struck with a reeded edge in an alloy of 60 percent silver, 30 percent copper and 10 percent zinc. Designed by Hiroo Miyazaki, it is known as the Phoenix type in honor of the mythological bird, with wings spread wide, that graces the coin’s obverse. According to the late Michael Cummings in the second edition of Japanese Modern Coinage (1978), the center of the reverse displays “a sunburst enveloped by a symmetrical cherry blossom design.” The designer is said to have modeled his work after the floral reverse found on British florins struck from 1954-1970.

An open design competition resulted in the attractive Rice Plant design that debuted in 1959. The reverse sports a large and clear “100” value mark in the center with horizontal lines to the right and left that were intended to help the blind separate this denomination from nickel 50-yen coins, which, for the first four years (1955-1958), were not holed. No 100-yen coins were struck for 1962.

At 22.6 mm in diameter and weighing 4.8 grams, the 100-yen was an obvious choice in 1964 for some of Japan’s first commemorative coins, being then the highest denomination struck for circulation. The occasion was the 1964 Olympics held in Tokyo. The coin’s obverse featured the five Olympic rings superimposed over the Olympic flame. Judging by their availability, many pieces were kept as souvenirs.

As was happening all across the world, soaring silver prices and rampant hoarding during the 1960s made silver coinage, even at 60 percent fine, unsustainable. The Japanese Mint responded by converting the 100-yen to copper-nickel in 1967, in the same ratio as enjoyed by the U.S. 5-cent piece and most other copper-nickel coinages: 75 percent copper, 25 percent nickel. But not before the Japanese denomination had one more makeover, attributed again to the work of Hiroo Miyazaki. The sheaf of rice on the reverse gave way to an appealing cluster of three cherry blossoms with foliage. Probably because unholed 50-yen coins were last minted almost a decade before, the parallel lines on the flipsides of their 100-yen siblings were removed. To compensate for this, the value mark was enlarged. Of the three different series of 100-yen coins issued, the last was undoubtedly the one used in bulk by insatiable Space Invaders players.

Of course, it wouldn’t be fair to move on without spilling some ink on dating modern Japanese coins. Thankfully, there is really nothing here to fret about, especially when Cherry Blossom 100-yen coins are concerned. On these, the emperor’s year of reign appears in Arabic numerals. From Dec. 25, 1926, to Jan. 7, 1989, the reigning emperor was Hirohito. The era that accompanied his reign was known as Sh?wa (“radiant” or “enlightened peace”). So a 100-yen coin minted in 1975 would bear the Arabic number “50” and be read as “Showa 50.” (In the view of the Japanese Mint, the date side of a Japanese coin is also the reverse.)

For the more ambitious who would like to comprehend dates composed of Japanese characters, they needn’t look any further than the extremely helpful guides provided by Lion Coins at, or the PDF file prepared by the Bank of Japan,

Figures That Don't Figure

Numerous video game histories have related the story of the 100-yen coin shortage against a backdrop of unprecedented demand to play an arcade game that would initiate a whole new generation of video games and forever leave its mark on the industry. Even the Guinness World Records Gamer’s Edition 2008 had a few relevant words to share: “It is difficult to determine the most successful arcade shooting game, as it’s hard to track the earnings of each individual cabinet. But Space Invaders must be a serious contender: shortly after the game was released in Japan, it is widely believed to have inspired a coin shortage, which required the supply of the 100-Yen coin to be increased.”

The claim that the Japanese Mint was compelled to strike two to four times the normal amount of 100-yen coins in response to the shortage sounds completely plausible, until one happens to browse through the mintage figures listed in the Krause Standard Catalog of World Coins 1901-2000:

Showa 42 (1967)      432,200,000
Showa 43 (1968)      471,000,000
Showa 44 (1969)      323,700,000
Showa 45 (1970)      237,100,000
Showa 46 (1971)      481,050,000
Showa 47 (1972)      468,950,000
Showa 48 (1973)      680,000,000
Showa 49 (1974)      660,000,000
Showa 50 (1975)      437,160,000
Showa 51 (1976)      322,840,000
Showa 52 (1977)      440,000,000
Showa 53 (1978)      292,000,000
Showa 54 (1979)      382,000,000
Showa 55 (1980)      588,000,000
Showa 56 (1981)      348,000,000
Showa 57 (1982)      110,000,000
Showa 58 (1983)      50,000,000
Showa 59 (1984)      41,850,000
Showa 60 (1985)      58,150,000

Certainly no doubling or quadrupling of mintages can be seen here for the period we are interested in. Note how consistently high they are throughout the 1970s and how the numbers plummet after 1982. Similar stories can be told of the 10- and 50-yen coin series as well.

Now Figure This …

So what are we to make of the mintage statistics? Was there a Japanese 100-yen coin shortage at all? The fact that Space Invaders eventually topped 300,000 arcade machines in Japan, plus 60,000 more in the U.S,, surely must have generated some impressive earnings for arcade owners. One popularly quoted and presumably reliable estimate, taken from Steve Bloom’s Video Invaders (1982), places the global figure at over 4 billion quarters, or $1 billion, as of mid-1981.

How many different currencies were figured in is unknown to this writer, but if we calculate (perhaps conservatively) that one-half of the total was contributed by Japan, plus an average exchange rate of about 215 yen to the dollar from 1978-1981, we are confronted with a staggering hoard of roughly 1.064 billion 100-yen coins. Compare that to the approximately 1.436 billion 100-yen coins minted during the first three and a half years of Space Invaders.

Since it would have been in Taito’s best interests to empty their arcade machines as fast as possible and cash in the revenue, it would be wrong to think that the economic impact of Space Invaders was akin to the Japanese Mint not minting 100-yen coins for roughly three years. Even so, no matter how one looks at it, there must have been a lot of coins tied up in the arcades at almost any given time.

When Eric Patterson for Play Magazine asked Toshihiro Nishikado in 2009 for a small, not often heard anecdote about Space Invaders, the game’s creator was thoughtful. “Let’s see. Perhaps the time when the tires on the car Taito used to collect coins from the arcades went flat from the weight.”

Chris Kohler, editor of GameLife, may have been the closest to the mark when he explained to this writer that his “understanding of [the shortage] was always that there had not been an increased production of coins, but that certain Tokyo newspapers had simply reported on spot shortages of coins.”

This is in agreement with the accounts of two numismatists who reported nothing out of the ordinary while either visiting or living in Japan during the height of the Space Invaders invasion.

In summary, the appetite of Space Invaders arcades for 100-yen coins may have been uncomfortably high after all, but not alarming enough for the Japanese Mint to fight back.

Hi-Ho Silver and Big Brother

Left unexplained are the fat mintage numbers for 1970s era 100-yen coins and the sharp decline in the subsequent decade. What happened here? It is not always easy to interpret the logic behind such numbers, but in the opinion of one American dealer of Japanese coins who has lived in Japan for over 40 years, the first phenomenon can be attributed to hungry silver speculators. In response to the hoarding of silver 100-yen coinage (which contained 0.0926 ounce of silver or a little more than a U.S. dime’s worth), the Japanese Mint steadily pumped circulation with silver-less coins for many years. The dealer points to one date in particular: “If you check the mintage figures again you’ll see that in 1980 the production jumped to 588,000,000 coins. This, I believe, was because of the large number of silver 100 yens being exported for their silver value. These coins could not be, and still can’t be, melted for their silver value in Japan!”

To grasp the second part of the puzzle, we need to understand that Japan had entered an economic decline during the 1980s, caused in part by trade tensions with countries that were hard put to compete with Japanese exports. Being under pressure by the United States and others, the Japanese government purposely tried to deflate the yen and encourage more imports and less exports. One way to achieve a stronger currency is to mint fewer coins. By comparing this period with the high inflationary export boom of the 1970s, we can also see why so many Japanese coins were minted in the ’70s, an additional reason for the strong 100-yen numbers.

Perhaps another explanation for the 100-yen dip can be linked to the rise of the hefty 500-yen coin in 1982. It replaced the 500-yen note and was minted, according to the Japanese Mint, “in response to a need for a higher value coin for use in vending machines.” This big and heavy copper-nickel brother of the 100-yen was struck in large numbers for the first several years, nicely offsetting the weak production figures for the lower denominations. Depending on exchange rates, the 500-yen possesses one of the highest face values of any coin in world circulation today, $6.45 as of this writing.

Video Game Hero?

For video game designer and industrialist Mark Cerny, the 100-yen was not a victim of arcade video games, but rather their savior. According to a February 2011 interview with Cerny by Kotaku blog editor Brian Crecente, this coin helped keep Japanese arcades afloat while American arcades eventually sank into oblivion from the dwindling purchasing power of the quarter.

Crecente writes: “It all came down to the quarter Cerny said. Arcade games had to squeeze enough money out of people to be worthwhile for arcade owners and game makers. But they also had to deliver enough play time to make it worth while for gamers to drop in their money.”

One idea that was pushed was multiple-player games, but in the end no real solution was found. The Susan B. Anthony dollar never caught on, and in any case, by the end of the 1980s, video game consoles and PC games had taken over the market and convinced most gamers to play within the comfort of home.

Ironically, Japanese arcades are still alive and well today, and depending on the location, machines can still be found that accept 100-yen per play, although many are much higher now. However, some reports seem to indicate that the survival of Japanese arcades had more to do with innovation rather than being monetized correctly. Some gamers have noted that high denomination coins were available in other countries during the 1980s, but were, nevertheless, unable to stop the arcades there from largely going the way of the dodo.

No matter how you look at it, the 100-yen coin is firmly intertwined with the lore of Space Invaders. To own this numismatic piece of arcade memorabilia, a collector will only need about $2 to own a BU example from the Golden Age of Video Games, or enough money for a U.S. Space Invaders fan of the period to try to save the world eight times.

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