Sneaky pinball makers' tricks

Northwestern economics professor Jeff Ely has a fun post on his blog about the economics of pinball:
Img 3732In 1986, Williams High Speed changed the economics of pinball forever.  Pinball developers began to see how they could take advantage of programmable software to monitor, incentivize, and ultimately exploit the players.  They had two instruments at their disposal:  the score required for a free game, and the match probability.  All pinball machines offer a replay to a player who beats some specified score.  Pre-1986, the replay score was hard wired into the game unless the operator manually re-programmed the software.  High Speed changed all that.  It was pre-loaded with an algorithm that adjusted the replay score according to the distribution of scores on the specified machine over a specific time interval. ...

The other tool is the match probability: you win a free game if the last two digits of your score match an apparently random draw.  While adjustments to the high-score threshold is textbook price theory, the adjustments to the match probability is pure behavioral economics.  Let’s clear this up right away. No, the match probability is not uniform and yes, it is strategically manipulated depending on who is playing and when.  For example, if the machine has been idle for more than three minutes, the match probability is boosted upward.  You will never match if you won a free game by high score.  And it gets more complicated than that.  Any time there are two or more players and they finish a game with no credits left, one player (but only one) is very likely to match.  Empirically, the other players will more often than not put in another quarter to play again.

The Economics of Pinball

(Above: my photo of the Visible Pinball Machine built by Michael Schiess of the Lucky JuJu Pinball Arcade)



  1. I’m convinced those things have magnets that suck the ball down the exit chute. (Or is it just my pinball playing that sucks?)

  2. OK. So, question time. Do we admire their sneakiness and cunning or curse them for being greedy pakhtash like the movie and record industries?

  3. @jfrancis – There is no need for magnetic interference. The geometry of the table can be designed to give the ball a higher probability of going down the middle just out of reach of the flippers. I would guess mastering a particular pinball machine would involve avoiding those targets that tend to direct your ball that way.

  4. “Empirically, the other players will more often than not put in another quarter to play again”

    “another quarter” should be “more quarters”

    It was probably in the late seventies/early eighties when I last played a pinball machine where only a single quarter would let me play (or play again).

    1. I find single quarter machines all the time – mostly on the road playing dives, so their condition is often questionable but the last one I found was a playboy machine in a Salt Lake City hotel game area that actually showed nipples when the magazine bonus was triggered (the mini magazine in the machine opened to show the centerfold)

  5. I’ve always suspected the “match” thing was not fully random.

    jfrancis, I don’t think they magnetically suck the ball down the chute… but some machines can adjust things like paddle strength and response time. And of course, the operator can adjust the table slope by raising or lowering front vs. rear legs, and things like tilt sensitivity etc.

  6. This is GOLDEN, except for the fact that the match percentage stuff is bullshit. I own a Williams Demolition Man, and it MOST ASSUREDLY DOES award match even after beating the high score for a free game.

    I suppose it’s possible that the 1986 reality continued to change over the years, though…

  7. I’ve always known the replay value to adjust, but never knew there were formulas for the match. Makes sense, the more I think about it (and that two player, one match thing is just downright sneaky).

    There’s an annual Pinball Expo that runs through Chicago here, and the last one was a little over a month ago in October. I’ve attended two of the events, and took a lot of photos/videos while I was there (in between small binges of Black Knight 2000 and Bride of Pin Bot).

    Note: these are links to my site, but I’m hoping this counts as staying on-topic:
    Pinball Expo 2007 and 2009

  8. I’ve gotten matches after Special, and I’ve also received the BONUS JACKPOT MATCH of a match of all 4 players. (THWACK THWACK THWACK TWHACK) That’s ridiculously awesome, and it’s only happened to me once or twice in all my years of playing pinball. But I know that match probability is definitely maintained to a % of total play, and it’s something you can adjust in the owner controls as well.

    And magnets in the table is pretty much a non-issue, with the exception of The Addams Family, but that’s pretty well made pretty apparent as part of the game. (I still hate Seance.)
    Other games utilize magnets but for different and obvious ball-stopping effect- from the factory, the tables aren’t equipped for larceny.

    Any super weird caroms can usually be explained by spin of the ball- the ball can pick up amazing amounts of spin by rolling by rubber at high speeds, but the relatively low friction of a nicely waxed table keeps the ball skidding across the surface of the table. (If a table is maintained well, the ball doesn’t roll so much as it slides.) Once the “charged” ball hits another surface (post, target, rubber, etc) the direction of the ball can take some amazingly odd caroms.

  9. this reminds me of my arcade hang out youth-knew this stoner guy who played this video game called ‘Pengo’. It was like Donkey Kong, only with a penguin sliding on ice-you had to use the slide feature, of course, and it was tricky.

    He used to ‘wrap’ the game on a single quarter-and not too many people played the game. The owners finally got annoyed, and thus began a slow, months long battle. They kept resetting the machine, I don’t know the specifics, but it upped the skill needed, and made it harder to play. Stoner guy would come in, stoned, and play the increasingly hard levels. And wrap it each time-sometimes several times. Wrapping, for those not in the know, is when you sail past the highest score the machine has to offer, and it resets, back to beginner levels.

    he’d play for hours. finally, the owners set it on the highest setting they could, and he still wrapped it, many times. Stoned. Plus, no one else could play the game. he’d effectively made it his very own game.

    In digust, the owners surrendered, and set the machine back to a more reasonable level. stoner guy happily continued on, whiling away entire afternoons, playing Pengo.

  10. Those sneaky pinball designers! It only stands to reason that they’d do slot-machine tricks on a pinball.

    My 1976 Gottlieb Ship Ahoy game doesn’t have that problem. But it doesn’t have a match unit at all, and it gives only extra balls for high score instead of free games.

  11. I own four pinball machines, all from the 1980s. The late-80s machines have an adjustable match percentage that can be set anywhere from 1 percent to 50 percent; the default is 7 percent. As far as single-quarter play goes, the last Williams machine that came 1 play per quarter by default was Earthshaker in 1989. Williams tried an experiment with Black Knight 2000, also in 1989, of requiring 2 quarters per game but giving 5 balls per game (machines by default went from 5 balls/game to 3 balls/game in the early 1980s), but that didn’t go over very well, so subsequent machines came by default giving 1 credit for $0.50, 2 for $0.75, and 3 for $1. In fact, machines in the early 1990s were shipped without even the option to set them for 1 play for $0.25– some operators ended up crosswiring the coinslots so that 1 quarter in one slot would trigger both, so that they could have $0.25/play.

  12. None of this info seems particularly sneaky or tricky.

    In the case of replay adjustment, the replay score is dynamic and adjusts according to skill/record. It’s not like anything is being removed from the game or experience.

    In the case of matches, the feature is – as well – not removed from the game. It just adjusts accordingly. And even if there was nothing in the algorithm that upped the match percentage during two person games (so that one person would obtain the match, and the other person would feel compelled to put in new quarters), the chance that 1 of 2 would match would still be greater than if it was a one person game. Operators have the power to set match percentages. If it was a stable 10%, you’d see way more matches on four person games. Big whoop!

    Operators also have the power to – on many newer machines – set it so that if you put in a quarter (just 1) within ten seconds of your game ending, you’ll get another credit (a 2 quarter value). Should that be considered sneaky or tricky, too?

    Replays and matches to be nice bonus features. This isn’t very sneaky.

  13. I have a 1960 Gottlieb “Wagon Train,” and even it comes with instructions on how to tweak it to your desired level of difficulty. Obviously not as advanced as this kind of tweaking, though.

    Oh, and “Pengo” was an awesome game.

  14. Hey, guy who posted about the pinball convention (avoision)! I go to expo with my parents every year, my father has a booth and speaks sometimes in the seminars (he’s a collector). He brought the game he made himself with him this year, it was a gangster-themed pin, dunno if you noticed it. This clear pinball was pretty badass, to stay on-topic.

  15. So… doesn’t this mean you can actually exploit the 2-player – probably match algorithm?

    If bored (or due to economics of some machines coinslots) I will occasionally just play doubles against myself. It doesn’t really affect my gameplay that much.

    So if the match % is bumped up anything over 20% when the machine sees I’m tag-teaming … I’ve got a better-than average chance of getting at least one free game out of it?

    I always suspected a machine should start fudging the numbers when it detected credits stacked up … but I remember being surprised that it felt like the opposite was happening. I remember a local version of Medieval Madness seemed to never want to let me leave!

  16. On the topic of pinball, a new trailer was just released for the feature documentary “Special When Lit” Im pretty stoked about it! The pinball industry is dying but were hoping for a comeback, this movie may help.

  17. in my experience, the match or free game has never granted me anything. ever. I would play my game and move along. Had the game been more gracious and let me play a free game or two I would probably been more likely to add more quarters to the machine. I think there is a non-linear relationship here that the pinball makers don’t account for. A quick end game results in just that. Frustration. Move along. A prolonged game causes a sort of attachment between the player and the machine……

  18. This is simply great game design and beautifully simple. Designers of modern video game should read this and meditate on it.

  19. I worked on the older electro-mechanical pinball machines and they did much the same thing using what they called a “reflex unit”. It kept a “sum” of games won / games played and adjusted several functions of the machine to make it easier or harder to win. So if you were a pinball wizard, it would gradually tighten up until you couldn’t win. Then a string of losing games would cause the machine to loosen up. It was adjustable (plugs in terminal sockets) and operators used that adjustment to set the average playing time per coin.

  20. There’s more about “High Speed”–and about pinball design–from the Williams designers in the documentary “TILT: The Battle to Save Pinball.” (Plus 3 extra hours of designer interviews on the bonus disc.) Out on DVD, iTunes, and Netflix:

    If you liked this article, you’ll like the film.

  21. Not True ! This guy really needs to get his facts straight.

    The percentage of times a Match drawing awards a free game is adjustable. The operator can set this number via the configurations of the game. The default is typically 7-10% of the time.

    It is totally possible to win a free game by achieving the replay score and still match to win an additional free game. I have done this many, many times. How long the game has sat idle, how many players played, whether they won a free game or what their score was has NOTHING to do with whether you win a match !

    Why disseminate incorrect information?

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