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Does Mathematical Tuning Make Games Better?

Posted by Zonk on Wed Jan 24, 2007 02:32 PM
from the pi-over-rockets-equals-killing-spree dept.
simoniker writes "What do game designers need to know about statistics? Age Of Empires DS designer Tyler Sigman focuses on statistical topics that he believes should be understood by game designers, in a new article. His reasoning: 'In the game I just finished, we recorded data from play sessions and then set challenge levels in the game based upon the mean and standard deviation values from those recorded data. We set Medium difficulty to be equal to the mean values, Easy difficulty to be equal to the mean minus a certain amount of standard deviations, and then Hard difficulty equal to the mean plus a certain amount of standard deviations.' Would all games be better if they were tuned mathematically?"
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  • by AKAImBatman (238306) * <akaimbatman.gmail@com> on Wednesday January 24 2007, @02:38PM (#17741804) Homepage Journal
    "Tuning" makes games better. Period. End of story.

    Since tuning is all about improving the feel of the game to the humans who will interface with it, it all depends upon the creator for how he wishes to accomplish this. In this case, the creator was looking for sweet spots that he was able to find through mathematical manipulation of sampled data. In other cases, using math to tune the results might give the game a clinical feel; something that's generally bad for video games. (Unless you're playing Trauma Center. :-P)

    So the question is pretty much moot. Creating a good game is an art form, but even art can benefit from a few structural calculations. :)
    • That's architecture... the blending of form and spirit, with the cold hard numbers that make it possible. A painting can be done with ANYTHING, and still fulfill it's role. If a building looks the way you want, but you forgot to carry some threes, you're probably going to kill some people, and go to jail for neglicence.


      More games need that kind of accountability. :)

    • You are correct!

      Mathematical tuning is a good place to start, but basing everything off of it is NOT a good idea. You always need a base point, and what better base poitn to use then some cold numbers. However from there you need to test it out and see if the game is still FUN, and if it is not, what are the problems?

      I actualy have seen a few instances where developers knew the game was unbalanced (win/loss records always favored one team), however left it that way becasue the game was actualy more fun to
      • by lostboy2 (194153) on Wednesday January 24 2007, @03:36PM (#17742690)
        I'll hop on the agreement bandwagon. Mathematics alone does not make for a better game.

        Case in point: I once had a cribbage game where you could play against the computer and set different levels of difficulty. I quickly discovered that "Expert" level just meant that the computer got better hands more often -- it had nothing to do with the quality of the computer's strategy. After getting lousy hands several games in a row while the computer consistently drew hands like 4-5-5-6, I simply stopped playing. While "Expert" level was certainly harder, it was also not fun to play.

        So, while TFA has a point about statistics being important for game design, that's not much more profound than saying that vision is important for driving cars well.

    • It seems like the best way to go about tuning a game would be to employ a few mathematical methods and do the rest by hand. A mathematical model is only going to be as good as the data that you put into it. There's always going to be some margin of error. While statistical approaches could help developers tune a game quickly, there will still need to be manual adjustments.
    • well, there is quite a lot of math happening in our brains (and withing human behavior) at any given time, so this seems to be a valid approach, and the "clinical" aspects fully depend on how well you apply maths to your game (or app in general). See this article about the theory of our brain being a Bayesian computer [zdnet.com] or look up the math of for example traffic jams [tu-dresden.de] - they are quite "calculable".

      "Tuning" in general might be a good thing, but you need to base you optimization on something - why not math? The

      • well, there is quite a lot of math happening in our brains (and withing human behavior) at any given time

        That's not really "math" in the way you mean it. It's a form of computations, yes, but closer to an analog computer than a digital calculator. The brain does arithmetic quite poorly.

        "Tuning" in general might be a good thing, but you need to base you optimization on something - why not math?

        Because the results of some random calculation will feel "cold" and not at all enjoyable. Or to put it another way,

      • I disagree that tuning is just a way to work around an inferior AI. When you're only playing against the AI then tuning doesn't matter nearly as much since you can easily make the AI cheat to make up for its deficiencies. Where the tuning really matters is in PvP. If the player perceive (or even mathematically determine for themselves) that one faction/unit/tactic/etc... is "better", then you tend to get very one-dimensional online battles that get boring very quickly. If everything is about equal then
        • I would say that games with poor AI commonly use tuning to help the AI compensate against the human player, but then they also use things like giving the AI a large # of units to start with, or bigger/multiple enemy bases compared with the human's starting forces, etc-- the early C&C and Warcraft games were famous for this, for example.

          I would agree with the notion that tuning matters a lot in PvP, to make sure there isn't one "best unit" or "best weapon" that can be consistently used to win against peo
      • Re: (Score:3, Interesting)

        BlackEmperor writes: "Is the intelligence of an object being tuned (cool)" or is the object just being given a x% production/whatever boost (sucks).

        "Intelligence" generally does not have a "knob" that you can simply tune up and down. How smart a character acts is an emergent behavior that depends on many other factors in the system, themselves which include many tunable knobs like "x% whatever boost", and complex dynamic behavior scripted into the code.

        That said, you can still add more layers to tune

      • Jumping in FPS's is horrible. Thank you Gears of War for eliminating the possibility of Bunny-Hopping.
        • grumble

          Bunny-Hopping is a VERY specific thing, related to the HL engine, having to do with gaining speed due to the funky way airspeed works.

          Peopel bouncing around like idiots is NOT bunny hopping, it is people bouncing around like idiots (and thus making them EASY targets that can't acuratly fire back).
      • I agree. It's that much *sweeter* if I come top of a BF2 team with just the anti-tank guys shotgun (my fave weapon) because I know it's generally thought of as pretty poor. If all the weapons are equal in balsnce does it really matter so much which one I decide to outfit with? I love the idea of fighting against the odds, or turning and running like nuts when I see the guns some other guys have got. People concentrate too much on scores, winning, and balance, when they forget the FUN bit.
        To be honest, I don
        • An exelent example of risk/Skill vs reward would be QIII maps. The standard required to get the rail gun is to put yourself in a compramised position (requires a LONG jump that leaves you open, place it on a platform where you have 0 cover, etc), and often it requires atleast some level of skill to get as well.

          So there is a pay off for a rather heffty reward.

          On the flipside I can easily balance a rocket launcher vs a MG, how? For the RL tweak up reload times, tweak down projectile speed and walking speed,
          • A machine gun is much more accurate than a SMG - as long as you are not shooting point blank.
            Machine guns (light machine guns at that, 7.62 or more mm caliber) have wind adjustments on sights, can shoot cover fire at 600m, have iron sights for up to 1000m, and can fire rather precisely (antisquad automatic fire) at 300m. Machine guns (7.62mm - not squad automatic weapons) can fire to 1500m.
            SMGs and pistols are only usable when you see the white of the enemies' eye
        • I don't think balance is a good idea if it means every weapon, unit, or strategy has a use on every map. Maps should be unbalanced. The advantage goes to the player smart enough to figure out which weapons, units, or strategies are effective on a given map.

          That can ruin the replay value, but replay value is somewhat inimicable to the "Aha!" moment you get when you realize the key to a map. Sure, after you figure out the killer strategy on a map, it isn't challenging anymore, but you get a rush from figur
        • And sometimes this needs to be tweaked. If the first thing everybody does is ignore the machinegun and rush for the RL/BFG, you may have a problem. If everybody with experience goes after the MGs soley, then you may be overbalanced the other way.

          'Day of Defeat' seems to have found a nice balance, people pick their guns based somewhat on preference, but also upon the needs of the map. Some maps you want every sniper you can get, others they're virtually useless.
  • developers (Score:3, Insightful)

    I always figured that there was some sort of mathematical tuning in videogames. I mean, there has to be a better way of balancing a game than just plugging in numbers by trial and error. Maybe its that i've played too many RPGs where math is an obvious factor, but every punch or every bullet has a numerical value right? It only makes sense to me that there would have to be some kind of number crucher on the dev team.
    • I mean, there has to be a better way of balancing a game than just plugging in numbers by trial and error.

      It's not trial and error. It's a binary search algorithm [wikipedia.org] that executed within O(log n) time. :P

      Think of it like turning a knob back and forth, getting closer to the setting you feel is best. The "best" setting is the one with the most appeal to humans, and may not be the most realistic. Unless you're programming an accurate simulation, that is. In which case the players are usually willing to put up wit

      • Re:developers (Score:4, Insightful)

        by paeanblack (191171) on Wednesday January 24 2007, @06:02PM (#17744928)
        It's not trial and error. It's a binary search algorithm [wikipedia.org] that executed within O(log n) time. :P

        Think of it like turning a knob back and forth, getting closer to the setting you feel is best.


        That method will only deliver a local maximum of a polynomial function. If your game has any complexity at all, your proposed method is even less useful than trial and error.

      • Yes, however if you have ever actualy played an FPS (say HL2) on different difficulty levels you will see that ALL they do is tune the damage. I am currently playing through HL on the hardest dificulty level (after having played through on normal a few times), and it is rather hard, but only because it takes more shots for me to kill things (this holds alot of weight as ammo seems to be avaliable in the exact same quanteties as in normal mode), and fewer shots to kill me.

        You are right about everything else
  • by 6350' (936630) on Wednesday January 24 2007, @02:48PM (#17742006)

    We set Medium difficulty to be equal to the mean values, Easy difficulty to be equal to the mean minus a certain amount of standard deviations, and then Hard difficulty equal to the mean plus a certain amount of standard deviations

    Wow. If this is "mathematical modelling", then me swapping the coffee mugs out for wine glasses in my kitchen cubbard would be "advanced sphere packing analysis and optimization".

    Game tuning as more art than science. The goal is not to create an interestingly distrubuted difficulty curve, but to create an "easy", "medium", and "hard" amount of enjoyable challenge. Huge amounts of time can be (and frequently are) wasted focusing too-strongly on a "cool" and intriguing difficulty model that some under-experienced junior designer is all fired up about, instead of keeping the focus tightly and solely on the how the game actually feels.
      • Re: (Score:3, Interesting)

        The sad thing is the article teaches people the tools but not when to apply them. For example, it introduces the normal distribution, but no tests to check the normal assumption on a dataset are given. It also ignores the incredibly important subject of outliers. So in the end, he balances his game using a mean and variance, when its quite likely that a median and percentiles would have been better. Oh well.

        I am constantly amazed at how much game programmers know about the mathematics and algorithms for
        • I am constantly amazed at how much game programmers know about the mathematics and algorithms for computer graphics, and how little they know of everything else.

          As a graphics programmer myself (though not for games), I can say that it's really mostly geometry. In order to get speed, the geometry is tortured into a form that can be difficult to understand, but ultimately it's just geometry.

          Even relatively simple mathematical concepts like sampling theory are above the heads of most day-to-day graphics

        • The sad thing is the article teaches people the tools but not when to apply them.
          That's going to be covered in part 3:

          In the rousing conclusion to this series, I'll be taking bits from parts 1 and 2 and then putting them together in ways that actually have some relevance to games. Or I'll croak trying!
          Could it be that you didn't make it to the end of the article?
  • by onion2k (203094) on Wednesday January 24 2007, @02:50PM (#17742058) Homepage
    I'm a bit of a fan of computer games. I've been playing them pretty close to my entire life. I'm 29 now and since the days of the Zx Spectrum I've probably played at least a couple of hours a week, often much more.

    Unfortunately I suck at games. My coordination is all over the place. I have NO patience. I play games for a laugh, I don't want to invest a great deal of time learning a game or practising it. I want to pick it up, play for a while, and be entertained. As a rule I always play games on Easy because I don't want a challenge. I don't want to get frustrated playing the same level over and over. I want that feeling of progression like I'm getting somewhere. I can honestly say that if I get stuck for more than an hour in a game it gets turned off and never switched on again. I make a mental note not to buy a game from the same people again.

    Easy is for people like me. Lazy, good-for-nothing "casual" players who have no skill to speak of and a life of some sort that means there isn't the time to learn perfection. I expect Easy to be easy. I very much doubt that "mean minus standard deviation" of some enthuiastic professional testers or Beta players is really going to be down at my level.

    Please, for the love of Mario, when you're writing a game, sit your mother down in front of it for a few hours and tweak the difficulty of "Easy" to something she can cope with. That way I might buy your sequel.

    Alternatively, give me God mode. :)
    • I agree, and what I really like is when games take a metric (like failed attempts to complete a task) and use it to kick you to easy mode automatically. Devil May Cry is my favorite example of this. I *loved* the game on easy, and just couldn't stand it on normal/hard.

      Easy should be just that - easy. Makes me feel like I'm having fun, not getting a whipping.

      -WS
      • What I like even more is games that lower the difficulty of a given task after each, say, 3 failed attempts, and then return you to whatever difficulty you were at beforehand afterwards, or else allow you to switch the difficulty up and down without starting a new game. It's annoying as hell when you have to play an entire game on 'Easy' when you know you could do it on 'Hard' except for that one retarded level / boss / series of tricky maneuvers / whatever that you just can't seem to figure out the 'right
        • What I like even more is games that lower the difficulty of a given task after each, say, 3 failed attempts, and then return you to whatever difficulty you were at beforehand afterwards, or else allow you to switch the difficulty up and down without starting a new game.

          You mean like in Crash Bandicoot where you get a free Aku Aku to protect yourself if you die too many times before reaching the next checkpoint?

          Yes, that is a nice feature. Of course, I wouldn't have needed it if I had figured out earlier tha

    • Re: (Score:3, Interesting)

      Sid Meir Solved this problem years ago: Have a whole slew of difficulty levels from braindead to impossible. Somehow I doubt he needed much math for the easiest Pirates! level, where it's nearly impossible to lose in any situation, and in a few minutes play time you are god of the sea.
    • "Unfortunately I suck at games. My coordination is all over the place. I have NO patience."

      And unfortunately, it's people like yourself that take away what makes games great: Interactivity and the depth of control and manipulation you have over you virtual character. That sense of control, the challenges that you overcome while learning a game are what make games great to begin with.

      Imagine prince of persia on "automatic" where the computer navigates the level and fights for you. Not a game I would want
      • I hate automated gameplay with a passion, why not just put the character on autopilot and watch the whole game?

        Angband has a fully automated AI player. While it works, it does have some quirks and sometimes gets perma-killed.

        That being said, fully automation only works if the gameplay style has a predictable combat system that the player is fully able to control. As soon as there's something that wrecks automation, the player needs to switch to damage control mode.

        Here's some examples of some nasty things

      • You could play Dune 2, in which you must give every single unit an order. So: Click the troop, click where you want him to go. Rinse and repeat for however many you have. I think they at least attack automatically...

        Or, you could play Starcraft. Click+drag to select a squad -- up to 12 units, where some units (dropships, overlords) can carry other units inside them. Click where you want them to go, watch them attack anything they find (or run, depending on what mode you have them set to).

        Or, you could pla

      • If you can't commit time to gaming

        I think you should rethink the meaning of the word "game". Chess players don't want to have to play against Deep Blue every time; it's more fun to be able to play a game where you can win, and you shouldn't *have* to invest time into enjoyment. Varying difficulty settings are there for those who want a greater challenge. For you the challenges that you overcome while learning a game are what makes games great to begin with. For others, games are a way to relax away from t

    • I expect Easy to be easy. I very much doubt that "mean minus standard deviation" of some enthuiastic professional testers or Beta players is really going to be down at my level.

      Maybe, but that would be a problem of not getting a representative sample. Statisticians aren't normally fools. They know that anyone willing to sign up for a beta isn't going to be a good sample of the people who buy the game. They can either try to somehow correct for this based on previous data (beta players are 30% faster at fi
    • Alright, you do have some valid points.

      One thing I should mention, some people do improve their games by making them easier -- or at least consistent in their difficulty. Jak & Daxter was mostly easy, partly because you could skip most of the game, by choosing easier alternatives -- it's a pretty open game; each area needs x number of Power Cells, and there are probably 2x or 3x quests you can do in that area which give you a Power Cell. But some parts were hard; for instance, the final boss is very di

  • The article is essentially a fluff piece, but crammed between the useless paragraphs were occasional nuggets of practicality. The important thing to take away is that numbers are important in data models (which is what balancing a game involves.) Statistics is one way to quickly and abstractly summarize a lot of numbers. Read on for a boring, detail-oriented analysis:

    While the article doesn't present it well, I think that the author probably is very good at tuning games. He doesn't come right out and
      • Balancing by numbers/statistics should only be done once the raw gameplay is already in place. If you don't have a playable implementation, balance discussions are purely hypothetical with all the false dilemma and overlooked factors that implies. Once an actual problem or imbalance is identified, numbers can be used to figure out a better value. I expect this applies to computer games as well, but all my experience is with board and card games.

        Another interesting thing to note is that extensive use o
  • As I understand it, they are basically making 'Hard' be 'As hard as possible and still beatable based on previous user performance'. I would get bored with a game like that and stop playing it after not very long. Back in the day, I was pretty good at Starcraft (not as good as some of those disgusting fast Asian kids these days, but pretty good still.) Know how I got that good? Getting my ass handed to me over and over again, finally winning, and then designing an even more diabolically difficult level
  • by SimHacker (180785) * on Wednesday January 24 2007, @03:24PM (#17742518) Homepage Journal

    Sims Designer Chris Trottier on Tuned Emergence and Design by Accretion [donhopkins.com]

    The Armchair Empire interviewed Chris Trottier [armchairempire.com], one of the designers of The Sims and The Sims Online. She touches on some important ideas, including "Tuned Emergence" and "Design by Accretion".

    Chris' honest analysis of how and why "the gameplay didn't come together until the months before the ship" is right on the mark, and that's the secret to the success of games like The Sims and SimCity.

    The essential element that was missing until the last minute was tuning: The approach to game design that Maxis brought to the table is called "Tuned Emergence" and "Design by Accretion". Before it was tuned, The Sims wasn't missing any structure or content, but it just wasn't balanced yet. But it's OK, because that's how it's supposed to work!

    In justifying their approach to The Sims, Maxis had to explain to EA that SimCity 2000 was not fun until 6 weeks before it shipped. But EA was not comfortable with that approach, which went against every rule in their play book. It required Will Wright's tremendous stamina to convince EA not to cancel The Sims, because according to EA's formula, it would never work.

    If a game isn't tuned, it's a drag, and you can't stand to play it for an hour. The Sims and SimCity were "designed by accretion": incrementally assembled together out of "a mass of separate components", like a planet forming out of a cloud of dust orbiting around star. They had to reach critical mass first, before they could even start down the road towards "Tuned Emergence", like life finally taking hold on the planet surface. Even then, they weren't fun until they were carefully tuned just before they shipped, like the renaissance of civilization suddenly developing science and technology. Before it was properly tuned, The Sims was called "the toilet game", for the obvious reason that there wasn't much else to do!

    Here are some questions and answers from the interview with The Sims designer Chris Trottier:

    [...]

    Q: On paper, a game where you simulate daily life doesn't sound that interesting. Yet The Sims is really fun to play, so much so that it is now the biggest-selling PC game ever. Although any development team working with Will Wright has to feel confident in the product they are creating, has the unbelievable popularity of the franchise shocked even the development team?

    A: Absolutely. When I was first assigned to The Sims, it was not-very-affectionately-known within the company as "the toilet game." Will Wright had tremendous stamina for the risk involved with trying something very new, but there were certainly a lot of head-scratchers both on the team and outside of it. In all honesty, the gameplay didn't start to really come together until a couple of months before ship. Being involved in that tuning process, and seeing the game take shape from what had previously been a mass of separate components, was one of the most powerful experiences of my career.

    [...]

    Q: What makes The Sims massively popular with female gamers, who traditionally don't make up a big number of gameplayers?

    A: It's so hard to answer that question without making broad, sweeping statements that anyone of my gender would probably resent. But... I can say that there are several untraditional forms of gameplay in The Sims. For instance, there are many people who spend most of their time decorating and redecorating their homes. Since there's so much user-created content being posted on websites, they spend a lot of time collecting more looks to add to the game. There are also a lot of people who enjoy having a fantasy life where they get to call the shots... for good or for bad. I've heard a lot of stories

    • The essential element that was missing until the last minute was tuning: The approach to game design that Maxis brought to the table is called "Tuned Emergence" and "Design by Accretion". Before it was tuned, The Sims wasn't missing any structure or content, but it just wasn't balanced yet. But it's OK, because that's how it's supposed to work!

      Long story short: you throw all the game elements in a pot, then figure out how to fit them together in a way that's "fun". Failure to do this results in a failure to

      • Re: (Score:3, Insightful)

        While I really have to apologize to the author of the game for using it as an example, 2H4U (Too Hard for You) demonstrates exactly what happens if you throw all the elements in the pot, but don't take the time to balance and tune them

        to be honest, I read the name and the premise and decided not to download. there is no reason for the premise to be exciting. it's more of a demonstration when you throw all the elements for one meal into one pot, and all the elements for another meal into another pot, and th

  • I've played games that have done this in the past and done it wrong.

    Basically, the game "watched" me get better at playing a certain level of the game... unsuccessfully. But, apparently it saw that I was doing soooo well, that it decided to increase the difficulty without telling me. Which actually made me continue to fail to complete the level. Quite frustrating, not to mention annoying to have to keep an eye on the difficulty level so that it doesn't go beyond what you want.

    IMO, Ratchet Deadlocked did
  • my take (Score:2, Insightful)

    I'm a mathematician and amateur game programmer. The problem I have with tuning is that you aren't paying attention to the actual game design when you make stupid changes like adjusting health/damage parameters. Games can be equally hard but not equally fun. If a boss (or level, or anything) is too hard then maybe the problem is with everything else in the game up to that point which did not prepare the player for that challenge. i.e., the player should have had opportunities to learn the techniques nee
  • Wii sports has a rating for your user, and changes the difficulty based on your performance.
    For example in Tennis it's become noticably harder at the 500 level, while at the 0 level the computer is trivial to beat.

    I think satisfaction happens when the game is hard enough that failure is a realistic possibility, but you still tend to win more often. You can tune on the players performance, or a sample audience performance, it doesn't really matter.

    Some hardcore games tune ultimate hardness with the intent of
  • How would you ever tune this game? I have been playing it for nearly five years, including all of its mods and new developments. Tuning it is nearly impossible because the tactics employed by new players are so vastly different from veterans that I cannot fathom how it could be done mathematically.

    Nevertheless, if you coders want to go at it, its open source. Go to the Bear's Pit.

  • in an environment ultimately based on 0/1, by flavor ? :D