On RNG – Lies, Deceptions and Misinterpretations

Warning: This blog post is extremely heavy on the mathematical side and does not have much direct relevance to BDO gameplay. There were feedback that asked for more maths-orientated posts, so this is an experiment on how much demand there is on this type of content. Read this if you want to understand RNG. Do not read this if you don’t care about maths.

  • RNG is by far the most misunderstood popular concept in the history of everything.
  • RNG is frustrating, it makes people want to ragequit.
  • RNG is without skill, and your outcome rests solely on a dice roll.
  • RNG is psychologically rewarding through Operant conditioning, no matter how much you want to deny it.
  • RNG is part of almost everything in BDO.
  • But luckily, RNG does not actually change your fate in BDO.

I’ve wanted to write an article on RNG since I started this blog, however I never found a good way to discuss this topic in a relevant, succinct and straightforward manner. RNG is a complex issue that had been constantly misunderstood by people since the beginning of time. In fact, interpreting RNG is so hard that even scientists cannot easily explain the foundation statistical concept known as the p-value.

Today after seeing a reddit thread, I was inspired to make this blog post. Of course I was inspired because of how misleading that thread was, otherwise I’d just copy it here with credits. Nevertheless, it showed me the exact angle in which this topic should be best explained.

Look at these two pictures:


  1. Which one was definitely generated by a RNG generator and which one was deterministic?
  2. If I gave you magical sand and asked you to spread it randomly and continuously gather and spread it again, which pattern would I more likely make?

Before we start, let’s assume both pictures have the exact same number of dots.

And here are the answers:

  1. We don’t know for sure.
  2. Both are equally likely.

The first answer should be easy to comprehend. An RNG mechanism of spreading dots on a sheet can produce literally any pattern. In fact, the dots can simply create a smiley face shape or all be confined to the top left quadrant of the canvas, albeit both extremely improbable.

The answer to the second question? The picture is just as likely to spread itself into a smiley face as it is to copy the left picture exactly.

Too deep down the rabbit hole? Don’t worry, this article ends with a very simple conclusion that everyone should take home.

This can be difficult to comprehend, so let us explain this by first cutting the canvas into discrete blocks. A canvas of X pixels height and Y pixels width can be:

  1. Cut into a canvas of X times Y number of boxes.
  2. Each box has a chance to contain either a dot or no dot.
  3. There are n dots in the canvas.

Therefore, the number of combinations the dots can take is finite. Because this concept applies to any number of dots, I’ll simplify it by demonstrating what I’m talking about in a 3 by 3 tic-tac-toe tiny canvas with n = 3 dots.

Mathematically, we know that 3 dots on a 3×3 canvas has a total of 9 Combination 3 solutions, thus 84 possible arrangements.

Here are examples of three arrangements.


Which one is truly RNG? Which one is more likely to appear?

The answer is that all 3 can be generated by an RNG generator, and that all 3 have an equal probability to appear.

The probability to appear for each combination of black and white boxes can be calculated by the equation:

p(black total) * p(black total -1) * p(black total -2)

Which in mathematical form is:

3/9 * 2/8 * 1/7 = 1/84

Each combination has a 1/84 chance to be produced. There are 84 combinations.

To conclude partially, the above explanation shows that:

  1. Any pattern can be generated by a true RNG generator.
  2. It does NOT show that every pattern is generated by a true RNG generator.
  3. It does NOT show that there are no RNG generators that are inherently shit.


Now consider two sequences:

  1. 0101010101010101010101010101010101010101010101010101010101010101
  2. 1101000101011011100010101010110000011000001011110101000001000001

Which one is more likely to be generated by a true RNG generator? Still the same. But let’s ask a different question, which is more likely to be generated by a fake RNG generator?

The first sequence can be eyeballed and a pattern is already apparent. It is 01 repeated 32 times. The second sequence wasn’t generated with a pattern; I generated it with random.org.

Knowing the probability of both is not important if you want to know whether the pattern is surely random, but it is important if you want to know the odds of the RNG generator behind the sequence being a good RNG generator (i.e. closer to random).

We can now map the odds into a grid:


This is not an advanced mathematics class so I won’t go into the several methods one can use to calculate the bottom right box, all you need to know is that it’s pretty much as low as the probability of it being truly random.

In other words, the odds of:

  • The first sequence is 18,400,000,000,000,000,000 to 1 in favor of fake RNG.
  • The second sequence is about 1 to 1 in favor of nothing.

We can therefore make a probabilistic claim that the first sequence is not actually RNG. We cannot make that claim for the second sequence.

Let’s go back to this picture:


The same method can be applied to these pictures but because this is not an advanced maths class I will not do it step by step. The conclusion using a similar randomness approach to the above is that:

  • The left side image is probably generated by RNG.
  • The right side image is probably generated by a mixed RNG algorithm. It is rigged by a formula which decreases the probability of a dot being close to another preexisting dot.
    • MOBAs such as DotA and LoL use something similar to the image on the right side to reduce the snowball effect of RNG streaks.

The correct conclusions to draw from the reddit thread is:

  • The left side image in its exact form is more probable than the right side image to appear in a true RNG system.
    • [False]
  • The left side image is RNG, the right side isn’t.
    • [Impossible to determine with certainty]
  • The left side image is more likely than the right side image to be generated with a true RNG generator compared to a partial/fake one.
    • [True]

The most beautiful part of all of this? None of this is relevant to BDO at all. Suppose a square X unit tall and width represents 1 hour of grinding loot, now consider these two images:


If I place the same red box on the image randomly (simulating 1 hour of grinding), which side is more likely to give me a higher number of drops?


If I place the same red box on the image randomly (simulating 1 hour of grinding), which side is more likely to give me a higher number of drops?

The answer to both is it makes no difference as long as the algorithms do not use the red box as a variable. In other words, as long as BDO RNG isn’t controlled by a temperamental gnome that hates you, it honestly makes zero difference which formula it is in the long run. However, the smaller red box is likely to give larger fluctuations in the number of loot you get. This applies no matter whether you look at the left side or right side.

In fact, we can magnify both images to simulate events with low probability of occurrence, such as obtaining an Ogre Ring…. If you’re smart you’d realize that it has the same effect as making the red box smaller.

In other words:

  1. If an occurrence is more common, randomness becomes lesser of a factor.
  2. If the RNG dice is rolled more times, randomness becomes lesser of a factor.

To summarize, I will show you two graphs.

This is the cumulative probability graph of an event tested to be 10% success chance in game over 1000 tries using a real RNG generator.


This is the cumulative probability graph of an event tested to be 10% success chance in game over 1000 tries using a broken RNG generator that has double the chance of rolling 9.



So the final TL;DR:

  1. A true RNG generator has an equal likelihood of producing both images.
  2. RNG generators can be tested for randomness using many methods including statistics, transformations, string complexities, etc.
  3. The left image is more likely to be generated by a true RNG generator than a deterministic or partial RNG one.
  4. The right image is more likely to be generated by a partial RNG generator than a true RNG one.
  5. None of the above actually matters. In other words, the reddit thread posting that image was a red herring.
  6. What does matter is the frequency of RNG dice rolls and the frequency of success in each dice roll.
  7. Although I have to admit if BDO uses an algorithm like the one on the right, it will smooth the progression curve at least in the early stages.
  8. Point 7 shows why it can actually be beneficial to have rigged RNG systems, as long as you’re not the variable being rigged against. And you aren’t, so tinfoil hats off please.

The entire point of this long blog post? The effect of RNG gets lower the longer you play. Simple right?


26 thoughts on “On RNG – Lies, Deceptions and Misinterpretations”

  1. Fantastic post! The lack of understanding in the BDO community as to how randomness occurs is more than a little bit frustrating. My responses to people complaining about it have devolved from trying to explain to just telling people they are bad. Now i have something solid to link to them instead!

    I have to say though, when I saw the first comment on here was “RNG is RNG” I wasn’t sure whether to scream or laugh. There is someone in every discussion that states this and I can never tell if they are serious or trying to troll (though I think its mostly serious). It is especially infuriating when the discussion is based on possible extra variables that may affect drop rates. For some reason, stating that there is ultimately still a randomness factor in the game leads them to believe that there aren’t ways to alter that. IE if you can farm for 2 hours and not get a drop with a 1% drop rate, and another 2 hours with a 2% drop rate with no drops – there is no point in going from a 1% to 2%. Sorry for the off topic rant, but it has been aggravating me for some time now.

    Have you considered doing any testing on possible drop rate alterations outside of those that we know about (node level, S rank etc.)? I’m particularly interested in whether an area being heavily farmed lowers each mobs chance to drop green+ items.


      1. I did a bit of informal testing before Mediah hit, tracking income/hour when grinding during prime time and early morning before work. The difference in value gained was kind of ridiculous, often netting more than 50% higher income in the morning. I tended to solo grind in the basement of calph shrine (and later helms), but I only kept track of income/hour when I didn’t have consistent problems. I also paused the timer before PKing (this was back when xp actually took time past 51 and you lost xp from being PKed, so most people didn’t come back and I was able to keep my spot clear). It wasn’t the most scientific test ever, but it was enough to convince me that there is something we don’t know about that affects drop rates of greens+. The discrepancy in turn in items was always negligible and thus not the reason for the income discrepancy.

        Beyond this, anecdotal evidence supports this relatively strongly. The easiest visible example is grinding right after a server restar,t and especially when new content releases (where the mobs have never been killed). This almost always results in vastly more frequent rare drops.


      2. I personally have never noticed this. So you’re saying trash drops don’t change but you think gear drops do?

        If the sample size is small this can easily be explained by fluctuation though. I won’t tell you it’s definitely wrong right now, but the odds of it being right is very low.


  2. The biggest problem with RNG is that we don’t have a dataset large enough to verify the randomness. You can’t just enchant 10000 pri Ogre rings with 25 failstacks to verify that the chance of success is what it’s supposed to be. We just have to blindly believe that
    – BDO has a “true” random generator or
    – BDO has a skewed random generator that isn’t skewed by some machination to increase cash shop purchases. For example a 35 stacks attempt has a smaller chance of success than a 25+Valk’s cry one.

    While the second sounds tinfoil, there are multiple events when “tinfoil” was found true in games. For example the World of Tanks matchmaking system was PROVED to be skewed by finding an obscure patent where the developer flat out describes how his “random” matchmaking makes sure that everyone has near 50% winrate. I strongly suspected that after playing with an account where I purposefully played horribly and got BETTER rewards than on the account where I played with very high scores: http://greedygoblin.blogspot.hu/p/dont-play-world-of-tanks.html

    Planetside 2 devs slipped that their random matchmaking is actually an ELO system while hiding the rating, getting similar effect. EVE Online Dev “T20” had to apologize for rigging the RNG to provide valuable loot for his in-game friends. CS:GO has a lawsuit for allowing third party “casinos” use its services which were caught to be rigged.

    When someone says “it’s fckn RNG”, he actually means “this is something out of our control or even comprehension”, which can (=/= is) unfortunately be true.

    Having a trusted third party providing the RNG for game companies would greatly help, but for “some” reason game devs don’t want that.


    1. Indeed RNG can never be 100% verified, however I think you are making the same mistake the reddit thread author did.

      It does not matter how many times tinfoil theory is proven right, because the amount of times they are proven right is vastly outnumbered by the amount of times they are wrong.

      So yes, you can find examples of tinfoil being right, but the odds are heavily against you. It therefore becomes irrational to take tinfoil seriously until you have some evidence.


      1. It’s not that it can’t be 100% verified, it can’t be verified at all, since a single player has very limited dataset, one that is completely insufficient to evaluate randomness. If you can flip a coin 10 times, you can’t tell if it’s properly providing 50% heads.

        There is no transparency, while there is clear motivation to rig the RNG, the same motivation why it exists at the first place: because many people rather gamble against odds than accept the mean price for mean result (keeping your money is a better choice than buying a lottery ticket, yet lottery tickets sell). So why not skew the odds to make the habitual gamblers spend more on the game?


      2. It can be verified on a probabilistic value. For example look up the Diehard tests used to test randomness.

        As for your second point it’s an interesting perspective. If this was politics I’m sure they would already have done that. I can’t say with certainty, but that’s too malicious to be used as a serious hypothesis at this point.

        I won’t say it’s impossible but if I had to make a decision I would vote very unlikely.


      3. There is one more thing to consider here, the cost of mistakes:
        – a false positive (calling a fair game rigged) is cheap: there are thousands of good games out there I won’t play because I simply don’t have time. If I don’t play a good and fair game because of tinfoil, and play another one instead, I lose very little
        – a false negative (calling a rigged game fair) is very expensive: you get invested into a game with many hours that gives you frustration in return. I almost broke up with my girlfriend because of World of Tanks, as we both had better solo stats than when we played together and blamed each other for the defeats. Then we started various tests and found that the game is rigged (later proved by finding that patent). In EVE I spent countless hours just to get open harassment from devs just because the opposing team had media partnership with the devs (the opposing team second guy carelessly acknowledged this in a post, so it’s not tinfoil).

        Ergo, even if the conspiracy theory is unlikely – but not impossible – it’s safer to just let the game go and play another one. For this reason I don’t play the enhancement game of BDO, I only get gear by buying it from the marketplace. If I can’t buy something, I buy a weaker one. If I can’t gear up because no reasonable gear is available on the marketplace, I’ll quit. But I won’t be cursing front of a deleveling (while I’d gladly pay a determined price in stones that includes the mean value of all opportunities including deleveling)


      4. Your decision is correct regardless of whether the conspiracy theories are true or false lol.

        Self-enhancing gear always more expensive than buying from market.


  3. For some reason there is no “reply” option to your last response!

    I won’t say my sample size was enough to give any definitive evidence, nor was it a “perfect” test by any means. What it was though, was consistent.

    I mentioned the trash drops to reinforce that my kill speeds were indeed roughly the same in the evenings as opposed to mornings. Outside of the trash drops though, the difference was pretty noticeably even at a glance. I got far, far more green drops (armor, trade item turn ins, scroll books) as well as substantially more blackstones. There was quite literally never an evening where I had anywhere even approaching the number of those items that I was getting in the mornings. I stopped gathering silver/hour data after the game had been out for a month and a half or so, but I’ve seen similar patterns appear since then. When MoS were becoming expensive and the drop rate was boosted, I was getting those consistently at a minimum of 1 per hour in the mornings, and rarely had any drop on evenings or the weekend. Of course this could be luck and explainable by RNG, but the same pattern has been repeating anywhere I grind. A quick way to get a feel for this would be to go to one of the lowbie areas that are abandoned and kill mobs for a few minutes – you get a surprisingly high number of blackstones.

    From a developer standpoint, such a system makes sense as (if known) it encourages players to grind in less busy locations, especially during peak hours. This would result in a better distribution of the playerbase over grind spots, causing less of a bottleneck as well as “helping” players experience more of the game world.
    There are a plethora of possible additional factors that influence loot drop beyond what we know. This particular one would explain many of the others and account for a lot of the absurdity we see in drop rates. We know that PA likes to add in random extra things (random stat increases on character level up for example), it wouldn’t be in the least bit out of character to have something similar to this in place.

    All that said, my tests were far from definitive, but are more than enough for me to believe there is something worth investigating here. I may start recording my grind sessions again here soon to see if I still get the same result discrepancies. I should also state, since it is somewhat relevant, that I’m an analyst IRL, so spotting patterns as well as being skeptical of said patterns is a big part of my day job.


    1. I’m not saying it’s impossible, but you would need to log this information down over a week and do statistical analysis to know for sure. It is very probable that it’s just confirmation bias, which is why I’m skeptical about this kind of theory.


      1. I tracked it for a couple of weeks, so I had a decent amount of info. However I was more trying to ascertain my silver per hour rather than attempt to prove/disprove any particular theories. It is possible that confirmation bias has played a part in my belief as to the validity of this theory. However, I’m quite aware of what it is and actively watch out for it purely because I’m used to doing so at work.

        If I am wrong, I think the cause would be more likely due to collection methods. I was calculating the value added to my account based on current market value (minus tax) at the time of grinding for each grind session. As we both know, market value for items in games often fluctuates a decent bit between mornings and primetime. I don’t think could have been enough to cause such a discrepancy, but it is possible.

        My current grind location is horrible for testing this method as it is busy often even in the mornings and has very few rare drops to begin with. It should be nerfed soon though, and then I can do some testing with pirate island, which is as perfect a location as is possible because you can see your exact mob kill count since they each drop 1 bandana at a time. I’ll simply track the items rather than their current value.


      2. The other more probable explanation IMO is that peak hours have more competition, so you don’t always get the full spot to yourself.

        Personally I never noticed, but since I play in Aus timezone (dead hour) my loot stays the same even if you were right I guess.


  4. I guess there is a cap on how long a thread can be, or you’re locking comments? Anyway, I did mention that I only recorded times where I kept the same rotation. I’ll do the real testing at pirates though where time doesn’t really matter as its so easy to keep track of the number of mobs and focus on the mobs per drop etc.


    1. It’s wordpress not me 😦

      Alright, if you get something concrete drop me a msg. Honestly, I highly doubt such a mechanic. If it’s true though, it might completely change how we farm mobs.


      1. I figured it wasn’t you lol. Now that Chimeras are nerfed I’ll have to go back to grinding “real” mobs again and I can start collecting some data.


      2. Hope you’re a heavy grinder :p
        I tried to get some data but since I have a very restricted timeframe to play it’s too hard to test daily fluctuations.


  5. I go in shifts. I’ll go a week or two with no grinding, then I’ll do an hour or two each morning, 2 hours a night and two 10-12 hour shifts on the weekends haha.

    Don’t expect any results in the very short term, but I’ll get something within the next 2-3 weeks more than likely


    1. Kylaria, I believe that loot works much like fishing hotspots. From my data and my experience, loot appears to be shared among players grinding in the “affiliated node” or possibly in some sort of regional breakdown. Ever notice how loot comes in waves? Its like when your fishing an exhausted hotspot and suddenly it resets to abundant and everyone gets a lot of gold fish until its fished out again. This explains why your morning and offpeak hour grinds are more profitable because you are coming across nodes that are “abundant” and not depleted due to heavy farming. it does not matter if they are in your rotation or not, as long as they are in the node on your channel contributing to the depletion of the total available drops it is going to hurt your rate of return. Also supports your after maintenance and patch success, everyone logs in to nodes being chocked full of drops again. Now I know the “RNG is RNG” crowd will always try to say “tinfoil theory” but I just wanted to show you my findings support yours and your not crazy.

      I believed this mechanic is designed to help regulate pricing and availability of certain items and insures there is little deviance to the total amount of one particular item being available.

      All my of data sets taken have a heavier distribution of loot in the first 10-15% of the total time spent grinding that area. If I walk into Rhutums where no one ever goes, I get 15-20 green item drops in 15 minutes and then suddenly it just drops off a cliff to a rate of 1-2 per 15 minutes. This is actually what tipped me off to actually start testing this because it was so noticeable it got my attention. Ive had similar drop rates in hexe early morning when no one else was farming the channel, I got 8 arc shards in 30 minutes and in the next 6 hours of grinding I obtained 6 more. I have since recreated the same distribution pattern of drops in many other nodes on multiple occasions per node.

      Since testing this, I have started to farm Abandonded Monastery and other places to try to take advantage of what I believe is driving my rare drops. I have farmed smaller nodes where I can keep track of other players being present in the farming area during my grind session and have found that instances where I farm a node exclusively without competition yield higher rates of return for rare drops.


  6. I would be 100% with your post if in BDO they didn’t use many things to actually influence the results of the RNG. I did Kzarka for months and get nothing good with it, while everyone even devs were claiming i had equals chance of those looting their 7 kzarka weapon in a row.
    Then i changed a fiew things in my approach, thought about it, took hints of how to loot and only keep the one that were making sense. In the end i did Kzarka 3 time in 3 days and got 3 weapons in a row. Yes of course i could be suddenly reaaaaallly lucky, but i’m pretty sure i was not. The game actually cheat a lot with RNG to push people toward the cash shop, on a game supposed to not be a Pay2win.

    So again i admire your post and it’s really true to me, i mean on a mathematic approach, the issue is that BDO don’t use a mathematic approach, at least we can say there things that influence the results of the RNG based on variables they can control pretty well (Kamasliv blessing for exemple)


    1. Thank you for your feedback!

      While we can’t know for sure, I still believe you just got screwed over by the bell curve. For example, if the drop chance is 1%, 1 in 20 people still won’t have it 300 kills later. That’s the unfortunate thing about RNG heavy systems, it’s nice when you get something, but other times it’s endless frustration.


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