A different kind of RNG for D&D 3.X

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Sergarr
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A different kind of RNG for D&D 3.X

Post by Sergarr »

Another RNG thread? Really?

Yes.

So, with the current RNG system (d20+bonuses vs DC), and the usual situation (the number that actually matters in most cases is not a probability of succeeding, but rather an average number of attempts between failures/successes), the +1 bonus can actually have a vastly different effect on your survivability depending on both the DC and your current bonus. Also, there's the annoying effect where, at high levels, even characters of same level that are both supposed to be able to do something can have bonuses to doing that thing, that are not on RNG within each other, due to accumulation of a lot of little +1's little bullshit modifiers.

I've seen some people here that wanted to switch to a dicepool system, but dicepools have a negative side in that, while it's harder to technically get off RNG, practically you do so even faster than in d20 system, and again, that +1 bonus can have vastly different effects, depending on whenever you start near the center of the bell curve or in its tail. Also, it's very hard to figure out how to convert the existing D&D numbers so that they'll continue to make sense.

So, I've tried to make a RNG system that would be:
1) At least somewhat compatible with D&D 3.X and existing numbers in it (so you can theoretically plug it in).
2) Have the system be based around the "average number of attempts before success/failure" as directly as possible.
3) Have a +1 bonus mean the same thing on as large range of possible bonus values and DCs as possible.
4) Do not have a "get off RNG" effect at all.

The result is this algorithm: when you have to roll against a DC, you add all your bonuses and maluses together, add 11 to the result, then substract the DC from it. You should arrive at a number +N, +0, or -N, where N - some integer number. For later reference, I'm going to call it "resolution number".

If it's +0, then you simply flip a coin, or roll a d6 and succeed on 4,5,6 - 50/50.

If it's a positive number, you then roll a number of d10's equal to that number plus 6, and if at least one of them has 10 on it, you succeed.

If it's a negative number, you roll a number of d10s equal to the (module of that number + 6), and if at least one of them has 1 on it, you fail.

What is this shit and why is it so complicated?

The reasoning here is that every +1/-1 in this system, unless it flips the sign of the resolution number, increases/decreases the average number of attempts between successes/failures by 10%, because every new d10 die adds a separate and independent 10% chance to succeed/fail, probabilty of a event "all dices don't roll a certain number" is equal to a multiplication of probabilities for each dice to "not roll a certain number", which means it scales exponentially, and average number of attempts is inverse of probability, so it scales exponentially, too.

Which is about equal to an effect of +1/-1 bonus in in D&D if you roll against DC 11 with +0 modifier - 50% success chance turns to 55% and 45%, which results in about +10%/-10% relative difference in average number of attempts between successes/failures.

So in effect, it's mostly similiar to d20 near the region where chances of success/failure are equal, and diverges as you go away from it.

That also explains why the heck I'm using d10's here, and not d20's.

Where the heck did that "+6" came from?

It's to make it relatively smoothly transition from "likely success" through "50/50" into "likely failure" zone. With 7 d10, chances of at least one of them rolling up 1 (at negative resolution number) or 10 (at positive resolution number) is about 52%, which results in about 2.09 average rounds between failures/successes. It's not as smooth as I'd like it to be, but that's the best you can get with d10s.

This system has me rolling piles of dices, fuck this non-D&D bullshit.

Well, it's not actually that hard, especially seeing that you only have to watch out for dices that roll a certain number - and that's very easy to spot. It's also very easy to extend towards very large numbers - since you don't actually have to keep in mind any numbers (as in most dicepool systems), you can just, instead of rolling all dices at once, roll the first 10 d10s, then, if it didn't show up a single 1/10, roll a second dozen of d10s, and so on. Pretty easy, as long as you remember how many dices you've already rolled.

Wait, does this "no to getting off RNG" business mean that my uber-armored-character can no longer be effectively invincible to the low-level plebs?

You can still become effectively invincible, because the average time between failures scales exponentially with the bonus you get.

For example, at resolution number of +10 (equal to DC 21 - which is already off RNG in normal d20 system), you get 5.4 attack attempts between someone sticks it through the armor. Not that high, right?

If your resolution number on AC check is +20, the average number of attack attempts is about 15.5. Getting there...

With resolution number of +30, it rises up to 37.7 - which is more than a d20 system's maximum 20.

And for +40, it's more than a hundred - 127.3 average attempts, before the poor low-level shmucks get one attack through your armor.

As you can see, there's still enough space in the system for numerically-ridiculously-overpowered shit, unlike in 5e with its "bounded accuracy" crap. And what's more, all these additional little +1 bullshit modifiers that you simply forget about in normal D&D play, they all still matter, even at such high level - because every single one of them still increases that number by 10%. And, they also don't break RNG.

Any criticism?
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Kaelik
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Post by Kaelik »

Your goals, even if they were actually good goals to have, and not at best neutral, aren't worth the work you put in to get them.

Also, why the fuck D10s? I mean, it's better than d12s, but worse than d6s and d20s for having that number of dice, and feeling D&D respectively. Would it really be that much harder to do the math for rolling those dice?
Last edited by Kaelik on Mon Jun 06, 2016 11:31 pm, edited 1 time in total.
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PhoneLobster
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Post by PhoneLobster »

This does not require extensive analysis.

Its a shitty stupid idea implemented with shitty stupid results.
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Sergarr
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Post by Sergarr »

Kaelik wrote:Your goals, even if they were actually good goals to have, and not at best neutral, aren't worth the work you put in to get them.

Also, why the fuck D10s? I mean, it's better than d12s, but worse than d6s and d20s for having that number of dice, and feeling D&D respectively. Would it really be that much harder to do the math for rolling those dice?
The amount of "work" I put into it is about 2 days of being bored, and I did it almost purely because I wanted to know if there is any other kind of RNG that's different from "flat RNG" a la d20, or "bell curve RNG" a la Shadowrun and GURPS. All these other "goals" are something I've actually added after seeing properties of that RNG I've constructed. I think it was worth it at least because it made me less bored as a result.

D10s were chosen because they usually are already used in buckets, and you need buckets of dice for this system. And well, I suppose you can use d20s (counting 19 and 20 on d20 as 10 on d10, and 1 and 2 on d20 as 1 on d10). Or d6s, for a more steeper curve.

It would probably be a better idea to use d6s, actually now that I think about it - because of that "steeper curve" thing, it would be overall a better fit to the existing distribution; thank you for suggestion.
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Post by PhoneLobster »

Sergarr wrote:All these other "goals" are something I've actually added after seeing properties of that RNG I've constructed.
Methodology THEN Goals.

... every time, EVERY TIME.
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JonSetanta
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Post by JonSetanta »

I think I'll just play 5e.
Schleiermacher
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Post by Schleiermacher »

This is hysterically, impossibly complicated for the core mechanic of an RPG.

And unless I've missed something (which is possible, see above) it absolutely requires every roll to be against a known DC, which means you have to be told every DC before you make the roll, and it completely fails to handle opposed rolls and degrees of failure or success. Which means your idea is bad and you should feel bad.
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tussock
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Post by tussock »

OK, so ... really, you're subtracting a reduced DC from your net task bonus to arrive at a somewhat small number. AC 15 -> "-4", +7 attack -> +3.

So then I roll, uh, +6 => 9d10, and check if I got a 10. Which is ... well, uh ... that's ... I'd need to buy some more d10s.

The shortcut seems to be to assume you're rolling against DC 15, note how many dice that gives you (it's your net bonus +2), and subtract 5 dice for DC 20 (net -3), or 10 dice for DC 25 (net -8), except it flips to adding dice at 6, but you shouldn't be rolling that anyway so don't sweat it.


Um, except ...

You've sorted it around 50% success, instead of the 70% success that D&D uses for PCs, where +1 is worth 7% more successes, but 17% less failures where it's failure-critical. Where the bonuses are often much bigger than that, and rip you through to the limit of 36% more successes and 83% less failures.

That's also a thing, where in D&D you're supposed to collect up little +1s to almost eliminate your failure chances, that's the whole point of character building and treasure rewards in many editions (as much as the authors claimed otherwise), including the current abomination. That's why they gave us so many annoying-ass +1s to collect.
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