The Death of the DC10? (2025)

Without completely rehashing the conversations that came to light on Discord, I'll summarize some of the key points.

Essentially, the DC10 is one of those elements that the current sequel design retains from TNP; an argument could be made that it's vestigial, or that it's one of those "ship of Theseus" situations -- but on the other hand, you have to start somewhere. Where it seems to be at loggerheads is in the particularly sequel-ish notion of adding flat modifiers into the mix. To wit (and, in short) if the assumption is that your combat rolls will always add your highest stat (i.e. a +2) then the DC isn't really 10, it's more like it's actually an 8.

So, one direction in which that conversation forks off is, how do we incentivize variety in combat modifiers? Well, essentially you would have to structure a class' basic features such that the +2 was always (or at least, often) adding dice to the pool. The math tells us that a +1 increase in attack is about equal to adding one more d6 to the pool, so the bigger incentive is going to be adding the die, because it also adds a d6 of damage (and not just +1 damage.) Alright, but since our acceptable range of modifiers is already so limited (+0/+1/+2) how do you iterate that idea over, say, 6 different classes? This idea also solidifies the notion that the attribute array would have to be limited to a single +2 -- otherwise, you'd put a +2 into your attack stat, and a +2 into your "dice pool" stat, because that's a no-brainer.

Now, this sounds like a nitpick, but part of the reason I chose DC10 in the first place is because of the ergonomics of it; 10 is the first double-digit number, it's also ingrained in 10-fingered humans (which is likely the reason the base-10 number system exists.) But as I've said before on the blog, where it really came from was if you strip away your +3 attribute and +2 proficiency when trying to hit an AC15, the math of +0 vs. AC10 is exactly the same. But that's talking about d20 math, and the sequel isn't in that paradigm at all, anymore.

So the first idea that occurred to me was to strip out the modifiers; to keep the math the same, we'd have to arrive at a DC8 -- at least for a basic combat roll involving 3d6. Well, 5 is a nice starting point (for the reasons mentioned previously) and adding the number of dice to that gives you 8. So maybe the DC is "5 + [number of dice]" instead of just a flat 8. What I quickly found with that is the DC escalates slightly, for almost no meaningful change in hit-chance; this felt like it was adding overhead to the mechanics with no subsequent added functionality.

Building off of that, the next idea that popped into my head was, "what if the DC was [number of dice] * 2?"

What this would functionally do is lower the DC of the 'basic attack' down to 6, giving a much higher hit chance and reliable damage output; it also creates a cap where having 6 dice in the pool bestows steep diminishing returns, and 7 pushes the DC into impossible territory (i.e. 2d6 cannot equal more than 12, and 7 dice would create a DC of 14.)

With a little help from the people who brought you Strike! RPG, I was able to get a very precise calculation as to what the math would look like on this (rather that just ball-parking it, with my limited mathematical knowledge.) Using the two lowest possible dice (which still produce a hit) for the attack roll, and the remaining dice for damage, we get:

3d6 DPR = 3.58
4d6 DPR = 5.40
5d6 DPR = 5.93
6d6 DPR = 3.21

The question then is, does this give us enough flexibility to build out the mechanics? Clearly, the answer is "not quite" since this would effectively cap the number of additional dice you could add to the pool at 2 or 3; the only way you could get around that is to cap the DC at something like 10 -- go figure.

The other thing we have to remind ourselves is that without using modifiers, "only 5s and 6s matter" starts to creep back in. (It genuinely makes me wonder if the Arkham Horror-type games are built around the assumption of 5s and 6s being successes, for this same kind of reason -- or it could just be a coincidence.)

And that's pretty much where I sit, at the moment -- stuck between a rock and a hard place. It seems silly to have flat modifiers that don't matter, but it seems nearly impossible to diversify those numbers, either. On the other hand, if you go back to the paradigm of "attributes only matter for skills" then we've just reinvented d20 TNP (seemingly right down to the DC10, even) -- almost like building that ship of Theseus I mentioned at the start.

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April should be a lot better for sticking to the planned schedule of 5th/15th/25th, so check back on those dates, for more!

Double or Nothing (2025)

I was giving some consideration to the skill mechanic proposed in the previous post; to wit, a baseline +0 mod would result in a straight 2d6 vs. DC10 roll. This has pretty low odds of success (1/6th) compared to the d20 baseline of 1d20-1 being about 45%

So what if we do something with rolling doubles? 5+5 and 6+6 would already make a success, but the other 4 combinations (out of the 36 possible, with 2d6) makes for an 11.11...% outcome; if you add this to the 1/6th chance, it becomes 27.77...%

Now, clearly, based on the numbers in that previous post, we probably wouldn't want to shift all of the other odds up ~11% so probably this mechanic would be limited to when you're only rolling 2d6 on a skill check.

But maybe there's something we could do, using the doubles with attack dice.

If the baseline roll is 3d6 (2 used for attack, 1 used for damage) there are 216 combinations that can result; matching pairs would exist in 36 of those (including triples) 24 of which would be combinations other than [5,5,X] or [6,6,X] ...which again results in 11.11...%

If we go back to another previous post, we laid out the attack math, where a +2 mod resulted in a 68.06% hit chance, and a +1 mod resulted in 52.31%; increasing either of these numbers by ~11% keeps us still well within acceptable hit-chance ranges, which is pretty interesting! The question would be, how do we apply this sort of bonus? A boost of this size actually pretty closely mirrors the usage of "Combat Mastery" in TNP, so it stands to reason that this bonus could apply in similar situations. (The other bonus mechanic in TNP being class dice bonuses, which the sequel mechanics would mirror/mimic by using the d6 pool mechanic.) Also worth mentioning: off the top of my head, it wouldn't change damage-roll outputs very much; only a combination like [4,4,6] would actually produce a meaningful damage boost (by allowing the 6 to be used for damage instead of attack, while still producing a hit.)

I think if the general ethos of the game's mechanics is to roll a pool of multiple dice but ultimately only use 2 of those dice to determine the result, then including something like doubles adds a fun layer to it. Obviously, once we go beyond 3d6 and start to account for a bigger dice pool, the math would get more complicated.

It also recently occurred to me that the previous post basically took the 3d6 math, and put a new slant on it. As mentioned before (when looking to other possible dice mechanics) the ranges for flat modifiers on 3d6 vs. DC10 are extremely narrow; basically only +1/+0/-1. What the previous post did instead, was basically turn the flat modifier into a die pool, using the 3rd die (i.e. 2d6+[highest 1d6, of the pool] instead of "3d6+X"). Having a two-stage skill check roll is still a little bit janky, but I think something like that was sort of inevitable, in a "d6 does everything" mechanical paradigm.

However, by adding doubles to the success pool, we actually decrease the necessity of rolling the dice pool, albeit only by that ~11%. It speeds things up a little, because results like 2+2, 3+3, and 4+4 (which would still mathematically have a chance to succeed, with a 3rd die added to them) are instead just fast-tracked to being successes, bypassing the need for that 2nd-stage of the check.

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One most post is scheduled before the end of March; to try and keep things on track, it'll likely be out by March 28th at the latest.

Reverse Engineering (2025)

I've been thinking on how to handle the skill check mechanics for the sequel, and I realized the original idea had gotten away from me, somewhat.

In TNP, the skill "check" die is a d10, and the bonus die is a d6; to mimic this in a d6 system, the obvious thing to do would seem to be replacing the d10 with 2d6. But somehow I'd gotten to a place where it had morphed into some variation on "d6 pool for everything, all the time," and it still seemed to miss the mark. Without beating a dead horse, the effective mod range is a bit limited, and the dice rolls that matter are likewise pretty limited. So I went back to the fundamental 1d10+1d6 idea.

Ok, let's say the "check" die is 2d6; anytime you make a check, you roll 2d6. Against a DC10, this gives you only a 1/6 chance of success -- so some more dice and/or mods are clearly needed. The average on 3d6 is 10.5, meaning that 3d6 vs. a DC10 is basically a coin flip. What TNP does is essentially increase the number of "bonus" dice you can roll, thus increasing the odds of rolling a high bonus/modifier to your check. We could apply this same logic to a 2d6 system; the base check is 2d6, and the bonus is the highest d6 out of a pool. If we're using the current baselines, this would be a maximum of +2 from Attributes, and probably the same for Skillsets (maybe +3?)

Using anydice, we can figure out the odds for how this works vs. a DC10:

• 2d6+1d6 = 62.50%
• 2d6+[highest 1 of 2d6] = 75.23%
• 2d6+[highest 1 of 3d6] = 81.13%
• 2d6+[highest 1 of 4d6] = 84.37%
• 2d6+[highest 1 of 5d6] = 86.35%

This actually looks really promising, because as the chance of failure drops towards that 15% threshold, the diminishing returns on further boosting a skill start to kick in. Adding the implicit assumption of a 3rd die (except in the case of a +0 mod) also gets around the problem of "only 5s and 6s matter." The problem is that this breaks the check into 2 distinct rolls, which is a bit inelegant; the base 2d6 clearly can succeed, but is unlikely to do so -- but pooling them all together completely changes the math. If the 2d6 is a 3 or less, then the bonus dice become irrelevant (because the check has no chance of success) but a result between 4 and 8 means that success is still possible -- unlike with the "dice pool only" model, where it's just... 2 out of X dice have to equal 10, so if you roll all 4s and 3s (or lower) you're just screwed.

So now that we've established that this works, the immediate question is, can we further reverse-engineer this into a combat system? As I've often said, you should either have a unified system (that usually works great for one subsystem and badly for another) or you have distinct subsystems, but both serve their purposely excellently. The conundrum of an "all d6 system" is that it's not very unified if there are still distinct mechanics for combat vs. for skill checks -- despite everything using the "same" dice. 

The current combat mechanics are based around the supposition of 3d6+mod, where 2 dice (plus a flat mod) are used for the attack roll, with the remaining die (plus the same mod, probably) being used as the damage roll. To make this work anything like the check dice... basically it would mean a significant boost to hit-chance, assuming we're sticking with a cap of +2/+2d6 modifiers (which, you can't really meaningfully go lower than that, so...)

As mentioned in the previous post, the fact of attack rolls having damage as a "release valve" for unused dice means that the attack mechanics will likely/necessarily have to be different than the skill check mechanics. The other consideration is that the "acceptable ranges" for both types of rolls are different; skills should mostly fall in the 45% (i.e. a -1 mod, in D&D terms) to 85% range, whereas attacks probably need to have 55% or 60% as a baseline, and increase to 90% or possibly 95% with teamwork and other bonuses. This all makes it hard to unify mechanics, since unified mechanics should (presumably) produces unified outcome ranges -- so if that isn't the goal, then unified mechanics likewise shouldn't be the goal. This new idea now gives us mechanics that hit both of our prescribed benchmarks; the question next is can we do anything to further simplify and/or unify these two systems, and still produce comparable outcomes?

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Next post is due on (or about) March 15th, so check back then for more!