(+)Changing From a DC Ladder to a Success Ladder

[doctorbadwolf]

I need some help figuring out probabilities in practice with a dice rolling method. I’d be very grateful for any insights y’all can give.

So, my TTPRG, Quest for Chevar, is a skills based game where character creation is very specific, and then gameplay is narrative, player facing, and open-ended. Basically, imagine if instead of the DM in dnd deciding whether something works, your check directly tells you, you say what that means, and the DM smooths over any transitions, NPC reactions, etc. It's a conversational system, but one in which much of the GM responsibility is put into the hands of the group, and the acting player.

Anyway, I've realised thanks to @hawkeyefan @pemerton @AbdulAlhazred @Campbell and others that, among some other insights that will lead to some further investigation, the roll vs DC model doesn't work as well for that, and I haven’t done as much as I can to put things in the player’s hands.

This thread is mostly about the dice. It’s also a plus thread, simply because I don’t want to see it detailed with stuff like “dice pools are bad, actually” or “if you want a success ladder just make it a pbta game”.

What I’m wondering about is the numbers relative to the dice, and how the odds play out.

Right now, the game rolls 1d10 + 1d10 per skill rank. Nothing else ever adds to a skill check, and skills govern everything that is rolled for in the game.

Attributes only interact with skills when you want to spend a resource to improve a skill result.

Each skill, in case it matters, is basically a description of a competence with some very simple parameters.

For instance, the Warp Specialty under the Geomancy Skill allows you to make portals. Making a simple short distance portal between points you can see just takes an action. Doing so as a quick action, increasing distance or size, doing something complex or that requires another skill, or putting one or both portals where you can’t see, all require a skill check.

At chargen, you can have up to 4 total ranks in a skill specialty, for 5 dice, but most of your skills will be from 1-3 ranks.

So, rolling anywhere from 1 to 6 or 7 d10s, what does a pbta style success ladder need to be, for the following goals:

• Each step on the ladder is a range of results (eg 1-8, 9-12, 13-15, 15+)
• Lowest result: Total failure
• One Step Up: Mitigated Failure (you fail, but can still get something out of the action or situation, use the action to set up something else, or otherwise mitigate your failure, or you can bargain for dire consequences or spend an attribute point to get one step higher on the ladder)
• Second Step Up: Mitigated Success (you succeed, but there’s a cost, or you can bargain or pay, as with the first step)
• 3rd Step Up: Total Success.

Probability goals:

• Total Failure shouldn’t be common for trained characters under normal circumstances.
• Mitigated Failure should be all you can get if you are untrained, with no help, an no prep, ie rolling 1 die, and even it should be uncommon (like 8 on 1d10). Most novice skilled checks should fall here and the next step, and it should be fairly rare for masters.
• Mitigated Success should be the most common result for journeyman level characters, so 3-4 ranks.
• Full Success should be possible for anyone with 2 ranks (3 dice) or more (or 1 rank (2 dice) if it can be done, so 20 at most). It should only be common for Journeymen or better, and only really common for Masters.

Circumstance can add or subtract dice, to a minimum of 1 die, max of 6 or 7 (probably).

So with all that, I can input stuff into anydice, but what I have trouble with is math burnout after about 20-30 minutes of reviewing different graphs, and collating that data into a full model I can build from.

Any thoughts? I know it’s a lot of info, but I hope the discussion will be fun for dice nerds?

 

[pemerton]

Are you summing the dice, or taking the best roll? Or some combo (eg Cortex+ Heroic and Agon both, by default, sum the best two dice in the pool)?

 

[doctorbadwolf]

Are you summing the dice, or taking the best roll? Or some combo (eg Cortex+ Heroic and Agon both, by default, sum the best two dice in the pool)?

Sum.

Edit: I find d10s very easy to count, but I’d also be fine tuning numbers down and using d6s. I just prefer the pool of d10’s.

 

[pemerton]

If you're generating numbers on 1 to 6 d10s, and summing them all, you're going to have wide ranges in ability - which I guess you've already worked out.

If you set Total Failure as 7 or less, that will be 70% of 1-die rolls, about 20% of 2-dice rolls, and less than 10% of 3-dice rolls.

If you set Mitigated Success at 15+, that will be about 20% of 2-dice rolls, nearly 65% of 3-dice rolls, and about 90% of 4-dice rolls

If you set Total Success at 20+, that will be 1% of 2-dice rolls, around 28% of 3-dice rolls, a bit more than 65% of 4-dice rolls, and close to 90% of 5-dice rolls.

 

[Aldarc]

I know the OP has me on ignore, but maybe my comments will nevertheless generate conversation that they would find helpful.

There are multiple ways to potentially get the desired results, and playtesting would be required to see what works best for the OP.First, there are some other systems that I could see as possible pools for inspiration:
(1) Ironsworn: a 2d10 PbtA-derived game
(2) Cortex Prime: a dice pool game with a simple mechanic of rolling a bunch of dice and adding two dice of your choice
(3) Blades in the Dark: a game that weds die pools with PbtA design principles - including failure, complicated success, success, and critical success

The benefit of (3) is that it can better account for variable die pool sizes. The OP can key the fail/success states to the sides of a d10. So if you have 1d10, you know what you need, just as well as if you had 7d10.

But if one is hypothetically summing the dice, then I would probably opt for something more akin to Cortex: roll what you have and add. But I would limit the number of dice being added together to two. One could play around with the mechanics a bit. You could tie the success ladder to a range (e.g., failure is 2-10, success is 11-20), have different effects key off die results (e.g., 1 introduces a complication), or even do things with the excess dice (e.g., criticals), etc.

 

[doctorbadwolf]

If you're generating numbers on 1 to 6 d10s, and summing them all, you're going to have wide ranges in ability - which I guess you've already worked out.

If you set Total Failure as 7 or less, that will be 70% of 1-die rolls, about 20% of 2-dice rolls, and less than 10% of 3-dice rolls.

If you set Mitigated Success at 15+, that will be about 20% of 2-dice rolls, nearly 65% of 3-dice rolls, and about 90% of 4-dice rolls

If you set Total Success at 20+, that will be 1% of 2-dice rolls, around 28% of 3-dice rolls, a bit more than 65% of 4-dice rolls, and close to 90% of 5-dice rolls.

That sounds about right. This means that most checks will be a mixed result, unless you’re a Master. It might also mean it’s worthwhile to reduce the number of ranks you can start with by 1, down to 3.

7 as the baseline for non-flub means that a 5 rank character would have to roll at least 3 1s to flub. It could happen, but it won’t happen often.

 

[pemerton]

7 as the baseline for non-flub means that a 5 rank character would have to roll at least 3 1s to flub. It could happen, but it won’t happen often.

If 8 is the requirement to avoid Total Failure, it basically won't happen if someone is rolling 5 dice: about 1 in 10,000 rolls.

 

[doctorbadwolf]

If 8 is the requirement to avoid Total Failure, it basically won't happen if someone is rolling 5 dice: about 1 in 10,000 rolls.

That would match the goals, actually. I’m considering a trait that you could take when you’ve reach max ranks, that makes it so you never get a total failure with that skill, and any dice pool penalty for a check with that skill is reduced by 1.

Basically, you’ll still see some mixed results sometimes with that one skill, but you’ll never flub, and your mixed results will usually be mixed success.

I imagine 6 ranks is basically “you always win” anyway, so 5 ranks might be the max.

Hmm. The original model for skills was :

Skill: ​

Specialty:​

Specialty:​

Specialty:​

when you make your character you get some skills from origin, some from archetype, and a few freely chosen.
For each skill rank you also get one specialty rank.

When you make a check, you usually do so with a specialty, which means you add your skill and specialty ranks together. This effectively means that a skill rank is a rank in each specialty of that skill. When I reference total rank, it is skill+spec.

Generally as you advance, you only gain specialty ranks, unless you train in a new skill, or spend significant resources and/or time on training with the skill. Also for ease of bookkeeping, if you have ranks in all 3 specialties you can convert them to 1 skill rank. Mastery is having 5 ranks in a specialty, with probably a benefit somewhere for having mastery in an entire skill.

But basically this is the only complicated thing in the game, and it’s not as complex as it sounds. PCs don’t really get more health or do more damage as they advance, they just get better at skills, gain new traits, and slowly gain more attribute points to spend on special abilities and on upgrading a check up the success ladder.

Spending all your AP in any attribute has a risk of Trauma, and you only regain a little when you rest, unless you take at least several days in a safe place.

Just in case any of that is helpful or interesting. Tbh explaining it helps me order it all in my head before writing the next draft.

 

[pemerton]

Error in the above: that should be 1 in 5,000 I think , not 1 in 10,000.

 

[doctorbadwolf]

Okay I think I like;

Total Failure: 1-7
Mitigated Failure: 8-14
Mitigated Success: 15-20
Total Success: 16-20

I might drop lower mitigated success but 1 or 2, but I kinda like that mitigated failure takes up more space by itself on the ladder, while the two success states together take up more, so we will see.

max starting ranks is 3, so you can only start a Journeyman, and that only in a few skills. Max total ranks is 5. Further mastery is about mastering related specialties and skills to support what you’re best at, and earning traits that make you more able to do more with a given skill and/or more reliably roll high. For instance a Master’s Focus trait for the Sigils specialty is to be able to create a circle for complex magical workings without having to manually draw it, bypassing the need for a check, and saving time.