Having a % Chance of Being Successful at "X", is a very natural way of explaining things.

Why haven't Percentile-Based Systems won out in a big way, in the RPG market?

Thanks in advance, for chiming in.

Quote from: Jam The MF on July 15, 2022, 07:13:11 PM
Having a % Chance of Being Successful at "X", is a very natural way of explaining things.

Why haven't Percentile-Based Systems won out in a big way, in the RPG market?

There are successful percentile systems, notably Call of Cthulhu, which is one of the most popular RPGs of all time. So there's nothing wrong with percentile systems, but I don't think they are seen as markedly superior.

1) Explaining the odds isn't a primary mark of success in a game in general. Few games outside of RPGs use percentile dice either (i.e. wargames, board games, dice games).

2) Bigger numbers mean more difficult math. Adding and subtracting numbers from 1 to 10 or so can be done easily, but it gets harder the larger one goes.

3) Percentile stats make it difficult to express large differences like in high-power fantasy or superheroes, because values higher than 100% are counter-intuitive.

Quote from: jhkim on July 15, 2022, 07:30:50 PM

Quote from: Jam The MF on July 15, 2022, 07:13:11 PM
Having a % Chance of Being Successful at "X", is a very natural way of explaining things.

Why haven't Percentile-Based Systems won out in a big way, in the RPG market?

There are successful percentile systems, notably Call of Cthulhu, which is one of the most popular RPGs of all time. So there's nothing wrong with percentile systems, but I don't think they are seen as markedly superior.

1) Explaining the odds isn't a primary mark of success in a game in general. Few games outside of RPGs use percentile dice either (i.e. wargames, board games, dice games).

2) Bigger numbers mean more difficult math. Adding and subtracting numbers from 1 to 10 or so can be done easily, but it gets harder the larger one goes.

3) Percentile stats make it difficult to express large differences like in high-power fantasy or superheroes, because values higher than 100% are counter-intuitive.

^This, plus having X% chance to succeed isn't that natural when you're rolling against an opposed ability or a certain difficulty that varies by circumstance. In which case you may have to resort to math that would mess up your neatly predetermined % of success.

It's subjective, but I also think that a single d20 roll has a better feel than either two d10s or a single clunky as hell d100 roll. And % values in most systems tend be divisible by 5 anyways, and 100/5 = 20. So if you're (usually) going to be rolling in increments of 5% anyways, you might as well go for a die that's already divided in 5% increments, i.e. the d20 (the most popular die type IMO).

Also, I don't think non-nerds think in percentages, so basing a system around them makes it accessible only for a certain subset of the player base, specially now that RPGs are for cool kids too, not just math geeks.

Because I want to actually use all the goddamn nice I paid for. That may not be the most common answer to the question. But it's probably the best answer. And maybe even the most honest answer.

Personally, I'm very pro d100. At the end of the day, probability is most naturally expressed as a percentage.

However, there is a pecking order of what feels "organic."

A 1 in 3 chance to bash down doors seems like a good, off-the-cuff estimate. Like if you were a journalist traveling through time and alternate dimensions to the fantasy world where a party is actually in a dungeon bashing down doors, and you catch the barbarian in a rare idle moment where he's scratching his ass because his hireling used too much starch on his loin cloth again, and if you went up and asked him, "How many doors would you say you bust open on the first try?" "About 1 in 3" seems like an answer you might genuinely get.

You can ham-fist it into a d20. 7 in 20 chance. Okay, it's not exactly the same. But close enough. Graininess or some such gamer jargon bullshit. And the gamer might even argue, "well *snort* ackchyually, we don't know what the exact probability is because it got truncated to the graininess of the d6. Technically, since d20 is higher resolution, 7 in 20 is likely more accurate."

And yet 7 in 20 just doesn't seem to vibe as nicely as 1 in 3. And maybe it has something to do with wanting to imagine Thorgar of the Itchy Jock rather than Milton, the kid from school who used to get beat up for his milk money.

Percentile, in my estimate, is at the middle of the pecking order. It feels less organic than "1 in 3" but a hell of a lot more organic than "7 in 20." Even though on some level it's just the latter on steriods--33 in 100--because percent is a part of our natural language, it vibes a lot better.


Near as I can tell, the evolution of game mechanics went something like this. You originally started with two game mechanics.
1) Decide on a reasonable probability, and roll whatever dice is convenient.
2) Cross-reference the two relevant values on a matrix to find what you need to roll.

I feel almost every gamer is mixed up on #1. When you have AD&D using d6 for elves to find secret doors and d4 for dwarfs to detect shifting walls and d100 for thieves to find traps, that isn't three different mechanics. It's all the same thing. Figure a probability, and roll whatever is convenient.

It's not without its drawbacks. Like you've got an elf creeping around 90' ahead of the party, able to surprise monsters 4 in 6, but then it comes across an ettin that is only surprised 1 in 10. Technically, you've got 2 salient variables opposing one another. This should be solved by a matrix. But it might seem silly to have a matrix with indices like 1 in 10 or 4 in 6. So if you don't want to go that route, and you don't want to have a stroke doing the math, you need a common denominator.

Which means going back to the organic pecking order, if the top tier isn't working, the only way to avoid the bottom tier is to go percentile.

It's a good way to go. And most objectives to it are completely idotic.

But still, I do want to use all the goddamn dice I paid for.

Simple answer - they're swingy as shit.

Settings is my guess. Outside CoC what cool setting do they have? None. Sure, Glorantha is neat, but definitely not everyone's cup of Joe. That and there's no really good magic systems.

QuoteSimple answer - they're swingy as shit.

But that really depends on how character abilities are counted and developed.

Well, I mean I suppose you could have a percentile system that doesn't use a d100, but... I dunno. The problem with the d100 and the d20 that at a certain point your skill/stat doesn't matter. If the target number is 13, and you're at +6, you have very good odds of it, but there's still a decently high chance that you will fail. More, you still run the risk of failing really easy tasks that somebody at your skill level has no business failing. That's why I prefer bell curve stuff, since that distribution is more like a realistic skill distribution.

Quote from: drayakir on July 15, 2022, 09:35:54 PM
Simple answer - they're swingy as shit.

So is the d20, but that hasn't stopped it from being the market leader.

Quote from: Jason Coplen on July 15, 2022, 09:53:37 PM
Settings is my guess. Outside CoC what cool setting do they have? None. Sure, Glorantha is neat, but definitely not everyone's cup of Joe. That and there's no really good magic systems.

D&D's magic system is crap, but it's still the market leader. Granted I'm not very familiar with any d100 based systems and haven't played any of them in decades, so I'm not sure any of them are any better.

D&D has a couple of cool settings at least, but they've never been its main selling point, and they keep changing the default setting every edition. I'm not sure that's why it and its derivatives are the best selling games.

Quote from: drayakir on July 15, 2022, 10:23:04 PM
Well, I mean I suppose you could have a percentile system that doesn't use a d100, but... I dunno. The problem with the d100 and the d20 that at a certain point your skill/stat doesn't matter. If the target number is 13, and you're at +6, you have very good odds of it, but there's still a decently high chance that you will fail. More, you still run the risk of failing really easy tasks that somebody at your skill level has no business failing. That's why I prefer bell curve stuff, since that distribution is more like a realistic skill distribution.

Do you mean rolling high? I prefer roll under, personally. Both are percentile.

Bell curve ain't bad except for combat, which is a wild affair linear handles better.

Quote from: VisionStorm on July 15, 2022, 10:47:58 PM

Quote from: Jason Coplen on July 15, 2022, 09:53:37 PM
Settings is my guess. Outside CoC what cool setting do they have? None. Sure, Glorantha is neat, but definitely not everyone's cup of Joe. That and there's no really good magic systems.

D&D's magic system is crap, but it's still the market leader. Granted I'm not very familiar with any d100 based systems and haven't played any of them in decades, so I'm not sure any of them are any better.

D&D has a couple of cool settings at least, but they've never been its main selling point, and they keep changing the default setting every edition. I'm not sure that's why it and its derivatives are the best selling games.

Touche. I cannot argue against that. Maybe I'll get back to you after I pull my foot out of my mouth.

Nobody can touch D&D in name recognition. People ask me - what's RuneQuest and my default answer is - it's like D&D, only grittier. Unless some tv show that hits big makes a big todo about some other tabletop rpg D&D has no chance of being dethroned. At least currently. Pale Puppy was huge in the 1990s riding the success of vampire books and movies, including The Crow.

Quote from: drayakir on July 15, 2022, 10:23:04 PM
Well, I mean I suppose you could have a percentile system that doesn't use a d100, but... I dunno. The problem with the d100 and the d20 that at a certain point your skill/stat doesn't matter. If the target number is 13, and you're at +6, you have very good odds of it, but there's still a decently high chance that you will fail. More, you still run the risk of failing really easy tasks that somebody at your skill level has no business failing. That's why I prefer bell curve stuff, since that distribution is more like a realistic skill distribution.

One thing I like about expressing odds as a percentage is it's a lot easier to highlight the severe analytical defects in what you're saying. Which I think is important because a lot of gamers would agree with you. And it's straight up incorrect.

Take GURPS. There you have the iconic 3d6 bell curve that gets gamers rocks off. It's simple. Uses dice that's familiar even to the normies. They can be added up quickly. And it's high enough resolution that the probability distribution actually looks like a pretty damn sexy bell curve. Nothing but great things to say about it.

How does that work in practice. Well, my guy as 12 Dex and a +3 in Stabbing Sword skill. So I need a 15 or under to hit. That's roughly a 95% (rounding to the nearest integer) chance to hit. Got it. Switch systems.

Now I've got my Lejendary Adventure Avatar with 75 Weapons Ability, and the Stabbing Sword has a Precision bonus of 20. That's roughly a 95% chance to hit. Same thing. Because "swingy" is made up nonsense when your answering a question of "Did you do what you set out to do?" Either you do or you don't. And the probability that you do always boils down to a percentage.

I know what you're saying. But muh modifiers!

So now GURPS man is going for the coveted called shot through the eye socket to the brain, bypassing the natural armor of the skull, for -10 to hit. Now he needs 5 or under. Drops the probability to 5%.

LA guy, not to be outdone, goes for the same shot. Aimed attack means -20 to hit. And then to bypass armor requires getting a special success--rolling under 1/10 the probability. So 95 - 20 = 75, so you have to roll 7 or less. 7%. Not really a huge difference.

And yeah, I know there's someone somewhere thinking "Ackchyually 7 hits in 100 is 40% more hits than 5 in 100." But when there's no frame of reference to say which is more correct we are in fact operating within the margin of noise. It's clearly a similar order of magnitude in the adjustments.


The trick that gets pulled in these sorts of discussions is every argument you can make is hypothetical. As such, it makes assumptions that usually are not applicable to an actual play situation. That's why I cite specific rules from specific systems. It's a waste of time to speak in generalities like this type of mechanic does this, but that other type of mechanic does that.

If you're talking about a situation that's relevant to the game, and if the game was play-tested, I have to think the problem arose at some point, was addressed, and is not an actual problem. Maybe some games weren't as rigorously tested and put together as others. An example of a bad game is just that--an example of a bad game. Not evidence of a bad mechanic.

Quote from: Jason Coplen on July 15, 2022, 09:53:37 PM
Settings is my guess. Outside CoC what cool setting do they have? None. Sure, Glorantha is neat, but definitely not everyone's cup of Joe. That and there's no really good magic systems.

Well, Eclipse Phase has an interesting enough setting, but it's not to everyone's liking.

Quote from: HappyDaze on July 15, 2022, 11:35:31 PM

Quote from: Jason Coplen on July 15, 2022, 09:53:37 PM
Settings is my guess. Outside CoC what cool setting do they have? None. Sure, Glorantha is neat, but definitely not everyone's cup of Joe. That and there's no really good magic systems.

Well, Eclipse Phase has an interesting enough setting, but it's not to everyone's liking.

I've never looked at it. I'm ignorant as Hell when it comes to the game, except I know it's SF.

Percentages are too tangible and a given percentage may not feel right even if accurate. +1 on a d20 feels better that +5% on d100% to most people. 5% chance of failing catastrophically at a mundane time sensitive task is absurd but a 1 on a d20 is accepted.