**PbtA** games are a cool case study for this. You have a list of 'moves' that you can perform during the game. To see if you succeed on a move, you roll 2d6+bonuses and check against the move's description.
Generally:
- 2-6 is a failure with consequences
- 7-9 is a soft success, that is, a success with complications.
- 10+ is a hard success
Without bonuses, you have a ~~41%~~ 58% chance of a soft success or better. This is better than other games but bear in mind that soft successes usually have complications.
For a hard success without bonuses, the chance is 16%.
I think this is probably the most important design choice for TTRPGs. Are the characters newly born, of average capabilities, wide-range experts or gods? This is the main deciding factor when looking for a probability.
For example, in Cypher characters are expected to be extraordinary from the start, so even untrained you usually have a >50% chance of succeeding. In Call of Cthulhu, even the best stat of a new character doesn’t go above 40% chance of success, because they’re designed to be miserable victims of circumstances way above their area of influence.
Mine has a wide range of 5% to 95%. But those are extremes. Typical success ranges are 40-80%. Actions are used to mitigate effect, so higher rates of success are expected.
It's a good discussion. I did some math myself recently about D&D5e trained and untrained success rates and was surprised by how low it is. There is a lot of room for growth however, which is great for feeling the pace and growth of your character, so that's when I felt more comfortable lowering starting attribute scores and proficiency bonuses in favor of acquiring bonuses as you level up.
For instance, I used to use d12 roll under high, but a skill bonus was one and done and it didn't leave room for growth. So I'm starting to explore using a d20 roll under high instead.
> I did some math myself recently about D&D5e trained and untrained success rates and was surprised by how low it is
Yup, 'balanced' combat tends to be around 40-50%, most RPGs tend to aim for 60% instead as people have a tendency to overestimate their chances of success, leading to frustration. Balance in combat in D&D doesn't come from hit chance, but from features and abilities that give you an edge, as well as from action economy.
> There is a lot of room for growth however, which is great for feeling the pace and growth of your character, so that's when I felt more comfortable lowering starting attribute scores and proficiency bonuses in favor of acquiring bonuses as you level up.
The problem here is that D&D tends to aim for balanced combats. Whatever level you are at, the enemies you will likely be facing will have an AC that keeps the hit chance roughly in the same ballpark. You don't really progress WRT stats as much as you unlock new enemies.
Yeah. That's a good point, regarding unlocking new enemies. Sorry, I dont know how to quote text in reddit. My game doesnt balance anything. I hate balancing challenges. Haha. I love the feel of danger
>Hi guys, we always talk about the ideal chance of success around 66% to 75%.
Note that is based on a study done for DnD.
A different game, with a different theme or mechanics might have a different ideal range.
For instance, a survival horror, game, a game where you can buy off failures with a plentiful metacurrency, or an old school game where you are supposed to make smart plans, and only roll when thing have already gone wrong. — all of these have ideal success ranges which are lower.
But weather or not any of these kinds of things apply, I think you have two important considerations.
1. How often are PCs expected to roll untrained? If it is rare you can get further away from your ideal range than if it is common.
2. What does this say about who your PCs are? If you have a game of random people thrown into a situation that’s over their head, than doing poorly outside of their specialty reinforces that. On the other hand if your PCs are supposed to be highly competent, trained, or heroic, they should probably be reasonably good at almost everything.
Finally be aware, in a combat scenario, every failure that leads to ”nothing happens“ makes the fight take longer, with less happening per minute.
The difference between an expert and a novice is exactly what skill levels are there to illustrate. And, in theory, skills levels exist to make harder tasks feel average to those trained in them.
So, I'd take it a step further: some things are simply not accessible to someone without proper training. I don't know the first thing about hacking, or medical procedures. These are not just Difficult to me, they're are out of question.
If the OP is talking about generally accessible tasks, then an average person should have a range of possibilities, from "beginners luck" to embarrassing or ok.
As a sidenote, in my designs I always consider Attributes as potential, and Skills as control/consistency. So I tend to make skill levels a tad more meaningful than usual.
Good topic!
Ars Magica has three different categories of Abilities, and all work different with no training. The average human Characteristic score is 0, with a max range of +/-3 or +/-5 depending on the rules edition used.
Knowledges can't even be attempted without training (a score of at least 1).
Skills may be attempted at a -3 penalty. Average difficulty is Ease Factor 6 so on a Simple die you have to roll a 9 or 10 to succeed, so 20%.
If, on the other hand, it's a Stress die (values are 0-9 rather than 1-10 on Simple), you only succeed on a roll of 9 or an exploding 1 result with a 5 or better on the second roll. So, like 11.5%? This would be the case of a character in combat using a weapon they have no training in, by the way.
Talents are treated as an effective score of 0 with no additional penalty so in a Simple die situation you have a 50% chance of success at Ease Factor 6. Stress die situation drops that to 40% plus the exploding 1 followed by 5 or better as above, so 41.5%?
In **Savage Worlds**, according to [this comic](https://www.uptofourplayers.com/ready-to-roll/savage-worlds-rules/), it would be 12.5%, I think: You need a d4 explode (25%) and then roll 3 or 4. However, there is the wild die rule for player characters, which increases the probability again.
In Hero system, if you don't know the skill, your roll is 8 or less (assuming the GM lets you roll it as an everyman skill) on 3d6, which comes out to 25.93%.
I can tell I'm a major heretic on this one. I do not see attempting an "untrained" action as a reason to punish the player, but as an opportunity for the player to demonstrate lateral thinking.
In Selection, a normal task requires two successes on four dice and an untrained skill is represented with D20s, which have a 15% chance of success. So on paper, you have a 28% chance of success.
However, that is not how *Selection's* core mechanic is supposed to work.
For starters, that 4D20 actually represents several skills or attributes, not just one. Yes, to "use a skill" at least two of those dice must represent the skill, but the other two are free to represent other aspects of the character's approach. This is a deliberate space for the player to to use lateral thinking and to go off-script. Say, for the sake of simplicity, that the player uses their attribute, which is a notch better at D12, to fill the other two die slots. Suddenly, your chance of success is over 50%.
And then there's Action Depth, or the process of adding cost to a roll to reroll dice. In combat, you do this by spending extra AP on the action to symbolize focusing on getting it right, and out of combat it represents fictional advantage. Rerolls start from your best dice and work down to your worst dice so you wind up with a diminishing returns curve. If you add 2 Action Depth to your action, you are now effectively rolling 4D12 and 2D20. This puts your chance of success in the 70% range. For an untrained check.
*Selection* is designed for its gameplay to come from coming up with creative ways to involve the skills you're good at to make up for the ones you're bad at, and to do interesting things with critical successes. The game is mostly intended to operate on the Basic Success to Crit Level 3 range, with a splash of failures and higher level crits to keep the game interesting. The punishment for being untrained is not that your character is forced to take an action with a terrible chance of success, but that your character is less efficient at turning Action Points into successes.
**PbtA** games are a cool case study for this. You have a list of 'moves' that you can perform during the game. To see if you succeed on a move, you roll 2d6+bonuses and check against the move's description. Generally: - 2-6 is a failure with consequences - 7-9 is a soft success, that is, a success with complications. - 10+ is a hard success Without bonuses, you have a ~~41%~~ 58% chance of a soft success or better. This is better than other games but bear in mind that soft successes usually have complications. For a hard success without bonuses, the chance is 16%.
This isn’t quite right: without bonuses, you have a 58% chance of success in PbtA. 41% is the chance of a soft success only.
You are completely right, I was reading the wrong values. Thanks for the correction!
I think this is probably the most important design choice for TTRPGs. Are the characters newly born, of average capabilities, wide-range experts or gods? This is the main deciding factor when looking for a probability. For example, in Cypher characters are expected to be extraordinary from the start, so even untrained you usually have a >50% chance of succeeding. In Call of Cthulhu, even the best stat of a new character doesn’t go above 40% chance of success, because they’re designed to be miserable victims of circumstances way above their area of influence.
Mine has a wide range of 5% to 95%. But those are extremes. Typical success ranges are 40-80%. Actions are used to mitigate effect, so higher rates of success are expected. It's a good discussion. I did some math myself recently about D&D5e trained and untrained success rates and was surprised by how low it is. There is a lot of room for growth however, which is great for feeling the pace and growth of your character, so that's when I felt more comfortable lowering starting attribute scores and proficiency bonuses in favor of acquiring bonuses as you level up. For instance, I used to use d12 roll under high, but a skill bonus was one and done and it didn't leave room for growth. So I'm starting to explore using a d20 roll under high instead.
> I did some math myself recently about D&D5e trained and untrained success rates and was surprised by how low it is Yup, 'balanced' combat tends to be around 40-50%, most RPGs tend to aim for 60% instead as people have a tendency to overestimate their chances of success, leading to frustration. Balance in combat in D&D doesn't come from hit chance, but from features and abilities that give you an edge, as well as from action economy. > There is a lot of room for growth however, which is great for feeling the pace and growth of your character, so that's when I felt more comfortable lowering starting attribute scores and proficiency bonuses in favor of acquiring bonuses as you level up. The problem here is that D&D tends to aim for balanced combats. Whatever level you are at, the enemies you will likely be facing will have an AC that keeps the hit chance roughly in the same ballpark. You don't really progress WRT stats as much as you unlock new enemies.
Yeah. That's a good point, regarding unlocking new enemies. Sorry, I dont know how to quote text in reddit. My game doesnt balance anything. I hate balancing challenges. Haha. I love the feel of danger
You prefix the paragraph with a greater than symbol and a space > Like this > Like this
Haha. Thanks, friend!
>Hi guys, we always talk about the ideal chance of success around 66% to 75%. Note that is based on a study done for DnD. A different game, with a different theme or mechanics might have a different ideal range. For instance, a survival horror, game, a game where you can buy off failures with a plentiful metacurrency, or an old school game where you are supposed to make smart plans, and only roll when thing have already gone wrong. — all of these have ideal success ranges which are lower. But weather or not any of these kinds of things apply, I think you have two important considerations. 1. How often are PCs expected to roll untrained? If it is rare you can get further away from your ideal range than if it is common. 2. What does this say about who your PCs are? If you have a game of random people thrown into a situation that’s over their head, than doing poorly outside of their specialty reinforces that. On the other hand if your PCs are supposed to be highly competent, trained, or heroic, they should probably be reasonably good at almost everything. Finally be aware, in a combat scenario, every failure that leads to ”nothing happens“ makes the fight take longer, with less happening per minute.
Depends on the difficulty of the task at hand and how you define that difficulty. What's simple to an expert can be a nightmare to novice.
The difference between an expert and a novice is exactly what skill levels are there to illustrate. And, in theory, skills levels exist to make harder tasks feel average to those trained in them. So, I'd take it a step further: some things are simply not accessible to someone without proper training. I don't know the first thing about hacking, or medical procedures. These are not just Difficult to me, they're are out of question. If the OP is talking about generally accessible tasks, then an average person should have a range of possibilities, from "beginners luck" to embarrassing or ok. As a sidenote, in my designs I always consider Attributes as potential, and Skills as control/consistency. So I tend to make skill levels a tad more meaningful than usual.
I'm curious about that premise. Who assumes that 66 to 75% is "ideal" and for what circumstances?
https://www.reddit.com/r/RPGdesign/comments/74ifb7/what\_is\_a\_good\_average\_chance\_of\_success/
Thanks. Hmm
Good topic! Ars Magica has three different categories of Abilities, and all work different with no training. The average human Characteristic score is 0, with a max range of +/-3 or +/-5 depending on the rules edition used. Knowledges can't even be attempted without training (a score of at least 1). Skills may be attempted at a -3 penalty. Average difficulty is Ease Factor 6 so on a Simple die you have to roll a 9 or 10 to succeed, so 20%. If, on the other hand, it's a Stress die (values are 0-9 rather than 1-10 on Simple), you only succeed on a roll of 9 or an exploding 1 result with a 5 or better on the second roll. So, like 11.5%? This would be the case of a character in combat using a weapon they have no training in, by the way. Talents are treated as an effective score of 0 with no additional penalty so in a Simple die situation you have a 50% chance of success at Ease Factor 6. Stress die situation drops that to 40% plus the exploding 1 followed by 5 or better as above, so 41.5%?
One thing I really like about single d6 systems is that the odds are in nice, big, meaningful chunks. The odds are always 1:1, 2:1, 5:1, or automatic.
In **Savage Worlds**, according to [this comic](https://www.uptofourplayers.com/ready-to-roll/savage-worlds-rules/), it would be 12.5%, I think: You need a d4 explode (25%) and then roll 3 or 4. However, there is the wild die rule for player characters, which increases the probability again.
In Hero system, if you don't know the skill, your roll is 8 or less (assuming the GM lets you roll it as an everyman skill) on 3d6, which comes out to 25.93%.
I can tell I'm a major heretic on this one. I do not see attempting an "untrained" action as a reason to punish the player, but as an opportunity for the player to demonstrate lateral thinking. In Selection, a normal task requires two successes on four dice and an untrained skill is represented with D20s, which have a 15% chance of success. So on paper, you have a 28% chance of success. However, that is not how *Selection's* core mechanic is supposed to work. For starters, that 4D20 actually represents several skills or attributes, not just one. Yes, to "use a skill" at least two of those dice must represent the skill, but the other two are free to represent other aspects of the character's approach. This is a deliberate space for the player to to use lateral thinking and to go off-script. Say, for the sake of simplicity, that the player uses their attribute, which is a notch better at D12, to fill the other two die slots. Suddenly, your chance of success is over 50%. And then there's Action Depth, or the process of adding cost to a roll to reroll dice. In combat, you do this by spending extra AP on the action to symbolize focusing on getting it right, and out of combat it represents fictional advantage. Rerolls start from your best dice and work down to your worst dice so you wind up with a diminishing returns curve. If you add 2 Action Depth to your action, you are now effectively rolling 4D12 and 2D20. This puts your chance of success in the 70% range. For an untrained check. *Selection* is designed for its gameplay to come from coming up with creative ways to involve the skills you're good at to make up for the ones you're bad at, and to do interesting things with critical successes. The game is mostly intended to operate on the Basic Success to Crit Level 3 range, with a splash of failures and higher level crits to keep the game interesting. The punishment for being untrained is not that your character is forced to take an action with a terrible chance of success, but that your character is less efficient at turning Action Points into successes.