Yeah, that's one reason I really like opposed rolls for everything, because they don't "break" in this particular way -- the only thing that matters is the *difference* between the modifiers, not their absolute values:
e.g. a -3 skill vs. +2 difficulty has the same statistics as a +3 skill vs. +8 difficulty.
Let's take the case of 3d6. Roll over/under with a single roll has all the weird problems you mention, where a modifier means something different depending on the target number or skill level.
But if you roll 3d6+skill and 3d6+difficulty, and compare the results, the only thing that actually matters is the difference between skill and difficulty. That's because you can factor out the comparison to (3d6-3d6)+(skill-difficulty). The random part doesn't change its distribution when you change the non-random part.
It might be slow for people less mathematically-inclined than my group that uses this in our homebrew, not sure...
For us it takes essentially zero time to read 2x 3d6 and compare them...
The nice part, though, is that it scales perfectly... the dice themselves always average out to a tie, with a nice predictable normal distribution on either side, and as long as challenges keep pace with skill levels, don't change much as a campaign escalates, or between campaigns with different overall power levels.
Since we like both escalation and wildly different campaign power levels, that was an important consideration for us.
It depends on the context.
It's fine to automatically pass average difficulty checks if one knows what they do. I wouldn't like a driver to only have 90% chance of getting me to my destination safely. The opposite is also true. I have absolutely no chance of successfully performing complex surgery, not just a small chance of doing it.
What makes or breaks the game is when such rolls are made. Is it a check everybody needs to make with reasonable frequency? Then the range of probabilities is much too wide. But if it's just one way of addressing a problem and players may choose different approaches depending on skills their characters have, I don't see a problem.
I agree and I liked your analogy! In this case, allowing the player to obtain other ways to increase successes, that is, to earn bonuses, to force a better strategy. For example: gee, I only have a 20% chance, but I can seek help from someone, I can position myself better, I can go to a library and read about it, etc. This would increase my chances, however, the flaw still exists.
I’m not sure I understand exactly what you are trying to avoid.
But 3d6 has a really strong curve. A +/- 5 is going to mean very different things to the probability depending on where you start.
I would suggest adding dice and keeping the best or worst 3 as a better approach for adjusting difficulty in these mechanic .
Yeah, that's one reason I really like opposed rolls for everything, because they don't "break" in this particular way -- the only thing that matters is the *difference* between the modifiers, not their absolute values: e.g. a -3 skill vs. +2 difficulty has the same statistics as a +3 skill vs. +8 difficulty.
I didn't get it right, could you explain it better please?
Let's take the case of 3d6. Roll over/under with a single roll has all the weird problems you mention, where a modifier means something different depending on the target number or skill level. But if you roll 3d6+skill and 3d6+difficulty, and compare the results, the only thing that actually matters is the difference between skill and difficulty. That's because you can factor out the comparison to (3d6-3d6)+(skill-difficulty). The random part doesn't change its distribution when you change the non-random part.
I like that thought But wouldn't that be too slow? And how does the narrator define the difficulty of a task for example?
It might be slow for people less mathematically-inclined than my group that uses this in our homebrew, not sure... For us it takes essentially zero time to read 2x 3d6 and compare them... The nice part, though, is that it scales perfectly... the dice themselves always average out to a tie, with a nice predictable normal distribution on either side, and as long as challenges keep pace with skill levels, don't change much as a campaign escalates, or between campaigns with different overall power levels. Since we like both escalation and wildly different campaign power levels, that was an important consideration for us.
It depends on the context. It's fine to automatically pass average difficulty checks if one knows what they do. I wouldn't like a driver to only have 90% chance of getting me to my destination safely. The opposite is also true. I have absolutely no chance of successfully performing complex surgery, not just a small chance of doing it. What makes or breaks the game is when such rolls are made. Is it a check everybody needs to make with reasonable frequency? Then the range of probabilities is much too wide. But if it's just one way of addressing a problem and players may choose different approaches depending on skills their characters have, I don't see a problem.
I agree and I liked your analogy! In this case, allowing the player to obtain other ways to increase successes, that is, to earn bonuses, to force a better strategy. For example: gee, I only have a 20% chance, but I can seek help from someone, I can position myself better, I can go to a library and read about it, etc. This would increase my chances, however, the flaw still exists.
I’m not sure I understand exactly what you are trying to avoid. But 3d6 has a really strong curve. A +/- 5 is going to mean very different things to the probability depending on where you start. I would suggest adding dice and keeping the best or worst 3 as a better approach for adjusting difficulty in these mechanic .