Why are skill challenges "broken"?

[two]

The main problem with skill challenges in 4e is that the entire design is flawed:

Skill challenges, as described in the DMG, output the ratio of successes to failures and compares that ratio to an effective threshold. Unfortunately, this means that the result is being normalized to the range 0 (no successes) to 1 (all successes): the spread around the most likely result goes as 1/sqrt(N) where N is the number of rolls. For largish (and it doesn't take that large) N, then, you have either virtually guaranteed success, virtually guaranteed failure or almost exactly 50% success WITH extreme sensitivity to small modifiers (a +/-1 on the DCs might take you from 50% success to 10/90% success). The extreme sensitivity to small modifiers is the core of what kills 4e's skill challenges.

Now let us take a better system (Stalker0's Obsidian system might be an example of what follows, I'm too lazy to relook it up). In this system, we work on an additive rule: the system outputs the total number of successes. Further, the range we compare the system to varies as sqrt(N). In the Obsidian system, this would mean that you expect a partial successes, and the width of the partial success range (total success-failure success numbers=constant*sqrt(N). Stalker0, if this isn't the case, it should be). What does this get us? Mainly the fact that the probability gradient is independent of N: our sensitivity to small modifiers does not depend on N. Under such a system, IF you correctly center everything (most individual rolls succeed near 50%, the expected success totals gives you the desired outcome, modifiers on individual rolls are +/- 4ish or less on a d20), the final success/failure probabilities will behave reasonably, NOT depending wildly on N.

In short, NO system based on success/failure ratios will either do well over a large range of N, or behave well for even moderate N. A good system using many rolls will need to have a total number of successes margin of error that scales as sqrt(N), however they choose to implement it.

So, finally, we want a system where:
(1) target number of successes T scales linearly with N, with the skill challenge difficulty delta T (as opposed to individual check difficulty) being a modifier on T that also scales with sqrt(N).
(2) success/failure/partial success windows that (when measured in successes) scale with sqrt(N).
(3) individual check success probability averaging near 50%, and modifiers around that number small (which keeps us in the linear response regime).

This post, which seems to have gone unnoticed, is actually one of the most sophisticated and interesting things I've ever read on EnWorld.

Thanks for posting.

 

[Spinachcat]

I have had zero problems with skill challenges in actual play. They have been terrific for exciting roleplay combo'd into using the hero's skills. The ingenuity of the players in using their skills and the back and forth roleplay with the GM during the challenges has been terrific. Far more roleplay that we ever had in 3e.

Skill challenges are certainly the most fun part of 4e for our groups. If all you are doing is calling out for skill rolls, that's not the point of the skill challenge. It's all about merging roleplay with skill rolls with defined win / lose stakes. This is the place for some great improv and player input into the storyline.

 

[Runestar]

Something has been bugging me for some time now.

What is it about the concept of skill challenges that apparently makes it so viable in 4e, but not in 3e? It is in essence just a series of skill checks. Given that skills still work the same for most part (you roll a d20 to beat a set DC), this would suggest that skill challenges are not so much of an improvement, but just an extra set of rules that simply happened to be introduced in 4e rather than 3.5 (possibly because they wanted more selling points to promote a new edition).

I mean, I have had scenarios in my 3e games which involved the entire party contributing with skill checks and other abilities. We just didn't have a fancy term for it, but the concept behind it seemed similar for most part.

 

[FireLance]

What is it about the concept of skill challenges that apparently makes it so viable in 4e, but not in 3e?

Generic skill challenges (as opposed to skill challenges that are tailored specifically to a particular party or character) are more viable in 4e than in 3e for the following reasons:

1. There are a smaller number of skills, so it is more likely that some, if not all, of the PCs will be trained in skills that either have obvious applications or which can be used to contribute with a little imagination.

2. The difference in ability between a trained character and an untrained character is generally lower in 4e than in 3e, so there is more scope to set skill check DCs that have a nontrivial chance of success or failure for both characters.

You could run 4e style skill challenges for 3e characters, but you have to be more mindful of the characters' actual abilities.

 

[Zelc]

If people can consistently hit DCs of 60 (Diplomacy) at single-digit levels, the skill challenge system doesn't work as well .

By the way, the Obsidian Skill challenge in a nutshell:
Your party needs to make X successes in 3 "rounds" of rolling (not round as in 6 seconds, but round as in everyone rolls once). X is determined by the difficulty of the challenge. There are partial successes and successes (and failures).

 

[Stormtalon]

Interesting. It seems I've interpreted it differently. "For skill checks: Increase DCs by 5" says to me that it applies to all skill checks. Or rather; I haven't read anything that says this is NOT the case for skill challenges.

Well, look at it this way. By requiring X successes before X/2 failures for an overall success, you're inherently increasing the difficulty of the situation by a large amount. Why, then, would you go in and add yet another layer of difficulty on top of it?

Additionally, the example they use in the DMG of applying the +5 increase is a one-off skill usage. While they could (and should) have clarified things by showing how to use the table for DCs for skill challenges, the fact that they explicitly went with a one-off as the example lends (to me) more weight that the +5 is not intended for challenges.

 

[Christian]

This is one of the reasons I prefer the existing "flawed" system to most explanations purported to "fix" it.

You've got to do this kind of hard math work to design a working system, D'Karr. The goal is that once you're done, the DM doesn't have to--the math is built-in.

 

[D'karr]

You've got to do this kind of hard math work to design a working system, D'Karr. The goal is that once you're done, the DM doesn't have to--the math is built-in.

Yes, and it is great that some are doing just that. My point is that providing a simple explanation to the DM's is what is needed. A post chock-full of jargon is just confusing to those not familiar with what the problem is to begin with. As a matter of fact, IMO, it is even more confusing and worse off than the "broken" system.

 

[starwed]

Kraydak[/URL]]In short, NO system based on success/failure ratios will either do well over a large range of N, or behave well for even moderate N. A good system using many rolls will need to have a total number of successes margin of error that scales as sqrt(N), however they choose to implement it.

This is the key point of Kraydak's post: it doesn't matter how you set the DCs, the system is fundamentally broken.

This is one of the reasons I prefer the existing "flawed" system to most explanations purported to "fix" it.

Way to ignore what is by far the most insightful post on this topic I've read to date. It's fair to say that you don't understand it, and ask for a "layman's explanation", but to dismiss it out of hand is outright foolish.

 

[Nail]

Yes, and it is great that some are doing just that. My point is that providing a simple explanation to the DM's is what is needed..

Okey dokey!

Here it is:

The Problem: Skill Challenges are more likely to fail than succeed at level-appropriate DCs. Paradoxically, they also get slightly *easier* if they are higher Complexity. This is RAW in the DMG. (You wanted "simple" so I'm omitting the math proof showing this is so.)

The Solution: Make the number of failures equal to the number of successes -- that is, 4 successes before 4 failures (instead of 2 failures). In addition, hand out +2 modifiers for "good role-playing/puzzle solving stuff". And finally, sometimes allow less skilled PCs to "aid another" the more skilled PCs. Do not allow this all the time.





That's it! Simple enough?