Simplification and Complexity: Task Resolution

Echelon, being derived primarily from the Revised System Reference Document, uses a d20-based task resolution system.

Pretty much all character-related actions that can pass or fail have the decision made with a single die roll:

d20 + modifiers >= Difficulty Class (DC)

This is about as simple as it gets, really.   A consistent mechanic and easily remembered.

Degrees of Success and Failure

Most of the base game runs pretty handily on a pass/fail mechanic. There a few places that consider degrees of success and failure, but not many. Off the top of my head,

  • Critical hits (natural 20 — sometimes lower — confirmed by a second attack roll);
  • Climb checks (fail by 5 or more points and you fall);
  • Craft checks (fail by 5 or more points and you spoil half the materials and have to pay for them again in order to continue).

There are also some skills and checks where you can modify the DC or adjust your roll for better or worse effect. I do not consider these ‘degrees of success’ because it is still pass/fail, you have just accepted some greater risk for potentially greater result.

Using Climb and Craft checks as a base, you have two degrees of failure: no progress made, and bad effect (falling or ruining materials respectively), based on how much below the DC you rolled. This can be extended for greater degrees of failure (fail a Craft check by 10 and you have ruined the work entirely, and must start over), and inverted for degrees of success (every five points you roll above the DC gives some greater effect such as faster speed climbing or more progress made toward completing the item you are crafting).

This requires that you roll, determine success or failure, then subtract the DC (or subtract from the DC) to determine degree of failure.

There are times in the course of any night’s drinking playing that subtraction itself becomes difficult, but thankfully there is an easier mechanism.

Degrees of Success by Examination

Instead of determining degree of success or failure by subtraction, look to the natural die roll. The lower the value on the die, the better the result (bigger success or smaller failure), and the higher the value on the die, the worse the result (smaller success or bigger failure).

I might divide the d20 natural values into the following ranges:

Roll Success Failure
1..5 Supreme Success Normal Failure
6..10 Great Success Improved Failure
11..15 Improved Success Great Failure
16..20 Normal Success Supreme Failure

Or, being Echelon where I like four-point ranges (and skill training gives a +4 bonus):

Roll Success Failure
1..4 Supreme Success Marginal Failure
5..8 Great Success Normal Failure
9..12 Improved Success Improved Failure
13..16 Normal Success Great Failure
17..20 Marginal Success Supreme Failure

‘Marginal Success’ is one where you almost completely succeed, but not quite. You did achieve your goal, but there may be something not quite ideal. You might suffer a minor (-2) penalty on the next related check or suffer some minor inconvenience or loss (you did clear the pit, but you dropped something).

‘Marginal Failure’ means you almost completely failed, but there is some means of salvage. You might gain a minor (+2) bonus on your next related check (you missed your opponent but are in a better position) or enjoy some minor convenience or gain (you didn’t clear the pit, but you did hit the edge and may climb out, or you cleared the bit but landed poorly and take a bit of damage, or you fell in the bit but find the nice thing the last person who tried this dropped).

Automatic Success and Failure

In many checks, 1 and 20 are special cases, where 20 always succeeds and 1 always fails. If you need a 20 to succeed, you will never succeed by more than 0. As such, it would be reasonable that this is the minimal success.

Roll Success Failure
1 Automatic, Marginal
2-7 Great Success Normal Failure
8-13 Improved Success Improved Failure
14-19 Normal success Great Failure
20 Automatic, Marginal

Why this Works

The chance of rolling a 20 when you need 15+ is 5%, as is the chance of rolling 15. The chance of rolling 19-20 when you need 14+ is 10%, as it the chance of rolling 14-15. The chance of rolling 18-20 when you need 13+ is 15%, as is the chance of rolling 13-15. I won’t demonstrate a proof here, but the pattern does hold true for other values and ranges.

Degrees of success by examination provides the same chance of each degree of achievable success (or failure) as by finding the difference, as long as the target DC is no more than 20 points away from the modifiers available.

Why This Won’t Work

People love the ‘natural 20 woohoo!’ feeling.

Closing Comments

Basic task resolution is just that: basic.  It is entirely serviceable, but many people like to see a little more differentiation in degrees of success.

To do that, the obvious mechanism is to compare the total check result against the Difficulty Class of the check.  Easily explained, but I find it annoying in practice because common cases, obvious success and obvious failure, still require a lot of work to be done.  Depending on the mental state (fatigue and inebriation) this could be more trouble than people are willing to do, and error prone.

Instead, going to an examination method allows the obvious success and failure cases to be handled very quickly using a standardized table.  The only time it is necessary to work out the exactly check result is when it is a borderline case… in which case the additional effort determines whether it is a greater success or greater failure.

This does take away from the “20 is always best!” idea, and I admit I’m not really excited about that because I like rolling natural 20s as much as the next guy.  I think in the end that if I want to include degrees of success in a convenient and functional way, I can live without “20 is always best!” pretty easily.

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9 Comments to "Simplification and Complexity: Task Resolution"

  1. November 7, 2012 - 1:52 am | Permalink

    So would a “great” success/failure replace the idea of a critical success/failure? I guess it would be impractical to use natural-1 and natural-20 for the latter at the same time as your above approach.

  2. David Lamb's Gravatar David Lamb
    November 7, 2012 - 2:11 pm | Permalink

    I must be brain-dead today because I don’t understand your “simpler” system at all. Don’t take this as a big deal, but it might mean you need to rethink how you explain it.

    I can see one minor objection, or maybe not an objection but an observation: you are assuming that the PCs are almost always facing on-level or near-level competition. Can’t my heroic fighter have fun carving his way through an army of wimps? “I succeed by 27 and kill three adjacent goblins in one blow”

    One more example of success degree: Knowledge rolls, with each +5 giving “one more piece of useful knowledge.”

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