dn - dn

[Camelot]

What are some examples of a tabletop rpg that uses a dn - dn method of dice rolling? As in, to make a check you roll two dice of different colors (say, red and green). You add the green die to your stat and subtract the red die, getting an average of zero. Another way to achieve this is to roll both those dice and only add the lower number. If it's on the green die, it's positive; if it's on the red die, it's negative; and ties means zero.

So yeah, I'm trying to make my own game that uses this system but I'm having some trouble making a success/wound system that doesn't take forever to play out. I'd like to look at some other games that use this dice mechanic for comparison.

 

[jonesy]

There's a series of articles on dice at RPGnet, which might be useful:
Roll the Bones #3: Simple Rolling Methods - RPGnet

 

[Piratecat]

Feng Shui uses this. Your score is (Pos die - neg die + Skill). Sixes explode, and you reroll them, adding 6 and rerolling every time a 6 comes up; this lets you occasionally attain ludicrously high or low numbers. If your total score is 0 or lower, you fumble.

 

[darjr]

d4-d4 is one. I've never played it nor read it, only heard about it.

 

[Pbartender]

Feng Shui uses this.

That's the one I was trying to remember and couldn't.

 

[Piratecat]

Feng Shui's system has everything derived from this one roll - if this number tops their defense, you take the difference, add the weapon damage, and subtract their toughness to determine damage. Frankly, it's too much damn math on the fly.

I love the d6-d6 system, though. I can think of a few easy ways to speed it up.

 

[TarionzCousin]

Legends of Anglerre (FATE) uses this method.

So does Icons, IIRC.

 

[Stormonu]

I think Alternity does something like this (or maybe its dn + dx).

 

[Janx]

I gotta ask, to what end?

How is this method "better"?

it involves 2 dice, instead of one
it involves 2 mathematical operations instead of one

If I read you right, an example using d6's is:

stat + 1d6 - 1d6 >= target

I imagine the target is the same as the stat for a 50-50 chance

Compare that to:
stat + 1d5 >= target

In this scenario, the target for a 50-50 chance is probably stat + 3.5 (the die average) probably rounded.

This seems to be more work, for what seems to be the same end. In an opposed roll system, it might have value:

mystat + 1d6 >= yourstat + 1d6

here' both parties roll and thus each party only performs 1 math operation. A side effect is that one side gets a slight advantage in dealing with a tie, so as to avoid a stalemate (unless stalemate is a state you want to deal with)

There are folks who like different resolution systems. There are folks who like rolling dice. Mostly, I find they just make odds calculations harder, and make determining success harder. Making things harder to do is generally not a good goal.

So, what am I missing? What can this mechanic do that solves a problem?

 

[Relique du Madde]

ICONS essentially uses a 1d6-1d6 + (Modifier) vs Difficulty*

* The roll is modified by your attribute/power/skill rank and any misc. modifiers. If the roll is equal to or above the difficulty then you are successful. However, the degree of success depends on how much you beat the roll by.