I've started GM'ing our group's first Fudge game after 20+ years playing GURPS. The change was made because our games were becoming less and less number crunchy and more and more story driven.

However ...

After about a dozen play sessions there is some dissatisfaction. One of the key areas is that the 4DF seems to swamp the skill. A character with Fighting at Great rolls -2 and gets beaten by an NPC mook rolling +1 on a Good skill. The feeling is that 3D6 has less effect on a 3 to 18 Skill level in GURPS, so a good fighter remains good more of the time ... but is this just perception? Could it be GM style, in which case what symptoms should I be looking for? A player suggestion is reducing to 3DF, just to ameliorate the dice effect. Has anyone tried that and if so with what result?

(We have a number (too many!) mathematicians at the table so any discussion on probability spirals out of control in seconds: I'm trying to avoid that!)

As another footnote - I'm looking at changing/tuning again and going in the FATE direction: the free-form nature of Fudge seems to be one step too far.

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    \$\begingroup\$ Rolling a -2 has less than a 10% chance of happening; the opponent rolling a +1 at the same time brings the odds down to about 3%. That kind of thing shouldn't come up very often; if your table is full of mathematics they should be aware that this is a very rare event. \$\endgroup\$
    – Erik
    Sep 8, 2016 at 10:20
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    \$\begingroup\$ rolling -2 or less has precisely 5/27 chance of happening (approximately 18.5%), rolling +1 or more has 31/81 (38%), so the odds are about 7%: not such a very rare event. \$\endgroup\$ Sep 8, 2016 at 11:42
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    \$\begingroup\$ @AnneAunyme: you're right, I messed up my graph-reading skills. Still; a somewhat rare event. Comparable to throwing a 1 on a d20, or a 6 or less on a 3d6. \$\endgroup\$
    – Erik
    Sep 8, 2016 at 13:09
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    \$\begingroup\$ actually what matters is the probability that "the difference between the two rolls it at least 3", and it is about 14%. It's more like "rolling 3 or less on a D20" \$\endgroup\$ Sep 8, 2016 at 15:32
  • \$\begingroup\$ @Erik I think that 14% was the value given to me when the mathmos came back to the mundane world of numbers! (IANAM) \$\endgroup\$ Sep 8, 2016 at 15:42

4 Answers 4


Actually the problem is the opposite of what you stated. A +1 bonus with 4DF when you are dealing with opposed rolls has a far greater impact than a +1 with 3d6 and 1d20.

To see this, take a look at this anydice At Least graph. You will see that the first set of result has a result of 0 occurring at least 61.73 percent of the time. And +1 occurs at least 38.27 percent.

At +1 to the die roll then +1 occurs at least 61.73 percent of the time as you can see in the second set of results. This is an improvement of 23 percent!

I first noticed this when I was playing a Fudge based RPG that I wrote. It doesn't show up right away but as more session were run it was obvious that a +1 bonus was a big deal in a way it isn't with other systems.

I wrote a combat simulator to check this and sure enough when I give one of the fighter a +1 skill the odds shifted dramatically over 10,000 fighters. The reason it doesn't show up right away because as you noted the result of a fudge die is from -4 to +4. Which can and does swamp a +1 or even a +2 difference in ability on an opposed roll.

Plus we are talking about tabletop roleplaying where the character can find themselves in a variety of circumstances that make the fights more than just two guys wacking away at each other like in my simulation.

To sum this up, what you are seeing is just bad luck on your group's part. Over time the frustration that build when dealing with opponents that are more skilled in opposed situation will be a far bigger issue than the range of result from the Fudge Dice.

As a final note, note the shape of the bell curve of 4dF on anydice versus that of a 3d6. Fudge dice have a more dramatic peak in the middle. This is what causes the issues that I been seeing.


It's been my experience that the curve on 4dF is pretty much a sweet spot for "predictable unpredictability."

Because most of the time the raw dice come in between -1 and +1, even a +1 on a skill will frequently mean the difference between failure and success against an easy difficulty. A +4 means your character will hardly ever fail if they're not being actively opposed--thus often obviating a roll (see below).

On the other hand, it's possible that your group is rolling too often, with too little at stake for each roll. We use dice to introduce uncertainty to the equation, and that means dice rolling is a "sometimes" mechanic for these games. There are two basic reasons to use a mechanic in Fate: things aren't interesting, or you don't want to choose between two interesting things. Often the group will just go with the most interesting outcome and never let the dice hit the table. In those instances, often skill ranks get used as a measure of general competence rather than as a modifier to a roll: "You've got +4 in Fight to the goblin's +1, so you can just sucker punch him."

Now, you're playing Fudge and my experience has been in Fate. This is important because Fate has , which Fudge does not, and they totally change the scenario: fate points are a dramatic currency for players to effectively ignore the dice when it really matters, but they're a limited currency so the choice is truly significant. In some situations fate points get exchanged instead of dice getting rolled at all, and in others they're spent to improve rolls or re-roll. I suspect your group will appreciate that Fate makes RPGs less of a numbers game by adding a dramatic currency that keys off of scene elements.

With all of that said, your group has hit on a point I've been thinking about lately: when rolls are opposed the curve goes a little weird. The chance of extreme outliers is reduced, but the extremity of those outliers is dramatically increased. To this end, in my next Fate game I plan to use only player-facing dice and have all my NPCs act as if they always roll +0. I expect this will also improve my subpar fate point expenditure as a GM and better fuel the Fate economy.


That problem arises when the rolls are opposed and two sets of 4dF are rolled which is mathematically the same as someone rolling 8dF.

If someone was rolling unopposed with a 1-point skill, they would succeed¹ %62 of the time. Opposed, the same chance drops to %58 with the same 1-point skill advantage (the difference between raw skills)

Δ  Unopposed  Opposed
       (4dF)    (8dF)
—  —————————  ———————
0        38%      42%
1        62%      58%
2        81%      74%
3        94%      86%
4        99%      94%

So it does make a difference. And there is a simple solution if this annoys you. Just change the rules and have only the player roll in opposed actions, versus the opponent's raw skills. Then you get back to the same success probability as in the unopposed rolls, and the difference in skill makes somewhat more of an impact.

¹ By success, I consider rolling higher than your target/opponent. Equals are ties.


Getting a -2 has a 11.11% chance of happening while getting a +1 has a 23.46% chance of happening and that event had 2.61% chance of happening so your pal was basically unlucky

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