aka "our d3 are different, we are so special"
Used for FUDGE and thus FATE rpg games. The bell-curve is pretty steep -- 2/3 of the time you're gonna roll -1, 0 or +1. Maybe this is supposed to get random chance out of the rpg without actually taking our candy away. The odds of rolling a "critical" of +4 is 1/81, or four times less likely than rolling a nat 20.
Where to buy
If you have to buy weird dice just to play a supposedly simple system, you have failed at life and should immediately swallow the Fudge dice in hopes of choking to death.
Take a d6 and a sharpie, draw a line on the 1 & 2 faces, an X on the 3 & 5 faces, and a square on the 4 & 6 faces (b). There you go: a die with -,0,+ on it. Now roll four of them to get a result from -4 to +4.
Or do it old school, with 1,2 = 1 ; 3,4 = 2 ; 5,6 = 3 and subtract 8 (that's 4d3 - 8). Be a man.
Some people are damn impatient and just roll a positive d6 and a negative d6, subtract one from the other, and treat -5 or +5 as 0. Now rolling a critical +4 becomes a 5% chance, same as rolling a natural 20, just like God intended. Similar to the Delta-6 method.
Feng Shui, a game which predates both Fudge dice and the systems which use them, made use of this method, though counted -5 and +5 as possible results and had a "something unusual happens" rule for boxcars.
- Mathfags do their stats homework about dF and tarot cards and junk.