Intuitive Difficulty RPG/Game Dice (D7 on D20)

Intuitive Difficulty Dice

Each time you need to roll "one more than before", it becomes more difficult by the same factor (140%), approximately.

Great for sensible difficulty increases in RPGs and Wargames that use a lot of Die Modifiers (+/- DMs)

Can be used in game design to eliminate complicated rules, extra tables, and mental arithmetics.

Includes FreeCAD source files in case you'd like to modify the design.

Print instructions

Category: Dice Summary

Intuitive Difficulty Dice

Each time you need to roll "one more than before", it becomes more difficult by the same factor (140%), approximately.

Great for sensible difficulty increases in RPGs and Wargames that use a lot of Die Modifiers (+/- DMs)

Can be used in game design to eliminate complicated rules, extra tables, and mental arithmetics.

Includes FreeCAD source files in case you'd like to modify the design.

How I Designed This

Distribution

The Intuitive Difficulty Dice feature the following distribution:

• 2: 4x
• 3: 3x
• 4: 2x
• 5: 2x
• 6: 1x

• 7: 1x
  The chances of achieving a certain number or higher are:

• 1: 100% :-)

• 2: 70%
• 3: 45%
• 4: 25%
• 5: 15%
• 6: 10%
• 7: 5x
  The chances of success for each increase of +1 are reduced to the following percentage of the unmodified chances:

1 + 1: 70% 2 + 1: 71%
3 + 1: 70% 4 + 1: 60%
5 + 1: 67% 6 + 1: 50%

So the die is not perfect, due to only having a finite number of faces, but I think it's pretty good :-)

History

I came up with this die out of frustration with convention die roll modification systems back in the late 1980s, calling it the "logarithmic die". Attempts to build such a die by modifying existing dies resulted in ugly, stickered, poorly-rolling creations so that I gave up on the concept.

My hopes that someone else would have the same idea and come up with a nice mass-produced die of this type unfortunately never materialized.

With the advent 3D printing, it suddenly became easy to have good-looking and accurate dice printed, so I designed these dice in FreeCAD. Yay!

Fairness

Obviously, the more accurate the print, the better the chances that the die rolls are distributed truly randomly. I had my dice printed by a service provider using a laser-sintering process that gave quite satisfactory accuracy.

I measured the dimensions with a micrometer screw, and the distance between each two opposite faces varied between 18.16 mm and 18.37 mm in the extremes, which I'm quite happy with.

The weight distribution of the dice is even in spite of the use of "pips" (holes) to indicate the values, as the diameter and depth of the holes is varied to ensure that the total volume of the pips is the same on each side.