(Editorial note) I have removed all the various experiments that lead to what is below. They may have had some passing interest to people into statistical math, but they cluttered the page and were confusing. I just left the finished product below.
As I am trying to keep this short I have omitted specific examples, but should any be desired, just drop me a line in the comments.
The following is a 3d6 roll over system for CS games.
I love D&D. I love the Cypher System, I love retro games of all sorts. I hate a d20 resolution mechanic. As most you probably know the d20 mechanic is essentially a random success generator with theoretical 5% increments of success for every number. So if you have to roll a 15 or better to hit you have 25% chance of success. Statistically that really only works if you roll the d20 an infinite number of times. Every finite roll has the same chance of rolling a 1 as a 20. In some game design this is called "swingy". It can add both excitement and frustration to any scenario because every time you let the dice roll you have no clue what will happen.
For some players though, myself included, this will frequently lead what should be highly competent characters to looking like complete morons when the can't seem to roll over a 4. The solution to this is to convert the primary die roll away from a swingy pass fail binary d20 roll, to an alternate system that works on a curve. Personally I like 3d6. A 2d roll is still fairly swingy. A 4d roll pulls hard towards the center results. The perfect in between is 3d6.
Enough theory; lets check out the system.
Level - Standard Target Number -Chance of Failure- TN (or Passing Threshold) on 3d6 roll over
1- 3 - 10% - 6
2 - 6 - 25% - 8
3 - 9 - 40% - 9
4 - 12 - 55% - 11
5 - 15 - 70%- 13
6 -18 - 80%- 14
Difficulties reduced, by assets, skills, and effort as per usual.
Levels 7-10 are still above normal human ability without the aid of Skills, Assets, or Effort
What is above is a fully functional binary system, but what if we make the value rolled of higher importance.
Degrees of success.
While rolling the number indicated above will create an adequate success for the task, for every point over ,up to 4, we will increase the effectiveness of the roll.
Passing Threshold (PT) = minimal listed success
PT+PT1= +1 numerical result
PT+PT2= +2 numerical result + minor effect
PT+PT3= +3 numerical result + minor effect
PT+PT4= +4 numerical result + major effect
No further bonuses or effects past PT+4
Rolls 3-4 invoke a GM Intrusion (Optional rule: PC gains +1 xp, but cannot cancel the effect by use of xp.)
Rolls of 17-18 allow for a player intrusion (in addition to any bonus given for overcoming the Passing Threshold)
Degree of failure consequences (Optional for solo play).
PT-PT1= Simple failure, no consequences.
PT-PT2= +1 numerical result favoring opposition.
PT-PT3= +2 numerical result favoring opposition + minor negative effect
Pt -PT4= +3 numerical result favoring opposition + Major effect (and optionally +1xp to PC).
In the system above hitting high rolls may seem more difficult than on a 20, so I highly encourage using terrain, equipment, effort, and player intrusions to give you the leg up to face more difficult challenges, by easing the Level. On the flip side, even beginning adventurers will be able to have very strong success against low Level oppositions. This is in favor with the idea of PC competency that is a corner stone of the Cypher System ideology.
W.D.
