I've come to realize that there are a lot of ways to generate different trends with dice. This is because I think about dice a lot. I walk around with a couple in my pocket. I fall asleep with dice in my bed. Once I drank too much at a party and vomited, and that was like, 30-40% dice. I think I rolled a 23.

Anyway, here's a diminishing return system for skills.

**The S Sys**

**tem**

**Roll two dice and**

**subtract**the smaller number from the bigger number. If this resultant number is equal to or smaller than the skill/stat/whatever, the attempt succeeds.

The shorthand for this is sX, where X is the die size. (Like d6 . . . s6, s8, etc)

Here's a couple examples of an s6 roll against a Pick Pocket skill of 1.

Rolled: 3, 4

3 - 4 = 1

1 is equal to (Pick Pocket) 1, so the attempt succeeds.

Rolled: 6, 3

6 - 3 = 3

3 is greater than (Pick Pocket) 1, so the attempt fails.

There are two huge advantages here:

1. Untrained (Score of 0) still has a chance to succeed (if both dice show the same number). With a d6, this is about a 17% chance.

2. There are diminishing returns as you invest points into this skill. That is, each point you put into the skill causes the % of success to increase by a smaller amount. But since reproducibility and confidence are so important, players will still want to invest in skills, even at higher ranks.

Let's look at some probabilities.

**s6 Probabilities**

Rank | % Exact Roll | % Success |
---|---|---|

0 | 17% | 17% |

1 | 28% | 45% |

2 | 22% | 67% |

3 | 17% | 84% |

4 | 11% | 95% |

5 | 5% | 100% |

So you can see, that even if a player has NO ranks in a skill, they still have a 17% chance to successfully attempt a skill (assuming you let them). But that first point increases their chance of success to a whopping 45%! Every point after the first one gives diminishing returns.

Is 17% too high for you? Do you want a finer graduation between Unskilled and Masterful? Use a bigger die. Rolling s8, s10, or s12 will all give you more discrete steps, while preserving a simple mechanic and giving diminishing returns.

In practice (and I have been practicing) this is dang fast.

And if you want to adjust difficulty, you can modulate the ranks by +/- 1 or 2.

Just for fun, here's the table for an s10 roll.

**s10 Probabilities**Rank | % Exact Roll | % Success |
---|---|---|

0 | 10% | 10% |

1 | 18% | 28% |

2 | 16% | 44% |

3 | 14% | 58% |

4 | 12% | 70% |

5 | 10% | 80% |

6 | 8% | 88% |

7 | 6% | 94% |

8 | 4% | 98% |

9 | 2% | 100% |

Ain't it cute?

If you roll the worst possible result (like a 1 and a 6 on a s6 roll), something bad happens. This is pretty rare.

If you roll doubles, and the number shown is equal-to-or-less-than your skill rating, you get a critical success, and good things happen. So if you have Skill 4 and roll double 3s, thats a critical success. Obviously, this means that you can never get a critical success if you have no skill in something.

The advantage of this is that critical failures will always be a threat no matter how skilled you are, while critical successes become more likely as you become more skilled.

Here are the s6 and s10 curves on anydice.com:

http://anydice.com/program/2d7b

**Critical Failures and Success**If you roll the worst possible result (like a 1 and a 6 on a s6 roll), something bad happens. This is pretty rare.

If you roll doubles, and the number shown is equal-to-or-less-than your skill rating, you get a critical success, and good things happen. So if you have Skill 4 and roll double 3s, thats a critical success. Obviously, this means that you can never get a critical success if you have no skill in something.

The advantage of this is that critical failures will always be a threat no matter how skilled you are, while critical successes become more likely as you become more skilled.

**And. . .**Here are the s6 and s10 curves on anydice.com:

http://anydice.com/program/2d7b

I can think of a couple of ways to rejigger it to apply to stat checks, too.

I like this. I could see using it for something. If I did, would you sue me?

ReplyDeleteThis looks pretty elegant! I hope you'll expand on it.

ReplyDeleteFor the same odds, it simplifies to 6 - d6 and 10 - d10. Making it into ability checks could be 20 - d20 vs stat.

ReplyDeleteI really like this system, very elegant.

actually, if you do 20 - 2d10 vs. stat, I think it works out better:

Deletehttp://anydice.com/program/2d8b

This think this is really cool. Thanks for posting it.

Doesn't this flatten out the odds and get rid of the diminishing returns?

DeleteAs a guy who played TORG for a few years, I have seen plenty of systems and ways of rolling.

ReplyDeleteIn TORG you have a success scale that gives you a bonus or malus on your skill level and you check vs the difficulty of the task. Rolling a 11 give a bonus of 0 while rolling a 1 gives a -10 and rolling 20 gives +5 and reroll and +1 for every +5 worth of your roll. You reroll all 10s and 20s.

I did a similar one with d6s where you reroll 1s and 6s