OK, this is going to be the driest post I think I'll ever do, but it's a necessary eeeevil. Actually, no, it's not, it's real important that I get this right. Cause the one thing you do over and over again in RPGs is roll dice. It's gotta work right, it's gotta be fun, it's gotta have longevity and ease of play, it's gotta serve the setting well. So yeah. Important. And I'll be super grateful if you slog through this and let me know what you think. I'll buy you a beer for your thoughts.
So based on the ideas and comments from the first post about MUTANTOR's dice mechanic and extra input here (thanks everyone who commented) I've worked out 4 possible ways this system could work.
To recap the basic idea:
Roll three d6 dice, scratch the highest and lowest roll take the middle dice as your result. Equal or beat the difficulty to succeed.
The variations come from what happens when you roll doubles (two faces the same) or triples (three faces the same).
There are four options I've chosen to do this. And depending on which one I choose there's a pretty broad variety of results available. Here's a comparison, showing the number of times a result occurs using the different methods:
A comparison of the various readings of the MUTANTOR dice engine.
Note that for Options 2, 3 and 4, rolling double ones gives a result of 1, and triple ones gives a result of -1.
Option #1: Middle of 3d6 Baseline : Eliminate the highest and lowest die.
Number of times each face occurs out of 216 possible results.
So this first method is included more as a baseline for the other methods; rolling doubles or triples has no mechanical benefit, though they could still have bonuses elsewhere (every time you roll them you could gain special points elsewhere for example). I don't see this option as particularly exciting or noteworthy. More just for comparison.
Option #2: Middle of 3d6, Doubles +1, Triples +2 : Eliminate the highest and lowest die, add one to result if two faces, the same, add two to result if all three faces the same except snake eyes equals 1, and triple 1 equals -1. Number of times each result occurs out of 216 possible results.
So in this option, rolling doubles means you add 1 to the doubled face to get the result, and rolling triples means you add 2 to the tripled face to get the result. The results spread out a little from the baseline of Option #1; 66% of your results will be a 3, 4, or 5 which is pretty good for setting reasonable expectations on what you'll get when you roll, with the average most likely to be 4.
Option #3: Middle of 3d6, Doubles +2, Triples +3: Eliminate the highest and lowest die, add two to result if two faces are the same, add three to result if all three faces the same, except snake eyes equals 1, and triple 1 equals -1. Number of times each result occurs out of 216 possible results.
This is pretty similar to Option #2, but based on Zak's suggestion to make the doubles +2 and triples +3 for ease of remembering. It blows the results out a little bit, making higher scores a little easier to get, though the predictability is a little less: results of 3, 4, or 5 occur 58% of the time now.
Eliminate the highest and lowest die, double the result if two faces are the same, triple the result if all three faces the same, except snake eyes equals 1, and triple 1 equals -1. Number of times each result occurs out of 216 possible results.
I actually think this is the easiest variant to remember: roll doubles, double the result, roll triples, triple the result. It also produces the most unusual spread of results too. A little weird and lopsided, but not unusable either. It's the least predictable: only 51% of results will be 3, 4, or 5. So every second roll will produce something a little higher, possibly going as high as 18 (but having one 1 in 216 chance of occuring). It also has a few idiosincracities: you can never roll a 7 or 11 for example, and a 6 only seven times, but an 8 or a 10 fifteen times a piece.
So if you're looking at results as single numbers I don't think Option#4 is really workable.... BUT if you look at the results in bands, suddenly it's not so bad. If you group the results like this: 0-2, 3-5, 6-8, 9-11, 12-14, 15-17, 18+, your chances look something like this:
This is very similar to the system used in D6 Star Wars: if you need a result from 3-5 to succeed a Very Easy task, 6-10 for Easy, 11-15 for Medium, 16-20 for Difficult, etc. So with this Option you'd be looking at:
3-5 Easy (success roughly 82% of the time)
6-8 Medium (success roughly 27% of the time)
9-11 Difficult (success roughly 16% of the time)
12+ Very Difficult (success roughly 9% of the time)
None of these Options includes what happens when your dice mutate, as discussed in the previous post; it's just easier to reach higher results when they do.
I think Option #4 is my preference; what do you think?