I had a somewhat new idea for a game mechanic. Tell me what you guys think.

CORE MECHANIC SYSTEM

+ Roll Luck Dice (4d6)
+ Add Ability Modifier and Skill Modifier (These two numbers added together constitute your Chance for Success, or CS)
+ Subtract CS from Luck Roll
+ Compare CS - Luck Roll against FATE (FATE is more or less the Target Number set by either the GM, or guiding rule) If CS - Luck Roll is equal to or less than FATE, then the roll succeeds, however if CS - Luck Roll is higher than FATE, then the roll fails.

FATE DIFFICULTY RANGE

24    Very Easy
18    Easy
12    Average
6    Tough
0    Challenging
-6    Formidable
-12  Mind Numbing
-18  Heroic
-24 Almost Impossible

Anyway, there you go guys, please respond with what you think. Also, can someone point me to a resource for dice statistics, specifically one that would give say, the odds of getting number X with 4d6.

Kyle,
It's hard to think something of a mechanic in isolation. I'm sure you have some application in mind, could you tell us something about that?

Having said that, I'll make a comment anyway :-) I would recommend reconsidering some of the terms you are using. For example, if I understand you right, a high Chance of Success actually means that you are likely to fail. Similarly, this means that I want my Ability and Skill to be low, not high. Nothing wrong with that, but you may want to reflect it in the names.

Or, maybe I just misunderstood your explanation. If that is so, could you please work an example?
SR
--

the way i understand it is "Large CS = Good" cos its neutralising the large (4D6!) luck roll and bringing the result under the TN.

To critique: subtraction and negative numbers are harder to deal with than addition. I would only use them if 0 had special significance and in your system it doesnt appear to.

Why not have 4D6+CS vs FATE (equal or higher to succeed)? Its identical (i think) just easier to work out.

Kyle wrote:
Anyway, there you go guys, please respond with what you think. Also, can someone point me to a resource for dice statistics, specifically one that would give say, the odds of getting number X with 4d6

One thought: subtraction is much harder for people to do than addition. Your system would have the same probabilities if you rolled 4d6+CS against the difficulty (0 for easy, 24 for challenging, 48 for almost impossible).

I'm assuming Rob's confusion is due to the following being an error:

Compare CS - Luck Roll against FATE

Compare Luck Roll - CS against FATE

Kyle

Just as a rule of thumb, game mechanics that require players to do adding and subtracting are slower and more prone to break down.

Recently I offered up "The Machine Model of Games" http://www.indie-rpgs.com/forum/index.php?topic=17125.0 That talks about games having 1. Static (irrelevant information that obscures the important stuff), 2. Overload (requiring players to remember more than our brains easily do), 3. Friction (mechnics that require a lot of work and grind out results slowly) and 4. Waste (Mainly time used up not getting on with the purpose of the game (a subjective experience).

Mechanism that require adding are hard, subtracting is harder, multiplying is a little harder than that, and division is down right hard (at least to do in one's head - quickly). All have a lot of friction in them.

If there is too much friction players tend to skip the rule (frequently due to overload) and can feel it wastes their game time.

As a general rule I try to avoid all computations above adding.

As to the mechanic itself - I think it looks fine. It takes player's skill and luck into account while giving game masters power to adjust difficulty levels based on what is happening in the game.

Examples of past adding subtracting resolution games.

I played in a 1890's British Colonial game where the Dervish Sudanese faced British machineguns. We added up fire power, modified it by range, morale, training, etc. and then rolled a die. I noted that the outcome was between one and six casualties. It hit me that we could have gotten the same result rolling a single d6 (without the fifteen minutes of adding and subtracting.) I later ran a WWI game using the 1d6 method and it worked. In fact it captured the feeling of hopelessness that WWI gave to people.

Around 1970 miniatures games used adding subtracting methods that were then applied to a chart to see exactly how many men were killed (where each figure represented 20 men). UGH! Games dragged. They had accounting an computation.

Chris Engle
Hamster Press = Engle Matrix Games

Ignore my earlier chart.  My memory of JAGs is pretty foggy and that bell curve isn't steep enough so they must a mechanic to flatten it out a bit.  Normally the chance of getting a 4 or a 24 on a 4D6  is or about 0.00771604938.  And my hunch is that most of the values will be in the 12-16 range. 

If that is the case, why not use a D6?  If you want to give the players the ability to ocassionally score high, how about an exploding D6 (to avoid discontinuities treat the 6 as a zero and have five allow an additional reroll ad infinitum). 

If you like having a large range of values you could use a D20 .  If you like some curvature and don't want opposed rolls make it 3 D20s and select the middle valued die as your result.  If you were planning to use opposed rolls anyway for some types of conflict and want curvature just have each side roll a D20 and added it to a value.

At this point this thread is just a pinata, everybody here is poking away blindly. 

Did you have any particular concerns?

Kyle, there's nothing wrong with your mechanic, but the way you've presented it suggests there are certain assumptions you're making which you might want to re-examine, such as
- "characters have abilities and skills": not always. Some games let you choose any terms you want to describe your character (e.g. HeroQuest, Universalis), others use terms that have nothing to do with any kind of ability vs. skill breakdown (e.g. My Life With Master, where a character is defined by scores in Self-Loathing, Weariness, and Love; a list of Connections, i.e. NPCs in which Love is invested; a "Less than Human" weakness and a "More than Human" power, neither of which is rated numerically).
- "there's a GM": again, lots of games have no GM, or, more accurately, break up the GM's powers among the players either evenly (Capes, Universalis again) or in a specific division of labor (Polaris)
- "we resolve things by rolling dice": besides games involving cards (Nine Worlds), there are others with no random element at all (Amber Diceless Rolepaying)

You might also do well to look at this discussion on Vincent Baker's blog about the difference between "task resolution" and "conflict resolution" : Your system could be used for either as you've presented it, but they're very different, and the difference is worth considering.

Wow, I am overwhelmed by the amout of responses Guys! Thank You.

However, I chose the 4d6 to try and get away from D20. It is my opinion that if you are going to create a d20 System  the Ability + Skill + Roll = Target Number device suits it the best, thus the Wizard's OGL. However, I didn't want to go this route for two specific reasons, first of all I don't want to devote an entire page in my book to copyright with Wizard's of the Coast, Inc. plastered all over it. Secondly, I wanted to create something, if not unique, different enough to call my own. I know you can't copyright a game mechanic, but this is all for fun anyway.

Anyway, with that said I will move on to try and expalin this mechanic a little bit better. I wish this could be in a live conference with audio, so I wouldn't have to type everything. But anyway. Here goes.

The 4d6 exists as your character's luck which is supposed to be nuetral, not sure if I achieved that however.
The Ability Modifier and Skill Modifer are added together to form the Chance for Success Number, which is then subtracted from the Luck Roll
Next, the totaled number is compared against the FATE Number (Difficulty)

So In essence what we have is a roll under system. -----------> Ability + Skill - Roll =< Target Number

+ Roll Luck Dice (4d6) The LOWER you roll here the better
+ Add Ability Modifer and Skill Modifier together  This becomes the Chance for Success You want these number to be as high as possible to get the CS - Luck Roll as low as possible.
+ Subtract CS from Luck Roll
+ Compare CS - Luck Roll against FATE (Difficulty) Because we're trying to roll under, the lower the number you can achieve becomes benneficial to compare against the FATE Number

Maybe this will help some of the confused posters. I was more concerened about whether or not the dice probabilities would come out to a middle of the road difficulty. Maybe being a little bit easier for lower characters, and getting a little harder as the character progresses. I'm not a mathmatician, so numbers and I don't jive.

However, I can see where this is a bit more difficult to play with than the straigh up D20. However, I do want to mention, that I don't like FUDGE and GURPS, so please don't menton them as options. Thanks

Kyle wrote:

+ Add Ability Modifer and Skill Modifier together  This becomes the Chance for Success You want these number to be as high as possible to get the CS - Luck Roll as low as possible.

I mest up when I was writing this, it should read like this:

+ Add Ability Modifer and Skill Modifier together  This becomes the Chance for Success You want these number to be as high as possible to get the CS - Luck Roll as HIGH as possible.

Kyle wrote:
I do want to mention, that I don't like FUDGE and GURPS, so please don't menton them as options. Thanks

I'm glad to hear that about GURPS and FUDGE, a while I was posting about a different version of this mechanic, and someone, I forget who, was singing their praises, and repeatedly.

Anyway, as I stated above I just wanted to make sure that the actual math of that system works, and I don't want to create something that is a hasssle to understand and play. (KISS) Keep It Simple Stupid!  LMAO!

Kyle wrote:
I'm glad to hear that about GURPS and FUDGE, a while I was posting about a different version of this mechanic, and someone, I forget who, was singing their praises, and repeatedly.

Also, you might want to check out some good, free games that might suggest alternatives to the D20/GURPS/FUDGE/Storyteller model:

Torchbearer
Legends of Alyria
and Capes "light" (actually the preview/demo version of a game you have to buy)

Kyle wrote:
I had a somewhat new idea for a game mechanic. Tell me what you guys think.

CORE MECHANIC SYSTEM

+ Roll Luck Dice (4d6)
+ Add Ability Modifier and Skill Modifier (These two numbers added together constitute your Chance for Success, or CS)
+ Subtract CS from Luck Roll
+ Compare CS - Luck Roll against FATE (FATE is more or less the Target Number set by either the GM, or guiding rule) If CS - Luck Roll is equal to or less than FATE, then the roll succeeds, however if CS - Luck Roll is higher than FATE, then the roll fails.

FATE DIFFICULTY RANGE

24    Very Easy
18    Easy
12    Average
6     Tough
0     Challenging
-6    Formidable
-12  Mind Numbing
-18  Heroic
-24 Almost Impossible

Kyle wrote: + Subtract CS from Luck Roll
+ Compare CS - Luck Roll

A lot of how this plays depends on the values you're allowing for Ability and Skill, but the curve is already rough.

4d6 provides 6x6x6x6=1296 permutations, of which exactly 1 will be all ones and the same all sixes. So your extremes appear a bit less than one time in a thousand. The next step, 5 or 23, each appear 4 times in 1296, or once in 324 (I'm doing these numbers in my head, but if they're wrong, they're close), which added to the extreme means 5 chances to roll not greater than 5 (which of course is the more desireable roll), 1/259, roughly. Permutations get very complicated after that, but generally the more dice you have in play the more tightly your results will tend toward the center point--in this case, rolls of 14 will be extremely common.

The question then is whether you want a randomizer that is so focused on the center.

If you're looking for ways to generate curves with 24 at the high end, 3d8 is considerably gentler (512 permutations), and 2d12 is pretty much straight up and straight back down again, starting with 1/144 at the extremes (2 and 24) and climbing to a peak of 13/144 at the centerpoint (13).

I know there are people here with software to calculate the permutations quickly; I don't have that right now, but I really do have trouble with a 4d6 curve if you're not trying really hard to minimize the impact of the randomizer.

--M. J. Young