Like it says, I've been trying to come up with an RPG mechanic that revolves around the notion of skills being arranged in a hierarchy, going from vague, flexible and relatively weak abilities that progress down to more refined, specialised, and powerful skills.  A category of related skills would thus form a tree structure, with 'parent' and 'child' skills diversifying to model a character's portfolio of strengths (and perhaps weaknesses.)

To give an example- which will probable be needed to explain the problems I've been having, a straightforward warrior might have the following development of skills. (parent skill is listed in brackets after the child skill name.)
[code]

Life[]  2
  Body[Life]  4
    Brawn[Body]  7
    Vigour[Body]  5
    Foritude(injury)  6
  Mind[Life]  3
    Artifice[Mind]  6
      Combat[Artifice]  10
        Melee[Combat]  14
          Parry[Melee]  16
            Fencing[Parry]  19
        Proficiency(sword and dagger)[Combat]  13
          Proficiency(rapier)[Proficiency(sword and dagger)]  17
    Knowledge(general)[Mind]  5
      Knowledge(humans)[Knowledge(general)]  9

[/code]

You can see what I'm getting at here.  Child skills are more powerful than their parents (which can substitute for them in a pinch,) but come at the price of specialisation.  This allows you to effectively abolish the distinction between attributes, skills, attack bonus, etc. etc. and permit the player to specialise solely in whatever set of qualities are best suited for the setting and style of play.

So far, so good.  Where I've been having significant problems is in the area of support skills- skills which aren't direct ancestors or children of eachother, but nonetheless benefit eachother in application.
For example, the above warrior should be able to use his proficiency with the rapier and knowledge of humans to increase his effectiveness in combat- when fencing against human opponents with a rapier.  (This problem is further complicated by the fact that he (obviously) won't get this bonus if he's hunting lions with a blunderbuss, but that's another issue.)  How would you model this kind of synergy?  Let them make several checks and keep the best result?  Add 1/2 skill level?  How do you exclude the effects of common ancestor skills?  Am I just going about it the wrong way?

Is it just me but I can't see your example just and empty grey square!
Best
JW

Um, just do it. Have a rule saying that if a character possesses a skill that would be relevant to the situation but is less central than the skill their rolling with, add a bonus based on the rating of the related skill. If this is too cost beneficial (its easier/cheaper to wrack up secondary bonuses than improve the main skill) you might want to make the player pay for these synergizes some how. Like for X points (of whatever) you can add 1/5th of your Knowledge (Humans) to your Proficiency (Sharp Pointy Things) rolls when attacking humans...

Also, I imagine melee here means what it does in D&D, but just so you know, it doesn't mean that outside of that particular game, so maybe there's a better term. Also, "proficiency" smacks of D&D-ness. Of course, that's just my tastes, so feel free to ignore this last paragraph.

Is it just me but I can't see your example just and empty grey square!
Best
JW

Um, just do it. Have a rule saying that if a character possesses a skill that would be relevant to the situation but is less central than the skill their rolling with, add a bonus based on the rating of the related skill. If this is too cost beneficial (its easier/cheaper to wrack up secondary bonuses than improve the main skill) you might want to make the player pay for these synergizes some how. Like for X points (of whatever) you can add 1/5th of your Knowledge (Humans) to your Proficiency (Sharp Pointy Things) rolls when attacking humans...

Also, I imagine melee here means what it does in D&D, but just so you know, it doesn't mean that outside of that particular game, so maybe there's a better term. Also, "proficiency" smacks of D&D-ness.

Least important comment first: Screw terminology. Explain what you mean, and worry about what to call it later on in the development process. Just go with what's easy.

Secondly, if you structure your skills a little bit differently, it might get rid of the problem. Try something like this:

Life[]  2
  Body[life]  +2
    Brawn[Body]  +3
    Vigour[Body]  +1
    Foritude(injury)  +2
  Mind[life]  +1
    Artifice[Mind]  +3
      Combat[Artifice]  +4
        Melee[Combat]  +4
          Parry[Melee]  +2
            Fencing[Parry]  +3
        Proficiency(sword and dagger)[Combat]  +3
          Proficiency(rapier)[Proficiency(sword and dagger)]  +4
    Knowledge(general)[Mind]  +2
      Knowledge(humans)[Knowledge(general)]  +4

So this way, you're fighting with proficiency rapier (Life(2) + Mind(1) +Artifice(3) +Combat(4) +Sword and Dagger(3) + Rapier(4) = 17) against a human (+4) for a total of 21. (fencing and proficiency rapier are kinda redundant, unless there's something I just don't get) If you did add fencing it would be 24.

Now maybe instead of adding the full 4 points of any synergy skills, you could halve them, so in the above case it would be a total of 19.5 (round up or down) with knowledge: humans and fencing thrown in.

Hello Alfryd,

Well, you have a lot of options, depending on how you want the setup to work.

a): You could, as has been mentioned, allow the two to come from the same ancestor areas, and roll both as full Skills. This will require you to have a sub-mechanic that spells out what level of success on the knowledge aspect means as a form of bonus on the melee aspect.

b): You could separate the trees so that they *dont* share ancestors. Following this option, if I were in your position I would base combat skills off of a physical Parent. You will still need to work out a sub-mechanic, as in "a," so players will know what kind of bonus they get.

c): You could make specific Knowledge a kind of Specialization/bonus that is bought separately. The real plus with this option is that it will reduce the amount of rolling required (no need for a sub-mechanic). You also don't have to worry about ancestor skills or parent skills. Also, your Knowledge (humans) bonus of +4 (or whatever) could then readily be applied to other Skill trees, without having to worry about worming it into the actual tree structure for each one. "First Aid check final total 15, with my +4 Human Knowledge bonus, is 19. What's my difficulty on this roll?"

Good Luck!

-a-

(fencing and proficiency rapier are kinda redundant, unless there's something I just don't get)

So this way, you're fighting with proficiency rapier (Life(2) + Mind(1) +Artifice(3) +Combat(4) +Sword and Dagger(3) + Rapier(4) = 17) against a human (+4) for a total of 21. ...If you did add fencing it would be 24.

Now maybe instead of adding the full 4 points of any synergy skills, you could halve them, so in the above case it would be a total of 19.5 (round up or down) with knowledge: humans and fencing thrown in.

c): You could make specific Knowledge a kind of Specialization/bonus that is bought separately. The real plus with this option is that it will reduce the amount of rolling required (no need for a sub-mechanic). You also don't have to worry about ancestor skills or parent skills. Also, your Knowledge (humans) bonus of +4 (or whatever) could then readily be applied to other Skill trees, without having to worry about worming it into the actual tree structure for each one. "First Aid check final total 15, with my +4 Human Knowledge bonus, is 19. What's my difficulty on this roll?"

Alfryd wrote:

Like it says, I've been trying to come up with an RPG mechanic that revolves around the notion of skills being arranged in a hierarchy, going from vague, flexible and relatively weak abilities that progress down to more refined, specialised, and powerful skills.  A category of related skills would thus form a tree structure, with 'parent' and 'child' skills diversifying to model a character's portfolio of strengths (and perhaps weaknesses.)

Unless I'm missing something, you just need a suitable resolution mechanic that can factor support ability bonuses fast and easy. Then you can just go case-by-case while playing, picking any abilities that suit the situation, pick the most important one as primary (if you want to have that distinction, that is) and check the others for bonuses to the primary. That's a simple, fast and flexible system that's also difficult to unbalance. The Shadow of Yesterday, incidentally, works like that.

Of course, picking the right resolution mechanic might be difficult, especially if you have some other requirements for it to fulfill as well. For example, if you're doing percentage roll-under, this is all very easy: just roll the support abilities and halve the chance of failure for each successful support. But it all depends on how your exact resolution mechanic works: how those ability scores are used to determine success and failure?

My example was admittedly somewhat simplistic. You wouldn't have to add up the score for Rapier every single time.. You'd have the current total for each subskill listed next to it's bonus.. So it'd be more like this:

Life[]  2
  [...]
  Mind[life]  +1 = 3
    Artifice[Mind]  +3 = 6
      Combat[Artifice]  +4 = 10
        Melee[Combat]  +4 = 14
          Parry[Melee]  +2 = 16
            Fencing[Parry]  +3 = 19
        Proficiency(sword and dagger)[Combat]  +3 = 13
          Proficiency(rapier)[Proficiency(sword and dagger)]  +4 = 17
    Knowledge(general)[Mind]  +2 = 5
      Knowledge(humans)[Knowledge(general)]  +4 = 9

Then you choose the primary (for my previous example I chose Proficiency Rapier) and add the individual sub-bonuses of each applicable support skill.

Also, to expand upon my comment about the redundancy of rapier and fencing.. If you're proficient with a rapier, you're not going to be proficient in using it in ways it's not meant to be used. You won't have learned how to hack with it like it were an axe, or bash with it as if it were a club. You will be proficient in using it as though it were a rapier, which is fencing. So, my personal, outsider's perspective on this is that you should have one or the other, but not both.

Now what does this mean if you have the proficiency rapier, but you use a broadsword? In that case, you'd just use your sword and dagger skill, assuming that this refers to skill with both swords and daggers (slicey-stabby implements) rather than a particular combat style utilizing both a sword and a dagger. If that assumption is wrong, then you'd just use combat.

You might try something fairly simple like counting the number of related skills that apply, with higher numbers of skills contributing a diminishing amount to the current roll. A single related skill adds so much, two skills add a little more, and so on, without considering how related the skill is. Very simple. Not sure if that's what you're looking for, but I thought I'd throw it in there.

would my synergy bonus model work if you included both the total and the amount that particular aspect was raised? For example Knowledge (Humans) could be listed as +9/+6. 9 is the skill level when used alone, and 6 would be the synergy bonus when used with another Mind Skill, or, if you want synergies to be less effectual, that second number could be halved. So it would be listed as +9/+3... this seems simple and intuitive, is there something I'm missing that wouldn't allow it to work?

Then you choose the primary (for my previous example I chose Proficiency Rapier) and add the individual sub-bonuses of each applicable support skill.

For example Knowledge (Humans) could be listed as +9/+6. 9 is the skill level when used alone, and 6 would be the synergy bonus when used with another Mind Skill, or, if you want synergies to be less effectual, that second number could be halved. So it would be listed as +9/+3... this seems simple and intuitive, is there something I'm missing that wouldn't allow it to work?

I think that the first order of business is to try and work out what you want this system to do. Are you looking for something that will naturally focus a character's development as they advance? Are you, perhaps, looking for something that is an understandable model of character progression? Are you looking for a system that is quick and easy to administer?

Of course, picking the right resolution mechanic might be difficult, especially if you have some other requirements for it to fulfill as well. For example, if you're doing percentage roll-under, this is all very easy: just roll the support abilities and halve the chance of failure for each successful support. But it all depends on how your exact resolution mechanic works: how those ability scores are used to determine success and failure?

Alfryd wrote:

My main concern was, for wont of a better word, realism.  I wanted to use skill hierarchies and support skills because it's a natural mimcry of how skills actually develop and interact.  So, I want to keep that if remotely possible.

Wolfen has suggested that seperate skills for fencing and rapier proficiency may be redundant, but that can probably be fixed.

What I wanted to redress was the problem that, in many RPGs, two closely related skills/attributes are essentially treated as largely independant.  For a simple example, consider Strength and Constitution in D&D.  In realistic terms, it is extremely unlikely that a person could develop high strength (muscle mass through exercise) without substantially improving their constitution in the process (organ capacity, aerobic fitness.)  In GURPS, there's an informal solution using... what are they called, talents?- well, specific skills that boost all checks from a closely related group- 'smooth operator' for social skills, machine expertise, etc.
But then it occured to me that the simpler thing to do would be to abolish the distinction between skills and attributes entirely.  Any skill could have any other skill as a 'key attribute'.  (Maybe even several, if it's performance was dependant on/benefitted from multiple factors.)

Alfryd,

As someone who likes "realism" in his RPGs as well, I'd like to weigh in on the topic you just brought up.

To address your D&D example specifically, it's actually not at all unrealistic. Looking at what Constitution affects in D&D, it is quite possible, and even likely, for person with a high strength to have a low constitution. In our modern day world, it's even common. Consider the strong fat guy, or the body-builder that neglects aerobic fitness, and concentrates on foods that will bulk him up, rather than make a balanced healthy diet. Both of these guys can be exceptionally strong, but will never be able to run a marathon, and may be susceptible to illness. Now, "hitpoints", which reflect the ability to take a beating and keep going may be tied to body bulk, which can be related to strength, but this isn't necessarily true, even in D&D. hitpoints may as easily be reflected as the ability to roll with a punch, which would be more likely to tie into dexterity.

Now, this isn't to say your answer isn't a good one, so long as it serves the goals you're going for in your game. I just wanted to briefly address this topic.

To address this line, now:

Any skill could have any other skill as a 'key attribute'.  (Maybe even several, if it's performance was dependant on/benefitted from multiple factors.)

Thank you for the feedback.

. Now, "hitpoints", which reflect the ability to take a beating and keep going may be tied to body bulk...

Looking at what Constitution affects in D&D, it is quite possible, and even likely, for person with a high strength to have a low constitution.

What do you mean by this? Are you saying that you can, in your system, choose to have fencing be descended from knowledge: general? After all, it could be argued that you learned to fence by studying the written works of the sword masters, which led from your more generalized thirst for knowledge?

Hi Alfryd,

I too like skill-tree realism.  Here's an idea for a point-buy system.  If that's not an option for you, this won't be usable, but... maybe food for thought?

Basically, the idea is that buying and advancing a broad ("parent") skill is expensive, and buying a specific ("child") skill is cheaper.

System 1:
Let's say you have 12 points to spend.

Sleight of Hand costs 4 points per rank.
So, you can spend your points to get rank 3.
You can use Sleight of Hand to do various things (including pick a lock) wth a +3 on your roll.

Pick Locks normally costs 2 points per rank.
You can take Pick Locks without taking Sleight of Hand.
So, you can spend your 12 points to get rank 6.  That's a +6 on your rolls to pick locks only.

However, if you take Sleight of Hand (parent) and Pick Locks (child), the costs you pay for Pick Locks are now only to advance it beyond your rank in Sleight of Hand.  So if you pay 8 points for 2 ranks of Sleight of Hand, you can still pay 4 points for 2 more ranks of Pick Locks.  Thus you wind up with a +2 to any Sleight of Hand roll and a +4 to specifically picking locks.

System 2:
Sleight of Hand cannot be used to pick locks, but having Sleight of Hand reduces the cost of Pick Locks for that character from 2/rank to 1/rank.  So those 4 leftover points (after spending 8 on Sleight of Hand) can be used to buy 4 ranks in Pick Locks (instead of the 2 ranks they'd buy without Sleight of Hand).

System 3:
Combine 1 & 2.  8 points buy 2 ranks in SoH, 4 points buy 4 more ranks in PL, producing a total of 6 ranks in PL.

System 4:
Any of the above, but with an addition:
Spending points in PL gives you half that many points' worth of SoH.  E.g., spend 8 points in PL, get 4 points' worth of SoH (1 rank).  This means that your lock-picking expert necessarily has some ability at other Sleight of Hand tasks, which seems realistic to me.

Hope this wasn't off-topic...
-David

Alfryd wrote:
Wolfen has suggested that seperate skills for fencing and rapier proficiency may be redundant, but that can probably be fixed.

wrote:
What I wanted to redress was the problem that, in many RPGs, two closely related skills/attributes are essentially treated as largely independant. 

Hope this wasn't off-topic...

It seems to me that this can only be done if you create a definite body of skills, each of which has the same impact on the game as any other.

It seems to me that the value of a statistic in a game is mostly so that the player can get a handle on what their character is like, rather than to be capable of generating a bonus accurately . Perhaps it's unlikely that a character would be strong and unhealthy. But, it is easier to grasp, and that makes it easier to play.

I suspect a game that is real-world accurate is not as attractive as a game that lets a player draw their character with ease.

Alfryd wrote:

It seems to me that this can only be done if you create a definite body of skills, each of which has the same impact on the game as any other.

I'm not sure I understand exactly what you mean.  Presumably every skill, by virtue of having different effects, will have a different impact?  Are you talking about balancing their relative values, or do you just want to see more specific examples?

wrote:

It seems to me that the value of a statistic in a game is mostly so that the player can get a handle on what their character is like, rather than to be capable of generating a bonus accurately . Perhaps it's unlikely that a character would be strong and unhealthy. But, it is easier to grasp, and that makes it easier to play.

What struck me, for instance, as a major deficiency of D&D is that attributes are difficult to develop significantly after character creation (you get a 1-point bonus every 4 levels, IIRC.)  But things like strength, fitness, flexibility and even intelligence or charisma can all be trained extensively and improved through practice.

wrote:

I suspect a game that is real-world accurate is not as attractive as a game that lets a player draw their character with ease.

I'm not sure I really understand your criticism here.  Is there something inherently difficult to understand about general vs. specific skill sets?

@Velcanthus

Balancing their relative values.
How would this system provide a cure for that particular deficiency?

However, it seems to me that a skill-based system is just at odds with reality as D&D. After all, you can't expect to increase your chance to hit an opponent with a sword once you have worked out how it works.

Beyond weapon familiarity, what determines whether or not you scored a hit is based on your ability to predict where your opponent will be. And, your willingness to hit them. Surely, that is not a function of any particular weapon skill. I've been in a few bar fights. The guy who could juggle snooker balls never worried me. The guy who was quite happy to throw them at people gave me grave concerns.

However, if you take Sleight of Hand (parent) and Pick Locks (child), the costs you pay for Pick Locks are now only to advance it beyond your rank in Sleight of Hand.  So if you pay 8 points for 2 ranks of Sleight of Hand, you can still pay 4 points for 2 more ranks of Pick Locks.  Thus you wind up with a +2 to any Sleight of Hand roll and a +4 to specifically picking locks.

Sleight of Hand cannot be used to pick locks, but having Sleight of Hand reduces the cost of Pick Locks for that character from 2/rank to 1/rank.  So those 4 leftover points (after spending 8 on Sleight of Hand) can be used to buy 4 ranks in Pick Locks (instead of the 2 ranks they'd buy without Sleight of Hand)...
Combine 1 & 2.  8 points buy 2 ranks in SoH, 4 points buy 4 more ranks in PL, producing a total of 6 ranks in PL.

Spending points in PL gives you half that many points' worth of SoH.  E.g., spend 8 points in PL, get 4 points' worth of SoH (1 rank).  This means that your lock-picking expert necessarily has some ability at other Sleight of Hand tasks, which seems realistic to me.

Alfryd wrote:

@Velcanthus

However, it seems to me that a skill-based system is just at odds with reality as D&D. After all, you can't expect to increase your chance to hit an opponent with a sword once you have worked out how it works.

I honestly can't see where you're coming from here.  Are you saying that a skilled swordsman would fare no better in combat than someone who'd never picked up a blade before?

Beyond weapon familiarity, what determines whether or not you scored a hit is based on your ability to predict where your opponent will be. And, your willingness to hit them. Surely, that is not a function of any particular weapon skill. I've been in a few bar fights. The guy who could juggle snooker balls never worried me. The guy who was quite happy to throw them at people gave me grave concerns.

Alfryd wrote:
I think this relates more to morale effects and knowing who's likely to start a fight, than to skill in combat per se.  But, just for the moment, if we assume that this is true, then you'd just have a general Combat skill, with particular styles of fighting (perhaps with particular weapons) as child skills.  Are are you saying that weapon proficiencies should be modelled as one-shot feats, or that their contribution is relatively small (entailing high XP cost to slow levelling?)

I think that modeling this realistically means that weapon familiarity gives you a reasonably large starting bonus, which quickly plateaus. It would behave like a logarithmic function.

But, then, I would only be doing this because I was interested in realism. It seems to me that the most important job that a game can do is provide a means of describing things to everyone involved in a clear and concise manner.

People who can model human interactions with the world accurately would not be designing rpgs. They'd be working for NASA.

Alfryd wrote:
What about parent proficiencies for broad categories of weapons?  Would you say these stack with the child bonus before diminishing returns, or apply seperately?