Applying Modifiers

[redcrow]

Recently while writing up some situational modifiers for combat and difficulty levels for skills I came up with a bit of a conundrum.  Is it better for a modifier to be applied to the skill or to the dice roll?

Here is an example of what I'm talking about.  

A character has a skill of 65 with a longsword and receives a +10 modifier for attacking an opponents flank for a total score of 75.  The player rolls the dice and gets a 68, so the character scores a hit.

or

A character has a skill of 65 with a longsword and receives a -10 modifier to for attacking an opponents flank.  The player rolls the dice and gets a result of 73.  We subtract 10 for the modifier for a final result of 63, so the character scores a hit.

I want all modifiers and difficulties to remain consistent throughout the game (i.e. I don't want to mix the two).

Although each method appears to have pros and cons, I'm worried there is something I'm over looking.  Any thoughts?

[Bruce Baugh]

As a matter of cognitive psychology, addition is marginally faster for a lot of folks and feels more faster (if I may use the technical term :) ) than it is. While I don't know of any comparable hard info about the effects of applying modifiers at which step, I strongly suspect that applying modifiers before the roll, so that you end up with total X and roll to see if you get that or not without doing anything further to the roll measuring success or failure, will feel better to players. I personally sometimes feel had with a mechanic where I achieved what would normally be success  but which turns into failure after post-roll modifiers get applied, for what it's worth.

[szilard]

Which is better depends upon a lot of things, including the system you are using.

With the one you mentioned in your example, I'd go for modification of the skill - for the reasons Bruce mentioned (though I'd point out that it isn't always addition). In that case, though, they are mathematically equivalent, so that's not an issue.

If you are rolling a die pool vs. a target number, you can get mathy issues. Changing the target number has a different effect than changing the die pool.

Stuart

[Mike Holmes]

Keep in mind that perhaps the most attractive change that was made in ADD3E was to change all the modifiers so that + means good, and - means bad. If your system can stand it, always go that way. Again, as Bruce puts it, it seems that for a majority of players that this seems to feel correct, and as such is easier to remember and deal with.

In fact, this was first corrected in D&D design by Rolemaster which also, coincidentally is a "percentile" sort of system. That game solves the problem by having a constant target number. So, you add the +10 to skill to get 75, and then add your roll to get over 100 (actually there are graded results depending on how high you roll, but you get the idea). So not only are high modifiers good and high skills good, but high rolls are good as well. All keeps with that intuitive feel.

Mike

[redcrow]

Thanx for the input guys.  I thought adding to the skill was a bit more intuitive as well.  Something came up that made the other method seem like a viable solution to a problem, but I think in the long run it would cause more problems than it would solve so I'll stick with modifiers affecting the skill rather than the dice roll.

Though it was mentioned that people are generally intuitively faster at addition than subtraction, what about simple multiplication?

The reason I ask is that the combat system includes a damage bonus that depends on the result of the dice roll.  Originally I had come up with a chart that could be used to compare a characters skill with what they rolled to determine the damage bonus, but I hated the chart as it is cumbersome and I wanted to eliminate looking things up on charts as much as possible.  So I came up with (what I feel is) a simple formula that is applied to the skill (after modifiers if any) to determine what the damage bonus is.

So, the dice roll determines not only "if" you hit, but also "how well" you hit.  The damage bonuses are simply multipliers applied to whatever damage is rolled and they range from a 1x multiplier for an average hit, to as much as a 3x multiplier for a solid, well placed hit.  A low result on the to hit roll is better and scores more damage.  The ranges for damage multipliers increases as a character's skill increases.  So a highly skilled swordsman is more likely to hit where it hurts and hit more often than a less skilled person.

The formula works like this...

Skill (or less) = 1x damage multiplier (normal damage)
Skill x 0.4 (or less) = 2x damage multiplier
Skill x 0.1 (or less) = 3x damage multiplier
Always round down.

The 2x damage multiplier range may be difficult for some people to do, so as an alternate formula there is "Skill x 0.1 x 4 (or less) = 2x damage multiplier".

Now maybe you can see why I was considering making modifiers affect the dice roll rather than the skill.  By doing so I eliminate the need to apply the formula each time a modifier increases or decreases a skill.

What do you think? Is the formula simple enough, or would it bog things down because its too much math?

[xiombarg]

As I understand it, most people can deal with multiplication, but it's slower than addition. Way faster than division, tho -- and note that when I say "division" I include multiplying with a decimal. In my experience, dealing with fractions other than 1/2 tend to be considered "more complicated" by most people...

[Mike Holmes]

It would seem that your logic is that damage increases proportional to skill? Well, by that logic, wouldn't a bonus to skill make damage increase proportionally as well? To do other than add these together would mean a linear addition to damage.

Ex: If my skill is 50, then I normally have a 20 for x2, and a 5 for x3. If I subtract ten from the roll (as opposed to adding to skill), this essentially changes to 60. 30, 15. As opposed to adding to skill, and recalculating which results in 60, 24, 6. This disparity gets more extreme as the bonus increases. At, say, +30, you are at 80, 50, 35  vs. 80, 32, 8.

BTW, this is the system used in Call of Cthulhu where either five or ten percent of skill rolled under (can't recall exctly) produces an "impale" result for double damage.

The other option is to do the linear thing completely. Thus, you'd do like RM, add the roll, and then caculate damage from the result. Thus, 100 could be a hit for normal damage, a 140 for double, a 180 for triple. This, of course causes problems with limted ranges unless you use an open-ended system.

Another linear option is the Unknowm Armies method where a hit is anything less than your skill, but the higher the roll, the better. Thus, you could have a *3 damage within 5 of stat, a *2 within 20 of stat, and anything lower is x1 (in UA the damage is equal to the actual roll).

I take it that you need a "percentile" sort of system?

Mike

[redcrow]

It would seem that your logic is that damage increases proportional to skill?

Yes and no.  The potential damage range is independant of skill and always remains static.  Skill just determines whether you will hit in the upper portion of that range more often or less often.

A character with a skill of 15 can do the same maximum damage as a character with a skill of 85.  Its just that the character with a 15 skill won't do it as often.  Both character's know where to strike to do the most damage, but the lower skilled character isn't as quick or as good at slipping past his opponents guard or defenses.

Well, by that logic, wouldn't a bonus to skill make damage increase proportionally as well? To do other than add these together would mean a linear addition to damage.

Ex: If my skill is 50, then I normally have a 20 for x2, and a 5 for x3. If I subtract ten from the roll (as opposed to adding to skill), this essentially changes to 60. 30, 15. As opposed to adding to skill, and recalculating which results in 60, 24, 6. This disparity gets more extreme as the bonus increases. At, say, +30, you are at 80, 50, 35  vs. 80, 32, 8.

I think I understand where you are coming from.  However, the damage multipliers are based on the skill not on the dice roll.  So, with the modifiers applying to the dice roll, the damage multiplier ranges wouldn't change.  This creates a problem because then modifiers could (and most often would) make it impossible rather than simply more difficult to score damage multipliers.  Further down is how I had planned to solve this problem, but that solution has problems of its own as I note there.

BTW, this is the system used in Call of Cthulhu where either five or ten percent of skill rolled under (can't recall exctly) produces an "impale" result for double damage.

The impetus for my game design comes from the fact that I have played dozens of RPG's over the years.  Each one had an element or two that I really liked and thought worked well, but each also had many aspects that I thought could be done better.  I'm simply trying to combine all the things that I thought were good and worked well into a single system.  

As it stands so far, the combat system draws elements from at least 4 other RPGs that I can think of and the magic system draws from maybe 6 to 8 different sources.

So, there isn't much that is unique to my system other than it combines what I feel are the best mechanics from numerous other games.

The other option is to do the linear thing completely. Thus, you'd do like RM, add the roll, and then caculate damage from the result. Thus, 100 could be a hit for normal damage, a 140 for double, a 180 for triple. This, of course causes problems with limted ranges unless you use an open-ended system.

Rolemaster's open ended system definitely has its merits, but there are a few things about the implementation I never cared for.  There are a few elements I borrowed from RM, though.

Another linear option is the Unknowm Armies method where a hit is anything less than your skill, but the higher the roll, the better. Thus, you could have a *3 damage within 5 of stat, a *2 within 20 of stat, and anything lower is x1 (in UA the damage is equal to the actual roll).

That is an option too, and one that I considered to solve the problems with modifying the dice roll that I mentioned earlier.  The problem I have with it is that your potential for scoring in the upper range of damage doesn't ever increase with skill.  All that increases with this method is your ability to hit, but not your ability to hit where it hurts.

I take it that you need a "percentile" sort of system?

Mike

Yes, I'm designing things with a percentile mechanic in mind.  Right now the game requires D10's for % rolls to determine success for skills and combat and D6's to determine damage dealt in combat.  I tried to eliminate the D6's and just use D10's for damage, but had problems balancing hitpoints, armor's damage reduction, and weapon damage without an excess of math.  So I stuck with the D6's for damage simply because it makes combat run more smoothly.  I prefer a smaller range of dice used in the game and though 1 die type would be the best, 2 is acceptable.

[redcrow]

As I understand it, most people can deal with multiplication, but it's slower than addition. Way faster than division, tho -- and note that when I say "division" I include multiplying with a decimal. In my experience, dealing with fractions other than 1/2 tend to be considered "more complicated" by most people...

Well, I could perhaps explain it another way.  Such as drop the second digit to find the 3x multiplier.  Drop the second digit and multiply by 4 to find the 2x multiplier.  Its basically the same thing, but do you think that would be easier for people to work with than the multiplication with decimals?

[Mike Holmes]

It would seem that your logic is that damage increases proportional to skill?

Yes and no.  The potential damage range is independant of skill and always remains static.  Skill just determines whether you will hit in the upper portion of that range more often or less often.

Right, so proportional over time. That is, higher skill means more damage more often. You're just disagreeing with my terms, not the logic.

I think I understand where you are coming from.  However, the damage multipliers are based on the skill not on the dice roll.

Six of one, half dozen of the other. Adding ten to the skill is the same as subtracting ten from the die roll, mechanically. The only difference is whether we're calculating the breakpoints pre-or post modifier.

My point is that, while more cumbersome, doing the math to determine the breakpoints after adding modifiers to skill means that you'll never have the problem of max damage being impossible (not considering rounding or total limits on the range vs modifiers). Thus, with the pre-calc concept, if I have a 50 skill, and get a 10 point penalty modifier, I have to add it to my roll, resulting in a minimum roll of 10, which is 5 above what I need for max damage. With the post-calc method, I subtract the 10 from my 50 leaving 40, which means I still have a 4% chance of max damage. The only point at which I would not have a chance at max damage is when my skill dropped to less than 5 or 10 percent (depending on rounding), which might be appropriate anyhow.

What does happen if I have a 25 skill, and 30 points in penalties? Automatic failiure?

The impetus for my game design comes from the fact that I have played dozens of RPG's over the years.  Each one had an element or two that I really liked and thought worked well, but each also had many aspects that I thought could be done better.  I'm simply trying to combine all the things that I thought were good and worked well into a single system.

My poorly made point was you might want to look at CoC to see how they do it, as it might be informative.

Mike

[redcrow]

What does happen if I have a 25 skill, and 30 points in penalties? Automatic failiure?

Regardless of bonuses or penalties a natural die result of 01 is always a hit and result of 00 is always a miss.  So if a penalty reduces your skill to -50, you could still hit by rolling a 01, or conversely if a bonus increased your skill to 150, you could still miss by rolling a 00.  In the case of the former, the GM is of course capable of determining that something is simply impossible.  In this situation the GM simply needs to inform the player that the attempt is doomed to failure.

Applying the modifiers to the skill rather than the dice roll does seem intuitively better, but what are your thoughts on the formula for determining damage multipliers.  Is it simple enough that most people could do it without the need of a calculator?

My poorly made point was you might want to look at CoC to see how they do it, as it might be informative.

My poorly made point was that CoC as well as many other games have been very informative already. ;-)

[Mike Holmes]

Regardless of bonuses or penalties a natural die result of 01 is always a hit and result of 00 is always a miss.  So if a penalty reduces your skill to -50, you could still hit by rolling a 01, or conversely if a bonus increased your skill to 150, you could still miss by rolling a 00.  In the case of the former, the GM is of course capable of determining that something is simply impossible.  In this situation the GM simply needs to inform the player that the attempt is doomed to failure.

For the 01 auto success, I assume x1 damage? I assume that modifiers would never raise effective skill over 250? Because at that point all rolls would do double damage, except for the failure condition on 00.

Applying the modifiers to the skill rather than the dice roll does seem intuitively better, but what are your thoughts on the formula for determining damage multipliers.  Is it simple enough that most people could do it without the need of a calculator?

Unfortunately, no. Actually, that's not true, most people can do it, but they won't want to. That level of math is considered "too much" by the vast majority, IME.

Heck, they won't even like doing it before play, even with a calculator.

I'm not sure how to get around this without major revamps.

Mike

[redcrow]

For the 01 auto success, I assume x1 damage? I assume that modifiers would never raise effective skill over 250? Because at that point all rolls would do double damage, except for the failure condition on 00.

Yes, in that instance it would only be a x1 damage. No, modifiers would never raise effective skill over 250 and honestly I can't think of any combination of modifiers that would bring a skill anywhere close to that.  Even a modified skill as high as 150 would be extremely rare.

[/quote]Unfortunately, no. Actually, that's not true, most people can do it, but they won't want to. That level of math is considered "too much" by the vast majority, IME.

Heck, they won't even like doing it before play, even with a calculator.

I'm not sure how to get around this without major revamps.

Mike[/quote]

I'm not sure how to get around it either.  I have thought of many ways of doing things, but this was the first method that really "felt right" to me.

I would be interested if you could recommend an RPG that does a good job at simulating a sort of Three Musketeers/Swashbuckler themed combat system.  Something that implements feints, parries, ripostes, etc., well?

My setting is sort of a Three Musketeers meet Cthulhu theme, so the swashbuckling style combat is what I'm looking for.

[Mike Holmes]

I would be interested if you could recommend an RPG that does a good job at simulating a sort of Three Musketeers/Swashbuckler themed combat system.  Something that implements feints, parries, ripostes, etc., well?

My setting is sort of a Three Musketeers meet Cthulhu theme, so the swashbuckling style combat is what I'm looking for.

Oh, why didn't you ask that in the first place? See Flashing Blades, The Riddle of Steel, and 7th Sea. TROS can be found on the independent game forums page. Does everything you want, and probably more than you imagined.

Mike

[Jason Kottler]

Check out The Riddle of Steel for a combat system that does a great job with cut, thrust, parry, riposte, feint, and more.

And you know, I haven't heard many things about it here, but GURPS combat always at least made sense to me, unlike the combat in many other games (Storyteller, Shadowrun, D&D, etcetera, etcetera, etcetera).

Completely off topic: If the definition of indie around here is "Creator Owned", does GURPS qualify as an indie RPG?