It's difficult to do in such a way that it doesn't end being slower than just rolling in damage.

Margins of success works well in dicepool games but I find it slower in single dice games then just rolling the damage.

If fixed damge doesn't work you could just use an odd even flip.  This allows you to distinguish damage based on swingness of weapons as well.

Eg: you determine damage based on whether the attack roll is odd or even.

Greatsword = odd 5, even 8
Great Axe = Odd 3, Even 10.

I like the idea of using margin of success for damage quite a lot; in fact that's the approach I'm using for my current design project.  I like having margin of success matter, and I like speeding things up by removing a step from the process.

I've heard mentioned here and elsewhere that rolling another die is faster.  That hasn't been my experience.  In my game at least, totals rarely go over 20.  I can subtract numbers in this range in my head faster than I can speak the result, and so can most of the folks I play with, even the kids.

As for the point about giant weapons etc, that doesn't really fit with my intuition.  A blow to the neck of a totally healthy person with either a pocket-knife or a 20 foot long swords will kill that person equally dead in both cases.  The giant long sword has lots of advantages - reach, ability to parry, blade speed, difficulty to parry, and so on, but in the end it doesn't kill a person any deader than the pocket knife, it just makes it easier to get that killing blow.  It's not like people actually have ablative invisible armor that must be hammered to pieces before they can be hurt.  AFAIAC high damage for big weapons is just a gamist artifact of hit points that I don't mind discarding.

And for just liking to roll dice ... okay, you got me there.  If you like rolling more dice you should go ahead and keep your damage roll.

Quote from: Stephen Tannhauser on February 21, 2021, 11:13:39 PM
I've made it work for my own generic system homebrew, but that has the advantage that I stepped away from the "hit point total" model almost completely, where the multiplied totals are compared to set Wound Level thresholds instead of subtracted from a running total. If the goal is to preserve the feel of most D20 games that's less of an option.

I've used that approach before, and found quite a lot to like about it.  However it does create the possibility that a character will be taken out of action quite suddenly and unexpectedly.  While this is realistic and a good fit for some genres, it is not a good fit for the preference of many groups.  Have you found this to be the case as well?  And if so, did you try to ameliorate this issue? 

If your group likes math, combining the hit and damage via some sort of margin of success system can work; though I find it worked best with variant oWoD style mechanics where you have two axes to play with; accuracy affects difficulty, bigger attacks add dice; than a single axis system like d20 or nWoD/CoD/V5.

Actually, fixed-difficulty dice pools seem to handle it worse in my experience than die roll (be it 1d20, 2d10 or 3d6)+mod vs. TN ones as more dice in a pool at fixed difficulty increases resulting successes fairly linearly while also reducing the deviation (about two-thirds of all rolls of 10d at difficulty 6 will be between 4 and 6 successes and about 90% will be between 3 and 7 successes) meaning defense becomes rather binary too... either you have enough to avoid someone's attacks almost entirely or you're losing health every round.

The greater deviation of rolling 1-3 dice means sometimes defense will do something, sometimes it's not enough more often.

Either way though, if you're using a single-difficulty axis resolution mechanic, it will also work better if the system includes some sort of non-physical or very abstract hit points either in whole (strain in FFG Star Wars) or in part (Wounds/Vitality in d20 Star Wars) so that the ogre hitting every round represents you getting fatigued dodging his massive swings and not his clipping you with his massive club every round.

* * * *

All of the above said though, the majority of average people don't like complex math. I tested out a few such margin or success-based systems early on in developing my own system because, as someone who likes math and statistics, I didn't think something like determing margin of success would be a big deal. I similarly worked on an armor as DR based system too for similar reasons (a little subtraction is no big deal right?)

Boy was I wrong. The game slowed to a crawl because each added another operation to the resolution, but unlike a damage roll, couldn't be completed simultaneously or ahead of time.

Let's say your resolution system is one where damage is based on margin of success (lets use a basic weapon as multiplier; say x2) and is reduced by armor (i.e. armor as DR).

To resolve it you may only roll once and might do so ahead of time, but unless you know the target's defense ahead of time too you can't start calculating margin of success (subtraction) or damage (multiplication) and you have a third operation (subtracting armor DR from damage dealt) that can't be started until you know both the damage and the DR.

If your GM is keeping the defense and armor values secret, that's all math they have to do after your turn begins. If the system involves rolled defenses you can't even announce the defense value after the first hit so players can start doing the margin of success and damage multiplier math ahead of time.

Now this is something computers can calculate virtually instantaneously; which is why you see systems like this in video games all the time, but humans don't do even basic math functions nearly so quickly and that showed in my testing.

Conversely, in D&D you can roll your attack and damage die at the same time, then add your modifier to each. Then determining a hit is the most basic math function; comparison... if the attack result is greater or equal to defense number, you hit. Similarly if the hit check passes the damage is already known and is just subtracted once from the hit points.

If you're playing with adults whom you have reasonable trust of, then the rolling and addition can even be performed just ahead of the actual turn (as the previous action is being resolved) so that when the turn comes up you can just announce your attack roll. The GM then does the comparison operation (16 is greater than 14) and announces a hit or miss. If it's a hit then you announce your damage and the GM subtracts it from hit points and its on to the next action.

As glorious as damage based on margin of success could be in theory, in practice D&D's resolution is pretty much the sweet spot on the complexity scale for a general audience if my testing is any indication.

Now if your particular group enjoys MoS with damage multipliers and armor as DR, that's awesome. But if you're looking at releasing a commercial product, you need to be aware that you're marketing to a smaller niche and that complexity is a big part of the reason those systems never achieve the reach of something like D&D and that will limit your customer base to a level that may or may not be profitable for you.

Cue the story told in film-writing class about a successful indie film producer who only made films with mini- or anti-plots. He had a hard rule that his films could not exceed a budget of $2 million because at that level or less there would be enough of an audience (mini- and anti-plot are enjoyable to less than 10% of the population while more than 95% enjoy classical plot construction) that he would be able to return a profit to his investors and keep making more films... every dollar over $2 million increased the odds of it being a finacial failure which would mean investors would dry up.

Though the percentages aren't as extreme as the differences between mini/anti-plot and classical plot, math more complex than D&D is basically the game mechanical equivalent (the greater the complexity the smaller the audience).

You can do it, and there is a small audience for it, but keep an eye on your budgets if you hope to even break even.

Quote from: Chris24601 on February 22, 2021, 04:20:38 AMBoy was I wrong. The game slowed to a crawl because each added another operation to the resolution, but unlike a damage roll, couldn't be completed simultaneously or ahead of time.

This was my experience as well. And it didn't matter if 90% of the players could do the math quickly, all it took was one player that struggled with it (or couldn't care less) for the whole system to break down.

But there's another disadvantage that hasn't been discussed. Using a degree of success system forces the GM to tell the players the exact number the players need to roll for success. This adds another step in the process for the GM and requires the GM to run the game with a specific level of precision. The best systems are those where the GM doesn't need decide the exact number the players need to roll except in those cases where the player's roll is near the target number.

Quote from: hedgehobbit on February 22, 2021, 08:27:17 AM
But there's another disadvantage that hasn't been discussed. Using a degree of success system forces the GM to tell the players the exact number the players need to roll for success. This adds another step in the process for the GM and requires the GM to run the game with a specific level of precision. The best systems are those where the GM doesn't need decide the exact number the players need to roll except in those cases where the player's roll is near the target number.

Well, and I'd left it out because the specific topic is RPGs, but MoS systems also work fine in tactical wargames; which is probably why it worked okay in Heavy Gear, which from my experience was rarely played as anything but a wargame.

Another option that works well from wargames with fixed damage is systems like Battletech with specific hit locations. 10 points to an arm probably wouldn't penetrate the armor, 10 points to the head would not only punch the armor, but get a roll to see if equipment has been hit.

Hit locations could function even better in an RPG context if margin of success was used to narrow in on where you wanted to hit.

Say a base hit is a random roll for location, but you can add or subtract your margin of success from the location roll such that, at a wide enough margin, you could hit any location you choose.

Such a system would allow the base hit location to be rolled at the same time as the attack check too. The main drawback would be that everyone would need to fairly familiar with the hit location table so they know what sort of range their margin opens up. So, still more work than roll hit and damage separately, but would be a bit faster in that there's just figuring the margin and then deciding from the location range.

Another variant of that would be how the Western game Aces & Eights handled it. You had a silohette of a man with hit locations and a clear overlay with a targeting reticle denoted with rings of increasing numbers going in and the cards of a full deck going round the circle.

To attack you placed the overlay over the target, rolled the dice (2d6 if I recall), added your bonus and drew a card from a full deck. The hit occurred at the intersection of the number ring and line in determined by the card drawn. Better the roll the closer to your chosen bullseye while the card drawn randomized the direction of a miss.

It was definitely thematic, but I don't know that the resolution was particularly fast either as I only saw demonstrations of its use in the dealer room at Origins the year it came out and am largely going off memory on the resolution.

QuoteThis was my experience as well. And it didn't matter if 90% of the players could do the math quickly, all it took was one player that struggled with it (or could care less) for the whole system to break down.

TBH in such situation - it's best if GM does maths good.
Let's say you use percentage opposite rolls like in Warhammer. You say DM what is your result compared to your skill in melee, rest is DM's job to check result in such situation and announce result - not necessary in numeric value. And you have your Weapon + Strenght bonus to damage written down on CS.

QuoteUsing a degree of success system forces the GM to tell the players the exact number the players need to roll for success.

Not really. He just need to know it - he doesn't have to tell them.

QuoteThis adds another step in the process for the GM and requires the GM to run the game with a specific level of precision. The best systems are those where the GM doesn't need decide the exact number the players need to roll except in those cases where the player's roll is near the target number.

That's sort of ridiculous for me - it's way easier to take precise AC 23 let's say and judge rolls than... what? taking vague level of precision - how on Earth is vague math more useful?

The problem with putting all the work on the DM is that it puts all the work on the DM. They're already designing the adventure and running all the NPCs, now you want to add "rapidly perfrom multiple math operations per attack" to the required talent stack?

Few DMs are masochists; they're playing to have a good time too. If the system also requires them to speed run through an ((A-D)*W)-A=X equation to resolve an attack on each target*, then you're limiting your audience for your system to "groups with a GM who enjoys timed math challenges" and that's a pretty limited pool.

* Yeah, that's versus one target; multi-target attacks typically use a separate check (attack roll or save) for each target or else some sort of "divide successes between targets" (dice pool system) or "reduce check by X for each extra target" (some burst fire attacks) or "reduce damage value by distance" (some systems with explosions).

Any of above will result in the equation needing to be performed multiple times to resolve it. More power to you if you can find a GM who enjoys that, but you'd have to pay me to run a system like that.

Well that depends of system.
Considering D&D 3,5 yeah nope. But within limits of Warhammer - especially considering well way less HP and quite a lot options for nasty injuries beyond HP loss, I think I'd go for it.
But then I'd also gladly use Burning Wheel method of fight resolution, so I may be a bit of insane.

Quote from: Mishihari on February 22, 2021, 04:16:13 AMI've used that approach before, and found quite a lot to like about it.  However it does create the possibility that a character will be taken out of action quite suddenly and unexpectedly.  While this is realistic and a good fit for some genres, it is not a good fit for the preference of many groups.  Have you found this to be the case as well?  And if so, did you try to ameliorate this issue?

For me the issue was solved by putting in an option where people can dial the Wound Threshold levels up and down depending on the desired deadliness of their game. At the "Wildly Cinematic" level, for example, the threshold for a Critical Wound is equal to Vitality (a score from 1-10) x 16, which given a typical PC VTL of 6 means you have to achieve a DV (Damage Value) of 96.  This is, needless to say, very difficult to do with Base Damages generally ranging from 2 to 10 and Impacts (vs. an equally skilled foe) rarely over 6 at worst.  (There is also an option where you basically don't bother applying action penalties for any wound below Critical, which reproduces the "grind them down" feel of most hit-point-based systems.)

At the "Grittily Realistic" level, on the other hand, a Mortal Wound only has a threshold of (VTL x 10), meaning you only have to achieve DV 40 to take an average VTL 4 unarmoured man out in one blow, which happens about 25% of the time in a fight between equally skilled combatants, and also makes it quite mechanically feasible (if morally appalling) to beat an opponent to death with bare hands.

If you use the to-hit roll as also the damage, the system needs to be designed with it from the ground up. It would make a horrible house-rule.

I'm still not a fan generally for TTRPGs, as you lose a lot of granularity unless you want it to take far more time than just rolling and extra die in the same roll. It becomes difficult to have some characters/foes hit hard but inaccurately, as character optimization becomes all about jacking up the character accuracy.

Now - I DO like the idea of hitting easily causing bonus damage/effects, but I think that that's better expressed as a critical hit. In the system I've been working on, critical hits are done by hitting 10+ more than you need to hit the target. It's a Life Points/Vitality system, so the critical hit bypassing Vitality to deal damage straight to Life Points feels very different than just increasing the damage.

Rolemaster's attack tables do this though there's still a separate critical roll.

My own system uses "result" the low, high, or total dice of the attack roll is added to damage depending on the damage range of the weapon.

Quote from: BoxCrayonTales on February 21, 2021, 03:36:00 PM
So in D&D-derivatives combat generally involves two rolls: an attack roll and a damage roll. The result of an attack roll is a simple success, failure, or a critical hit (which doubles the damage dealt). The result of the attack roll otherwise has no affect on the damage roll.

Why not remove the damage roll and have the damage be determined by the attack roll? Are there any popular optional or house rules to this effect?

The best way to answer the question of "why not?" is to do it.

I've contemplated doing the following with my 1E game:

Damage is determined by how much the hit roll exceeds the minimum needed to hit. Subject to the particular weapon's min and max harm.

For example, broadsword vs S- or M-size creature does 2-8 damage. If I need a 14 to hit, it will do 2 damage on a roll of 14, 15, or 16, 3 damage on a 17, 4 on an 18, and so on. One caveat is I treat a natural 20 as if the die roll were '25' (this is how I simulate the six repeating 20's on the 1E hit tables without ever having to reference the hit tables). So on a 19, the broadsword would do 5 damage, but on a natural 20, it exceeds the number needed by 11, subject to the 8 damage cap on the weapon, so it does 8 damage on a natural 20.

This gives me wood for a few reasons. It saves me a die roll. It creates a bar-bell distribution (anti-bell curve) for the damage result with extremes being more probable than the middle, which I actually find makes more sense than a linear distribution or a bell distribution as it translates more directly into heuristics "light hit, heavy hit, mushy gray". Situational or skill factors that improve chance to hit (thereby decreasing the number needed to hit) come with the implicit tendency towards higher damage. And yet it still allows me to adjust damage independently of the hit roll. For instance, i can still do the x2 damage for a spear set to receive charge by just doubling the damage result. I don't have to go tinkering with the hit probability to make the math work out.

So why don't I just implement this immediately in my AD&D game without giving it another thought?

Well, first is it seems quicker and easier just to roll a separate damage die than to have to calculate the exact number needed to hit* and subtract that from the d20 roll, then double check to make sure it falls within the min/max for the weapon. Second, while I can adjust the damage without affecting the to hit probability, I cannot adjust the hit probability without adjusting the damage. There just very well may be circumstances, characters, skills, or magic items that would logically increase (or decrease) hit probability without adjusting damage in tandem. Like I may wish to distinguish someone who has a high hit probability but crappy damage vs someone who rarely hits but when they do, hold on to your ass.

So even though on the surface it seems to simplify things by saving the extra die roll and it seems more versatile and even "realistic" by making more accurate and highly skilled attackers also do more damage, in reality it makes things less simple and less versatile.

* It's a dirty little secret, but 80% of the time, when someone rolls the d20, it's either obviously high enough that it hits, or obviously low enough that it misses, without having to figure out the exact number needed to hit. Sure. Some people want to calculate that number each and every time. But as a DM, I have so many numbers coming at me throughout the game session that playing it fast and loose like this is a HUGE time saver without losing any fidelity.

Looking at the above posts, I suspect the difficulty has to do with how much math is involved.  My experience in this area is limited, but I can share what I have seen.  I've run the game I'm designing four times, I think, with its target audience, my 12 year old son and his friends.  Three times I GM'ed and once my son did.  The players don't have to do any math, they just roll.  If the roll is higher than the target the Narrator (GM) needs to do one subtraction or check if the margin is high enough to trigger a special effect.  It's run fast and smooth even with a 12 year old running the game.  After reading the above, though, I feel like I should do some additional testing to make sure this approach works okay before I proceed much further.

Edit:  I should add that the system is designed from scratch around the MoS mechanics; it's not something tacked onto a standard D&D version.

Lots of systems do correlate degree of successes to damage.  FFG's Genesys/Star Wars, Shadowrun, White Wolf, and the common factor for all of them is that they don't have thresholds that you have to roll over, any success is a hit, so you just count the number of successes and add that amount to the damage.  It makes the math very straightforward so you don't have to rely on a subtraction-deficient group member working out the numbers involved.