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Saturday, April 24, 2010

So, I Dreamed Another Dice Mechanic

One mechanic with which many gaming systems struggle is a good Armor Class/Damage Soak system. It's tough to balance something that offers some semblance of real life situations without it getting too complex to be viable. The real challenge is developing a system that encompasses the vast range of intensities that we humans utilize to murder each other. A good armor/damage mechanic should prevent a character from being capable of slowly whittling down a Main Battle Tank with a handgun and dogged determination. It should provide that a suit of armor doesn't become totally worthless the first time its damage value is depleted. It should allow body armor to reduce damage without necessarily negating 100% of it.

There are a lot of approaches to this, but I literally dreamed up a mechanic the other night. This is the second time I've had a dream about dice mechanics; if it happens again I might need to seek help.

Keep reading to see if I make any sense when I game in my sleep.

Basic scenario: Equal Damage and Armor dice

Damage and Armor are the two rolls, which are competitive, and can use any sort of dice. So, let's say a handgun has a Damage Rating of 3d6, and it is being opposed by an Armor Rating of 3d6. The results of individual dice are compared from highest to lowest, as follows:

Damage roll (3d6): 5, 3, 1
Armor roll (3d6): 6, 4, 1

Each Armor die matched or beat each Damage die, so the armor withstood the attack, completely. It was a glancing blow, hit a hard point, was absorbed by an energy field, or repelled by a psychic mind field. In any case, the Armor won.

Another round, and another shot:

Damage roll (3d6): 5, 4, 2
Armor roll (3d6): 4, 4, 3

One die of Armor was defeated, allowing Damage to pass through, and the defending character takes damage. Further, the armor is now damaged, and loses the defeated die. The next shot will be 3d6 vs 2d6.

Damage roll (3d6): 3, 2, 1
Armor roll (2d6): 5, 5

You only match up as many dice as the defender has available, so in this case, the low die of the Damage roll is discarded and the Armor holds.

Advantage to the defender

I see this system as normally having Armor Ratings higher than Damage Ratings, so a battle matched in that way would look something like this:

Damage roll (3d6): 5, 5, 3
Armor roll (5d6): 6, 6, 3, 1, 1

Match up the individual die rolls, one-to-one, and the 6-6-3 of the Armor defeats the 5-5-3 of the Damage, nullifying any potential harm. For the next shot:

Damage roll (3d6): 6, 5, 4
Armor roll (5d6): 6, 3, 3, 2, 2

Damage wins the 5-3  and 4-3 matchups, delivering damage to the defending character, and reducing the Armor Rating from 5d6 to 3d6.

Scaling dice

One more wrinkle before you go cross-eyed with my incredibly long and boring post. Not all Damage and Armor are made equal. Some weapons are of low-power and, in addition to having relatively few dice to roll, may only roll a 4-sided dice. A powerful cannon from an armored vehicle might roll 10-sided dice for damage, and roll far more dice as well. Likewise, personal body armor might have 2d6 of protection, while the main body of a battleship would have 50d20.

A square-off between a shooter with a plasma rifle versus some poor native wearing armor made of leather and bone might look like this:

Damage roll (6d8): 8, 6, 6, 5, 2, 1
Armor roll (2d4): 4, 4

Even a perfect roll couldn't save the native, and he sees his armor destroyed and takes what will likely be enough damage to vaporize him.


In this system, think of the vast number of ways that Damage and Armor could be customized. Want a weapon with pinpoint accuracy and penetrating power? Try a 2d10 laser rifle against that basic 3d6 armor. Maybe the personal body armor offers great coverage but is lightweight, resulting in a rating of 5d4. How important would a Skill Check or Feat be if it provided a simple +1 to a single die of the attacker's Damage Rating. A character's impressive Healing Factor could be represented by the renewal of one die of Armor Rating each round.

Lots and lots of possibilities, there.

And so on

You get the idea. This is way too much number-crunching for a Saturday morning, so I'll leave it there, for now. It has a lot of kinks to be worked out, but I think the system has some promise.

That is, of course, if someone didn't already write this and I'm now plagiarizing in my sleep.

UPDATE: Find more thoughts and discussion in this follow-up post.


-Mark said...

Do hate to tell you this, but it looks familiar. Can't recall where I saw it from, but the matching dice does ring a bell.

Jason Richards said...

It's similar in some ways to Risk, which might be what you're thinking of. I've long wanted to take a stab at that sort of dice mechanic, which is probably what it was doing in my head to begin with.

It very well could be duplicated in some other game. I've just never played it.

EvilTwinBrian said...

I'm not as well versed in RPG mechanics, but the only thing I see that may turn some off is the time needed to incorporate this. On a basic mechanics level it's similar to a damage soak type of roll (like in D6 Star Wars or Shadowrun), so I'm sure it will work well in some situations, but adding it on top of an existing system may slow things down a bit (like a system that has an armor rating system to reduce or prevent damage, or one that allows the armor to take a certain amount of damage).

Also a pro and con of this mechanic is the seeming realism of it. Armor isn't meant to stick around encounter after encounter (I'm sure cops aren't wearing the same vest once it's taken a bullet), but that adds logistics that the players may not want to deal with. Some may really dig that, though.

Helmsman said...

Not too bad. Your numbers seem pretty consistent with the performance expectations of modern armour. My only concern is that combat is going to be 3 rolls (to-hit, to-damage and to-soak, assuming there isn't going to be a to-dodge roll in there too) and dice shuffling and comparisons to resolve a single attack. That makes for pretty slow gameplay.

As for concerns of if you're doing something that's already been thought of or not, don't worry about it. No one's done anything new with dice since the age of the ancient greeks and it's pretty much impossible to patent or copyright a dice mechanic. RPG companies steal good ideas from each other all the time. Holding yourself back from designing a dice mechanic because something like it's been done is like stopping because XP is a term that's already in use, or that the concept of Advantages and Disadvantages as things to purchase for characters is already in-use. It's not something you need to be concerned about.

Jason Richards said...

Good comments, all around. If this were to be instituted as a fresh mechanic system (I wouldn't try to tack it on top of something else already in place), I'd need to work out a way for this one Damage/Armor roll to also include the actual damage dealt.

In my original post, I actually included something to that effect, but I edited it out before posting because it didn't work. My first thought was that in a contested roll, any succeeding die would be the damage. So, in a 3d6 vs 3d6 roll of:

Damage: 6-5-4
Armor: 5-5-5

the damage dealt to the character would be 6, for the one die that defeated the armor roll. Of course, that doesn't work, because what if your Damage/Armor stacked up like this:

Damage: 6-6-6-6-6-6-6-6
Armor: 1

Clearly you couldn't go with only 6 points of damage. Those other dice need to fit in there, somehow.

Like I said, I'm still working it out. Ultimately things like this will need to be addressed, and I'll need to sit down with the ol' calculator and spreadsheet and run some statistical models to really iron it out, but that's WAY down the line.

Keep the comments coming!

Helmsman said...

You need to decide how you're going to model actual trauma in your game. Are you going to go with a hit-points model where you have a number and as you get whittled down you die, or are you going to go for hit locations blood loss and realism? Hit points are nice because they're easily scalable from bunnies to dinosaurs, while the merits of hit location and a more realistic representation really shine when you're dealing with cybernetics and body replacement. But really, that's the only reason why you'd want it. Hit location in a fantasy game is just pointless bloat in my opinion... or worse because it sacrifices fun by creating too much of a possibility for easy unsatisfying deaths because the designer wanted realism.

However you seem to be wanting a game that does armored vehicles so I have to assume you're going to the futuristic end of modern, so my recommendation is to include hit locations. You can tie that into a to-hit roll fairly easily. The next thing you can do to keep gameplay fairly quick but keep your realism high is create a two-tier type of damage.

Consider: A punch can have more actual force than a bullet when it hits it's target, yet the bullet does more damage because it penetrates skin. Skin is armour as well, so the penetration of an attack clearly matters. But the width and bredth of the damage matters as well as the depth, so how do you model that?

Basic physics. It's a matter of volume, depth x width x height. So you give your weapons both penetration and damage, and you make the results multipliers of each other to determine total damage. Then you make armour suck points out of penetration (which is what it does) even if it penetrates it might actually slow the attack's force enough so that it won't be as traumatic. You cap the penetration result according to the size of the target to represent the attack creating an exit wound.

An even easier way to represent this is to have penetration and damage rolled and the lower of the result is the one counted but this requires you to have some pretty canny damage tables calculated just right or the numbers start to skew in ways that aren't ideal, though you can fiddle with the curves by using multiple dice and calculating the results in different ways.

Brian said...

Seems a little too much for me. What I've done is simply take the MDC total of the Main Body and divide it by 10. That's the damage reduction. For simplicity sake the armor continues to absorb the same amount until its destroyed.

So pistols and rifles generally will not be able to destroy your shiny new 40 million credit robot vehicle, at least not very easily. An increase in robot/vehicle weapons damage was also implemented.

Jason Richards said...


I find that one of the easier mechanical ways to control things in a "realistic" fashion without getting into the heavy math and physics is to use the setting to dictate the physics that will be used. This doesn't work quite so well in modern games, where we already understand the world and how it functions, but can work in fantasy or, especially, science-fiction and other high-tech realities.

Taking this proposed mechanic as an example, let's say you have a setting where you have "blaster" type weapons as the standard, giving a typical weapon a rating of 3d6. As an alternative, you might have a highly-focused laser that is narrowly focused with high penetration value, but less overall destructive potential. This weapon might have a rating of 2d8, which is more likely to penetrate armor, but has less overall destructive capability.

Just spitballing here, obviously, but hopefully that makes sense. Another method to handle hit locations with a technology that is grounded in the mechanics of the game is to make standard armor a force field sort of device rather than traditional body armor, thus eliminating the need for hit locations in your basic combat scenario.

In any case, you raise good points. A game designer really has an obligation to ensure that the mechanics and the setting get along, which is one reason I suggest that so-called "universal" rulesets often have some pretty serious holes.


That doesn't address the fundamental issue of soak/penetration, though. MDC is fine for what it is, and your fix is a common one. Heaven knows that MDC in Rifts is not a good or reasonable system as written if put under any scrutiny at all. The sort of adjustment that you mention, effectively widening the gap between personal and vehicle level weapons and armor, is a good one.

I don't intend for this to be used in any Palladium game, though. Palladium has its system and it works for them. My thoughts, or dreams as the case may be, were that this would be something used all on its own, not in conjunction with another system.

Helmsman said...

Your 2d8 example is very valid though I'd say it still depends on how you're going to model the actual damage and trauma when the blaster bolt hits the soft squishy human parts. My suggestion worked for me because I was actually trying to model blood loss and the debilitation of tissue and bone damage. I think with those lofty goals in mind it's a pretty elegant solution, but if you're going to stick with tried and true hit points mechanic as more of a homogeneous representation of health, then your example will certainly work out.

L7sys said...

It sounds like there's something good here, especially how you have it applying to penetrating vs radius damage.

Couple things to think of how your idea applies in further scenarios (you may have already through of it) - If the weapon throw is larger than the armor throw (3d4 weapon vs 2d6 armor), you could incorporate in "force" which basically knocks you down. Like getting hit with a 2x4 if you're wearing platemail... but if it's a lot greater, it can knock you over or throw you in the air (like an 8d4 bomb vs 2d6). Penetrating weapons (1d10 vs 2d6) would just go right through you. I think some weapons specify this in the descriptions, but this implies it right in the roll and could make it easier to understand and apply to advanced scenarios. It also takes into account wearers skill or weight of the armor. For example, no beginner would have access to 5d6 armor, but even if it's lightweight 5d6 magic armor, if a 6d4 bomb goes off the skilled wearer might just fall to a knee where a beginner in 2d20 armor would get thrown across the room. Or wear insane 10d4 armor and never fall over, but it'd be worthless against a knife. And just like you said, even if you got stabbed, the armor would still be useful if a bomb went off.

Easy to understand.

Someone mentioned trauma. Battletech had a type of armor/damage assessment, but for people, trauma isn't helpful. It doesn't take much to incapacitate a soldier (just break their knee and they'll be immobile and too distracted with pain to concentrate on effective targeting, let alone trying to swing a sword or cast magic). Plus it slowed the game down so much it was hard to be maintain a pace.

Anyway, in battletech, if a particular shot or infantry-placed explosion penetrated the armor it wouldn't necessarily deplete the armor for that location, but it would receive a little bit of damage. Instead you rolled again for if/how it impacted the internal structure and chassis (weapon system, engine). Each had a related effect, such as you could puncture a coolant line so the energy weapon could still fire but not as often. Or it would have no effect. Your playersheet had a blueprint of external/internal damage. Weapons also had recoil, so if you had a low piloting skill and moving fast and tried to shoot, you'd knock yourself over. By the end of a battle you could be limping, jammed facing a particular direction, or blind because the cockpit got cracked. I never really enjoyed playing at that level because it took 7 rolls for every weaponshot (multiple weapons). But of course, it didn't stop me from taking advantage of the inherent flaw with the game mechanics, to the frustrated dismay of many people.

Or make it as complicated as you want and make an iphone app to roll and tally.

Stuart said...

I think your 6-6-6-6-6-6-6-6 versus 1 should resolve this way.

6 points for the penetrating die vs. the 1 + 1 point for every extra unopposed die. + 7 total 13 points damage. I would extend this to extra dice even if no penetrating dice were rolled. r.g. 5-4-3-2-1 vs. 6-5-4
None of the attacking dice penetrate but the target takes 2 points for the extra dice.

Just my initial thinking. I like the system

Phlod said...

This is how I did it. It's eerie too, I just came up with this idea 3 days ago, also after playing some Risk. I've never been to yer site until yer article on Rifts Mega Damage hit the RPG page of Reddit, so I find this coincidence a little creepy. In a good way. :)

Anyway, this is how I broke it down.

First assuming both Attacker and Defender are rolling d6s.

Attack - 5 dice 6,5,5,3,1
Defense - 4 dice 4,2,2,1

First you do the cancellation step. Defender cancels attacker's 3,1 leaving 6,5,5. Now, add both Attacker and Defender's dice together, respectively. These are the Attack Score, and Defense Score for that round. Then, subtract the Attack score from the Defense score to get the Margin of Success or Failure. I.e. Attack 6+5+5 == 16 Defense 4+2+2+1 == 9. 16 - 9 == 7 Margin of Success. The MoS is called the Weapon Damage Bonus, and is added to the base Weapon Damage number based on the weapon wielded. Assuming a Sword has a WD of 4; 7 + 4 == 11 Damage to the Defender.
(Had the attack ended with a Margin of Failure, the Defender Parried, Dodged, or Blocked the Attack outright, and no damage is taken.)

I made it so each piece of armor and defensive enchantment has a Passive Defense score. Subtract the PD from the MoS of the attack (armor soaks damage). Subtract 1 from this score each time it gets hit, if you like, to model armor damage.
So, assuming Chainmail has a PD of 5, (and that yer wearing Chainmail), 11 - 5 == 6 Damage to HP Pool, or whatever yer system uses.

A significant MoF on an attack (over a certain threshold #), would qualify for a Riposte strike, which simply uses the MoF minus the Riposte Threshold as the Weapon Damage Bonus.

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