Let me start off by saying that this is my second post on the forum and the first was just an introduction. I am not sure this thread is in the right place, and if it isn't please let me know where it should be.

I'm currently in college, taking courses for a certificate in game design. In the mean time, I've got a rule set and a number of settings for possible future games. Right now, I'd like to focus on the armour system in this rule set, and the penetration system that ties into it. I'm looking for feedback on this system, and more importantly things I could add to this system.

Basic overview:

This armour system includes three major parts: damage division (DD), damage reduction (DR) and resistance (RE). Each of these is specific to a single damage type. These three parts are all countered by a factor of the attack called "penetration." (P) There are other special factors for some damage types, such as "temperature" for thermal damage, "current" for electric damage (effectively the same thing as temperature) and "piercing" for some incisive weapons. This system is intended to not only determine how much damage (if any) an attack deals through armour, but also to determine if an attack will pass through a target to hit objects on the other side of them, as well as how much penetration and damage it will have if it does.

Damage Division:

DD is the primary defence against most attacks, and the only thing that actually reduces the penetration of an attack that defeats it. Damage division is a direct counter to penetration itself. Penetration is divided by DD to yield a number called "penetration factor" or "PF." PF is a number by which a weapon's damage is multiplied, with some restrictions. If penetration factor is at one, a weapon deals normal damage. Any less, it deals partial damage. (For instance, a PF of 0.55 means 55% damage before DR and RE.) Any more, and the weapon deals full damage and continues on to damage objects behind the target, with its penetration reduced by the perforated target's DD. For instance, a 9mm bullet from a pistol might have a penetration of 0.95, and a human adult male might have a DD of 0.6. Ignoring natural armour, (which would only be PDD 0.1, PDR 1 and PRE 1% anyway) the pistol would deal full puncture damage (160) and continue on to hit other targets with a penetration of 0.35. A #1 buckshot pellet from a 2.5" shell, on the other hand, usually only has a penetration of 0.33, and will deal 55% puncture damage (120*0.55=66) and fail to over-penetrate.

Damage Reduction:

DR is the secondary defence against most attacks, being both second in order and second in importance. It is a simple reduction effect, and is subtracted from the damage. It is also subtracted from the energy (see energy transfer below) of the attack, if it is of the same type. This loss is permanent, and does not apply only to the target the DR belongs to. So a bullet with 160 damage that comes up against a DR of 10 will deal 150 damage to the target, and will only have 150 damage against the next target.

Damage Reduction and Penetration:

Penetration may have a different effect on DR, depending on damage type. For kinetic and miscellaneous damage types, penetration divides DR. So a penetration of 2 means an attack gets half effect from DR, and a penetration of 0.5 means double effect. For energy and chemical damage types, penetration subtracts from DR by ten times value. So a penetration of 2 mean DR is 20 points lower, and a penetration of 0.5 means DR is 5 points lower. This cannot reduce DR below 0.

Resistance:

RE is the tertiary defence against most attacks, last in order and least in importance. It is a simple resistance effect, a percentage removed from the damage. It is not subtracted from the energy (see energy transfer) of the attack, even if it is of the same type. It is also permanent, and will impact the amount of damage dealt to future targets.

Resistance and Penetration:

Penetration may have a different effect on RE, depending on damage type. For kinetic and chemical damage types, penetration subtracts from RE for ten times value. This cannot reduce RE below 0. For energy and miscellaneous damage types, penetration divides RE.

Energy transfer:

All weapons have at least one form of non-penetrative damage, such as the concussive damage (K) dealt by all kinetic weapons, even if their primary damage type is a penetrative damage type. If this is their only damage type, it performs as normal. If it is not, it is dealt to every target the weapon hits, and is taken from a pool called "energy." (E) A fraction of the pool is dealt as damage equal to the square root of the fraction of the weapon's total penetration used on the target. So if, for instance, a bullet with a KE of 50 and a penetration of 0.95 hits a target with a DD of 0.6, it will deal 40 concussive damage, and will have a KE of 10 afterwards. 50*(0.6/0.95)0.5=~40. This damage acts as its own attack, and will continue onward to hit other targets independently. So, for instance, a bullet stopped by armour might still damage the target, as concussive damage conducts through it.

Body, natural armour and armour:

These values above are used for an object itself, but also for two layers in contact with it. These are natural armour and armour. These are treated as separate objects by the penetration system, although not by the engine, and must be penetrated by each damage type to damage the next. Armour comes first, if it is present (and armour may have multiple layers) followed by natural armour and finally the body of the object. After this usually comes natural armour again, followed by armour one last time before the projectile is free, as a target is usually armoured on both sides. On its way out, any energy transfer that goes through the current layer still damages the target, even though the weapon is heading the other direction.

If you want examples, feel free to ask.

Wow, this is quite a lot to take in and I must say, it seems promising on first read.

I have a few remarks:

For energy and chemical damage types, penetration subtracts from DR by ten times value. So a penetration of 2 mean DR is 20 points lower, and a penetration of 0.5 means DR is 5 points lower. This cannot reduce DR below 0.

What's your thought process here and why does the effect of penetration on DR differ so much depending on the type of damage?

Have you thought about factoring in the angel of penetration, with projectile damage, this is a huge factor.

The sine of the angle of penetration could be a multiplier for the penetration and for kinetic damage it would also be a multiplier of the concussion damage.

I'm not sure if you have anything in place to calculate whether an attacking bounces off the armor, but it could be very interesting to see a powerful attack bounce off a set of armor with high DD and hit another target.

The calculations here should be rather simple, you do a check of the P multiplied by the sine of the angel of the P against the DD. If it bounces, you calculate the concussion and the new direction and KE of the projectile.

It seems that the system you have in place now doesn't allow for dinging as the PF is always a positive number.

In any case, this is very interesting and a few examples would be nice.

Wow, this is quite a lot to take in and I must say, it seems promising on first read.
I have a few remarks:

What's your thought process here and why does the effect of penetration on DR differ so much depending on the type of damage?

Frankly, I thought about it for a while and decided I wanted to do it two ways for DR and RE, and didn't want any two categories to be the same because I wanted the categories to mean something. As for which got which, it made sense to me at the time, and some still make sense. For instance, penetration for kinetic weapons more or less amounts to momentum/area. (Or, for concussive damage, it's just pressure.) So a kinetic weapon with double penetration either has twice as much momentum and would be slowed down half as much by any defence, or it's over half the area and would only encounter half as much resistance. For an energy weapon, penetration is also a factor of concentration, but they don't have any momentum to keep them focused and would diffuse. So any amount of extra concentration would only do so much to reduce the effect of a defensive measure before the energy spread out.

Have you thought about factoring in the angel of penetration, with projectile damage, this is a huge factor.
The sine of the angle of penetration could be a multiplier for the penetration and for kinetic damage it would also be a multiplier of the concussion damage.
I'm not sure if you have anything in place to calculate whether an attacking bounces off the armor, but it could be very interesting to see a powerful attack bounce off a set of armor with high DD and hit another target.
The calculations here should be rather simple, you do a check of the P multiplied by the sine of the angel of the P against the DD. If it bounces, you calculate the concussion and the new direction and KE of the projectile.

[/quote]
Well, here I'm just not sure the engine can handle it. Even if it did, it's a bit harder to code and it's yet another thing for the player to keep track of. (The rules are complicated already.) That's not a "no," just a "maybe."

It seems that the system you have in place now doesn't allow for dinging as the PF is always a positive number.

Well, that's not quite true. Even if you do always get some penetration on an object, this comes before DR and RE have their say. If there's significant DR, you'll need a certain amount of penetration not to be left dealing 0 damage.

In any case, this is very interesting and a few examples would be nice.

I'll try and run the gambit here. Five weapons, five targets. Sticking to smaller weapons (infantry weapons and one moderate-power spell) because that's the most relevant, but I'll go all the way up to tanks on the side of the target. (If it's of any use, it'll be to show what these things can't do.) I'll use weapons from multiple genres, but stick to five example targets that are real-world, generic or not too terribly different from their real-world equivalent.

Terminology notes: Puncture damage is abbreviated as "L." This stands for "laceration." This is to avoid confusion between it and penetration in its abbreviation. This is a recent change. And by "recent" I mean "I realized there was an issue, and changed it as I was writing this." Concussive damage is abbreviated "K" as in "Kinetic" and thermal damage is abbreviated "X" as in "Exothermic" or "N" as in "Endothermic," depending on whether it is high or low temperature that is causing the damage. The other damage types are incision (I), bludgeon (B), electric (E), chemical (C) and ionizing (R), but none of those are relevant.


Target A: Bare human torso: (Adult, base stats, no relevant bonuses)
LDD 0.6, LDR 10, LRE 10%, KDD 0.1, KDR 2 4, KRE 2%, XDD 1.1, XDR 10, XRE 10%
Skin is not counted in-game without investing feats, perks and/or having a special species ability because it wouldn't do a damn thing.

EDIT: I initially wrote 2/2%, but that's not correct. Also, RE has been removed entirely since this was written.

Target B: Combat Armour: (Medium armour, ballistic, basic quality, not on the plate)
LDD 1, LDR 10, LRE 10%, KDD 0.1, KDR 1, KRE 1%, XDD 0.1, XDR 10, XRE 10%

Target C: Thick generic automobile door: (military truck, steel, manufacture date ~2015)
LDD 3, LDR 30 60, LRE 30%, KDD 0.3, KDR 3 6, KRE 3%, XDD 0.15, XDR 30 60, XRE 60%
Special: Double layered, must be penetrated twice to pass through.

EDIT: This is metal armour, so it has double DR. I forgot that the first time I did this.

Target D: HMMWV door: (without up-armouring, manufacture date ~2015)
LDD 15, LDR 150 300, LRE 150%, KDD 1.5, KDR 15 30, KRE 15%, XDD 0.75, XDR 150 300, XRE 150%

Vehicular composite armour, which is like metal armour in its stats but much more so. The stats were mostly right, but the DR was wrong.

Target E: U5A1 Whiplash LST frontal aspect: (without up-armouring, manufacture date ~2015)
LDD 50, LDR 500 1000, LRE 500%, KDD 5, KDR 50 100, KRE 50%, XDD 2.5, XDR 500 1000, XRE 1000% (It is not *technically* invulnerable, but for our purposes it might as well be.)

EDIT: All of the following calculations have been fixed. There is no strikethrough text for the old values because it was screwing me up.

2.5" #1 buckshot (7.62mm ball)
L 120, KE 15, P 0.33 (Very strongly under-powered, but depending on what weapon you're using you may be firing anywhere from 7-15, and a common 12 guage fires 10. Still shit against armour.)
Velocity is ~340m/s, and if the engine will allow it, this will actually decrease in proportion to its loss in penetration as it flies and each time it penetrates a target. Then, of course, there's gravity. Not a simple point & shoot game if you're at any significant range.

A:
L. 0.33/0.6=0.55, 120*0.55=66. 10/0.33=30. 66-30=36. 36 puncture damage.
K. 0.33/0.1=3.3. (P>KDD, full damage. New P is 0.23.) 4/0.33=12. 15-12=3. 3 concussive damage.
Total 39 damage.

B:
L. 0.33/1=0.33, 120*0.33=40. 10/0.33=30. 40-30=10. 10 Puncture damage. (To the armour itself, not the wearer. The wearer is not punctured.)
K. 0.33/0.1=3.3 (As above, full damage. New P is 0.23.) 1/0.33=3. 15-3=12. 12 concussive damage. (The wearer will take 12 K with 0.23 P. If they are as above, after all resistances they will take 3 concussive damage.)
Total 22 damage.

C:
L. 0.33/3=0.11, 120*0.11=13. 60/0.33... We can stop here, can't we? We know it'll be 0 puncture.
K. 0.33/0.3=1.1 (Basically meaningless 0.1p left.) 15*1=15. 6/0.33=18. 15-18=0. 0 concussive damage.
Total 0 damage. Congrats, you chipped the paint. Actually, you didn't even manage that.

D:
L. 0.33/15=Oh, who cares? We know where this ends. 0 puncture.
K. 0.33/1.5=0.22. 15*0.22=3. 30/0.33=90. I'll just stop here, where the DR is presently 30 times greater than the damage. 0 concussive.
Total 0 damage. Not so much as a scratch.

D tanked it. E is much tougher than D. Not going to bother, we know how it'll end.

9x19mm Parabellum, (Jacketed, from a Glock 17)

L 160, KE 50, P 0.95 (Still a tad under-powered, but it's an acceptable cost for using an accurate, reliable weapon with a large magazine. The G17 is such a weapon.)
Velocity is ~360m/s. Better penetration is mostly due to the bullet's shape and metal jacket. It also flies straighter for the same reason.

A:
L. 0.95/0.6=1.58. (P>DD, bullet will over-penetrate with a new P of 0.35) 10/0.95=11. 160-11=149. 149 puncture damage.
KE. PF=1.58, 1.580.5=1.26. 50/1.26=40. 40 K, leaving 10 KE.
K. 0.95/0.1=9.5. (Yes, this has to do a DD check as well.) 4/0.95=4. 40-4=36. 36 concussive damage.
Total 185 damage.

B:
L. 0.95/1=0.95. 0.95*160=152. 10/0.95=11. 152-11=141. 141 puncture damage.
K. 0.95/0.1=9.5. 1/0.95=1. 50-1=49. 49 concussive damage.
Total 190 damage.

C:
L. 0.95/3=0.32. 0.32*160=51. 60/0.95=63. 51-63=0. 0 puncture damage.
K. 0.95/0.3=3.2. 6/0.95=6. 50-6=44. 47 concussive damage.
Total 62 damage. (Nice dent.)

D:
L. 0.95/15=0.06. 0.06*160=10. 150/0.95=158. Stopping here, it's 0 puncture.
K. 0.95/1.5=0.63. 0.63*50=32. 30/0.95=32. 32-32=0. 0 concussive.
Total 0 damage. (The crew is laughing at you.)

E: It's a pistol. You're shooting a tank. It does exactly what you'd expect.

5.56x45mm NATO (Spitzer, boat-tailed, from an M16A4)
L 60, KE 180, P 4.5 (Well, it penetrates, but it couldn't stop a man if you had him sedated first. Alright, that's quite a bit of hyperbole, but the stopping power is terrible.)
Velocity is ~950m/s. Not the fastest projectile here, but it's more than fast enough for most purposes. Derives its penetration from its shape, which is also responsible (along with a tiny bore) for its lack of stopping power.


A:
L. 4.5/0.6=7.5. 10/4.5=2. 60-2=58. 58 puncture.
KE. 7.50.5=2.74. 180/2.74=66. 66 K, leaving 114 KE.
K. 4.5/0.1=45. 4/4.5=1. 65 concussive.
Total 123 damage.

B:
L. 4.5/1=4.5. 10/4.5=2. 60-2=58. 58 puncture.
KE. 4.50.5=2.12. 180/2.12=85. 85 K, leaving 95 KE.
K. 4.5/0.1=45. 1/4.5=0. 85 concussive.
Total 143 damage. (And yes, you get hit with 85k from this, and whatever energy you soak in from the bullet going through you. The armour actually resulted in you taking more damage. Way to go armour.)

C:
L. 4.5/3=1.5. 60/4.5=12. 60-12=47. 47 puncture.
KE. 1.50.5=1.22. 180/1.22=148. 148 K, leaving 32 KE.
K. 4.5/0.3=15. 6/4.5=1. 148-1=147. 147 concussive.
Total 194 damage. (Finally, something that inflicts noticeable damage to a vehicle, and penetrates.)

D:
L. 4.5/15=0.3. 60*0.3=18. 300/4.5=67. 0 puncture.
K. 4.5/1.5=3. 30/4.5=7. 180-7=173. 173 concussive.
Total 173 damage. (You just left a nice, big dent. They really should have gone for the up-armour kit.)

E:
L. Not going to bother, we know where this ends. 0 puncture.
K. 4.5/5=0.9. 0.9*180=162. 100/4.5=22. 162-22=140. 140 concussive.
Total 140 damage. (Don't think that's hurting it. It's a tank. It has tens, sometimes hundreds of thousands of hit points on each part. You'd need a torrential downpour of bullets to inflict noticeable damage.)


300kj pulse laser (300mw/1ms, 1cm beam, 800nm, M3A2 laser carbine)*
X 300, K 300, P 6 2 (Great penetration there, and no complaints about the stopping power. Lethality is poor, due to its damage types being thermal and concussive.)
Hitscan. At least as far as it matters.

EDIT: The original "6" was incorrect. It came from one of my old notepads, in an older system. 2 is the correct value for all personal, weapons-grade lasers. (1 for toys, 2 for personal weapons, 3 for heavy AP weapons, 4 for AM weapons and 5 for AT weapons.)


A:
X. 2/1.1=1.81. 10-20=0. 300 thermal.
K. 2/0.1=20. 4/2=2. 298 concussive.
Total 598 damage.

EDIT: There was a serious error somewhere in here. I'm not sure where it started or how it happened. Doesn't really matter now.

B:
X. 2/0.1=20. 10-20=0. 300 thermal.
K. 2/0.1=20. 1/2=1. 299 concussive.
Total 599 damage.

C:
X. 2/0.15=12.33. 60-20=40 260 thermal.
K. 2/0.3=6.67. 6/2=3. 300-3=297. 297 concussive.
Total 557 damage.

D:
X. 2/0.75=2.67 300-20=280. 300-280=20. 20 thermal.
K. 2/1.5=1.33. 30/2=15. 300-15=285. 285 concussive.
Total 305 damage.

E:
X. 2/2.5=0.8. 0.8*300=240. 1000-20=980. 240-980=0. 0 thermal.
K. 2/5=0.4. 0.4*300=120. 100/2=50. 120-50=70. 70 concussive.
Total 70 damage. (You dinged it. That's about all you accomplished.)


Scorching Ray (base stats, 50% efficiency, no relevant bonuses, non-divine caster)**
X 250, K 125, P 1.25
Velocity is ~160m/s. Didn't think spells would be hitscan, did you?

A:
X. 1.25/1.1=1.14. 10-13=0. 250 thermal.
B. 1.25/0.1=12.5. 4/1.25=3. 125-3=122. 122 concussive.
Total 372 damage.

EDIT: Something got fucked up somewhere. KDR was registering as an absurd 10 points. Fixed now.

B:
X. 1.25/0.1=12.5. 10-13=0. 250 thermal.
K. 1.25/0.1=12.5. 1/1.25=1. 125-1=124. 124 concussive.
Total 374 damage.

C:
X. 1.25/0.15=8.33. 60-13=47. 250-47=203. 203 thermal.
K. 1.25/0.3=4.17. 6/1.25=5. 125-5=120. 120 concussive.
Total 323 damage.

D:
X. 1.25/0.75=1.67. 300-13=287. 250-287=0. 0 thermal.
K. 1.25/1.5=0.83. 125*0.83=104 30/1.25=24. 104-24=80. 80 concussive.
Total 80 damage.

EDIT: Once again, something was very wrong here. How did I get "133" from 150-13? Fixed now.

E:
X. We already know how this will end. 0 thermal.
K. 1.25/2.5=0.5. 125*0.5=63. 100/1.25=80. 63-80=0. 0 concussive.
Total 0 damage. (Cast to your heart's content. The tank doesn't give.)


*From a near future setting with significant alternate history. Issued to some designated marksmen from 2018-2032, has a 10-shot power cell and a 6-second recycle time. Unreliable, slow to fire, low capacity, weighed 6kg and each power cell weighed another 1.5kg, making it possibly the least practical infantry weapon since the Chauchat. Add on low lethality rates due to its primary damage type not causing much bleed, and it's a wonder it survived long enough for better models to be produced. Still better than the previous model, which was even less reliable and held half as many shots.

**From a fantasy setting in the same universe. This spell is of Vancian preparation and usage, despite being a natural feature of the inhabitants. It uses a combination of incendiary fluid and directed infrared radiation to create a focused blast of super-heated gas. In this case, the burst of heat is ~2000k. Most casters can use spells of this grade 2-3 times each day, although they do tend to cause themselves considerable harm doing so.

It all looks rather realistic and your explanation for the different effects of Penetration on DR is rather satisfying, I hadn't thought about it being concentration of energy or so.

As for the dinging attacks, something feels off about DR being required to ding an attack, it just feels like just DD should be able to do it.

Calculations would really be rather basic, what you'd need to do is find the normal of the polygon the projectile hits, get the velocity vector of your projectile, project that vector onto the normal. Subtract the result twice from your original velocity and you have the new velocity vector of your projectile.

Basically.

Anyway, this is really interesting, but it does look very complicated and I feel it would be a tad hard to design a game that makes these feature really obvious to the player.

Maybe you have some ideas already?

It all looks rather realistic and your explanation for the different effects of Penetration on DR is rather satisfying, I hadn't thought about it being concentration of energy or so.

Well, at least that's the idea.

Anyway, this is really interesting, but it does look very complicated and I feel it would be a tad hard to design a game that makes these feature really obvious to the player.
Maybe you have some ideas already?

Well, this is designed for RPGs. So stats being visible from the inventory menu wouldn't be strange, but what I intended to do was give the player an item description to start with, some simple information if they make a skill check and much more information (down to the individual DD/DR/RE values) if they make a much higher check.

So, for instance, a character in a fantasy (one of the ideas in the works is a fantasy arena RPG) might pick up a suit that reads "Cubus Leather Brigandine" and at first only get a description about these brigandines being manufactured by cubi from the leather of plain raiders (a flying electric creature that looks kinda like the Jersey Devil) and its reputation for flexibility and all-around solid protection. The stats available would be weight and relative condition, the class of apparel, (light armour) the material type (fabric) and the quality of the material (+2.) With a skill check, they might ascertain that this piece is a shoddy knockoff made from the same material but without the proper treatments, and that it is old and worn. The stats would now also say that the rating for craftsmanship is -1, and another -1 for wear, for an overall quality of +0. This would also reveal more about the condition (%) and the standard DD, DR and RE values, (0.25, 25 and 25%) but not the individual values, instead saying what it is "weak" against and "strong" against with no further information. (This specific armour has no weaknesses or strengths.) The final skill check would reveal the exact condition (in HP, out of the maximum) and the exact amount of DD, DR and RE provided against each damage type.

As for your own values, you would know your exact attributes, skills and experience (as well as your ability, competence and experience levels) right off the bat, but wouldn't be able to see derived stats like your DD, DR and RE (and these values for your natural armour, if any) without making a medicine check. More detail would require a higher check.

Of course, all of this varies depending on the exact game. The other two ideas, neither of which is presently being used (but I'm hoping to get team for one, half the reason I'm at the college) are a near future/alternate history FPS/RPG and a space science fiction FPS/RPG/RTS. All the stuff here (except the spell and leather) is from the near-future game's setting, including the "Whiplash" LST and the M3 laser carbine.

Well, I'd love to see it in action and hope you consider the projectiles bouncing off the armor.

It might also be interesting to look at something like sniper elite v2 to see an interesting take on projectile damage.

Well, I'd love to see it in action and hope you consider the projectiles bouncing off the armor.

It's a technical issue. I'll do it if I can. It's not about considering it.

It might also be interesting to look at something like sniper elite v2 to see an interesting take on projectile damage.

I might look, if I have time.