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.
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.
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.
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.
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.