OT: Making a Game System (part 2)

[Omnirizon]

part 1 was the 'Western v. Eastern' marital arts thread



so I'm crafting a model for combat now. take a look at what I've got so far and see what you think. feedback is appreciated. keep in mind this is for a computer game, so typically time consuming formulas are no problem...

for starters, characters possess two "life" measurements rather than just one. The first is 'vitality', and then there is the typical 'hit points'. Vitality is actually more of a fusion of traditional hit points and fatigue, whereas 'hit points' in my system are the representation of physical body integrity (like not having holes and cuts on your body and stuff).

the reason for this seperation is that vitality can represent the energy, skill, and spirit a character brings to defending and attacking in a fight. it makes sense that this should increase drastically with character advancement. physical body integrity should not increase much and should be subject to sudden trauma when subject to stress that vitality couldn't defend against.


that sounds nice and all, so now how to model it?

to keep things simple, lets consider two combatants in a controlled situation; say a duel. more complexity (for multiple combatants) can be added later.


for simply 'meleeing' there is a vitality cost each round (or loop). this cost is modeled using an asymptotic curve:

1. vitalitycost = 1 / h

'h' will be a harmonic mean derived from many things including physical stats, skills, and equipment; equipment will typically lower the harmonic mean, while the other inputs will work to raise it, but this is not always true. A harmonic mean tends to cluster around the smallest numbers, creating a heavy reverse salience influence, preventing players from compensating for a heavy drawback by simply dumping a lot of 'points' (or whatever) into another relevant skill. This will also make heavy armor and equipment hard to compensate for since they are the biggest drag on 'h'.

harmonic mean, for those interested in knowing more

so that is the vitality cost incurred each round of fighting.

next, each combatant makes a 'threat roll' and a 'defense roll'. the threat roll is

2. threat = h + r

'h' is the harmonic average of relevant factors (think str, dexterity, equipment) while 'r' is a random number (most likely an open ended dice roll)

the defense roll is

3. defense = 1 / (h + r)

this is just like the vitality cost, but 'h' will likely be derived from different factors, and there is an added random element.

next, threat is multiplied by defense. since defense is asymptotic it will lower threat as it increases, but never eliminate it.


so a quick recap in the form of a pseudo-formula

vitcost + (threat * def) = vitdam

note that vitcost and def are intrinsic to the character, the threat is the external threat; remember def is always between 1 and 0, and approaches zero. vitcost is flat amount where less is better, and threat has normal distribution that approaches infinity. in some ways the threat and defense are like the 'attack' and 'defense' of dominions, but they are interacted (multiplied) rather than just compared to see if damage occurs. I thought this better modeled the kind of fuzzy mish-mash of factors occuring during battle, both blunting extreme advantage while also lowering extremely lucky to the point of implausibility. In an RPG this would be preferred. Also, increasing vitality with character advancement is satisfying, while remaining more realistic than increasing hit points.


if a large amount of vitdam is suffered in a single round, there is a chance the character will suffer physical damage. this is to represent the glancing blows and nicks two combatants will incur as they spar.

phydam_chance = phydam_chance(vitdam)

here there will be some formula, dependent on vitdam, that determines the percentage chance of suffering physical damage. larger amounts of vitdam make it more likely. this could perhaps use vitdam as a ratio of total vitality; similar to affliction chance in dominions.


once vitality is eliminated, physical damage can occur. however, there is also another layer of 'armor' which has not yet been modeled. before I do that, consider some implications of my 'vitality-threat' model

1. in melee fighting, strength, dexterity, and arms can reduce the threat to vitality suffered each round, as well as increase the amount of threat you can present; this sounds reasonable.

2. armor can actually increase the vitality damage suffered each round since it will have a negative influence on the defense roll, however it may end up preventing physical damage. does this sound reasonable? vitality is sort of a buffer from actual damage that the character is able to present due to skill, energy, and spirit. having lots of armor on would translate to vitality being depleted quicker (and not just because of vitcost, but due to the defense penalty of armor), and allowing threat to become physical damage quicker. however the armor would then begin providing a barrier to physical damage.

3. imagine vitality-threat in the case of, say, a rocket propelled grenade. does it still make sense? defense would reduce threat damage multiplicatively. this sounds plausible in a sword fight, but how can your defense reduce a traumatic explosion of a grenade to, say, a tenth of its full power? well, i suppose _getting out of the way_ would help. therefore, having armor on and actually suffering vitality depletion because of it makes sense here.



so does this whole threat-vitality-physical damage model make sense? I like it a lot better than simple 'health' or 'hit points', and I like fusing fatigue into it since when you get fatigued you will not have as much vitality to defend with, and it allows fatigue to be represented as the lack of vitality, rather than the accrual of fatigue; its also more satisfying, and more accurate, to increase the amount of vitality with character advancement, and thus the amount of exertion and stress that can be suffered before becoming fatigued. This does not seem to allow for dominions usage of fatigue to lower attack and defense (or threat and defense); however that could be incorporated by adding modifiers based on the ratio of current vitality to maximum vitality. This model also allows for the more accurate modeling of, say, two unarmored fighters sparing; or of a combatant dodging an explosive device. I am not wanting to directly compare Dominions to my own combat system, because they are meant for two different things. However, my system is actually very heavily Dominions influenced, but modified to be able to represent RPG style personal combat in a way that would be more satisfying when playing an RPG.



thoughts or suggestions?
also, any input on how to determine or weight the inputs into the harmonic averages? most likely relevant stats will be strength, dexterity, psyche, perception, and arms and skills modifiers.

below is a full stats list, I havn't really done much work on these actual effects, or any work on the effects of weapons and armor.

Cognition:		Represents analytical and synthetical capability
Perception:		Represents percpetion of the physical world; both eyesight and powers of observation
Psyche:			Represents mental stability and strength

Strength:		Represents physical strength
Dexterity:		Represents physical nimbleness and grace
Memory:			Represents rote storage and recollection of objects and procedures

Constitution:	        Represents the resistance to physical destruction
Spirit:			Represents spiritual strength and presence
Charisma:		Represents personal magnetism and influence