Zero Sum Rule (Shadwolf)

There are several different genres of game today (sadly less than there use to be).  Each of them has its own peculularities, but all seem to have the consistent problem that imbalance develop in nearly every game designed.  Observation of these games has lead me to the conclusion that there are certain similarites in many of these games.  For these purposes, I will be dealing with any game that deals with combat.  This includes pen and paper RPGs, CRPGs, RTSs, FPSs, MMORPGs, turn based strategy games and a variety of others.

There are a few basic considerations for combat: how fast is the unit, how much damage does the unit do, how fast does it do damage, how hard is it to hurt, and how much damage can it take before it is disabled (not neccessarily killed).  In an RPG or FPS, the unit is the player character or their opponents; in a strategy game this refers to the combat units of all sides.

The first of these considerations, and possibly the most important, is how much damge the unit does.  This is closely linked with how fast the unit does damage.  The hardest part of solving this is picking a useful unit of time.  This unit should be based on how long it will take to kill another unit.  This unit of time can then be compared to the damage of a given attack to generate a damage over time ratio.  This should include the healing rate of the average unit.  If you do 5 points of damage in a given time, but the target heals 2, you only actaully did 3.  This damage should be expressed in terms of a percentage of the average health a unit has.  Thus, you should end up with something like a 5% per second or a 7% per round ratio.  A maximum and minimum value has to be set for this.  Many a game has been broken for lack of this.  Most games start with a maximum, but each new episode or suppliment wants to add a weapon or attack that is more powerful than anything that’s been done before.  The values keep climbing and the game gets broken.  You need to ensure that this maximum is never exceeded, now matter how cool or unique the circumstances.  A good guideline is around the maximum health possible for any unit.  The minimum is a little harder to judge, but it should be at least higher than the minimum rate at which a unit can heal.

Once damage over time has been determined, a value should be assigned.  Remember that higher damage attacks have a better chance of killing the enemy in one shot and so should have proportionally higher values.  An example might be as follows:


Next, how hard is this unit to hurt compared to other units?  This would then be expressed in terms of what percentage of damage it typically avoids.  This would then allow you to determine how many shots an average attack will take to disable the unit.  This number would then correspond to a value much as damage over time did.  This value would be added to the damage over time value.

The last positive value to add would concern how fast the unit is.  The value for this would depend on not only the speed, but whether or not there are ranged attacks and how this speed affects the use of thos attacks.  If the speed is high enough to constantly stay at range and avoid melee units, or to close with any ranged unit before it can fire, then this value should be inordinately high.  If it is fast enough to allow one melee unit to eventually close with another, it should be moderately high.  Again, this value is added to your total.

As a blance to all these values, cost must be determined.  Cost may have up to three factors, intitial cost, upkeep cost, and time to produce.  Intiatial cost should be the least of these.  The three should balance out to give a negative cost which reflects the potential usefullness of the attack or unit.  This cost, when added to the above values, should give you a zero sum.  The net effect is that all attacks, if you’ve done it right, should be balanced.

How this works:

For an RTS you might have infantry that would be slow, weak, but cheap.  Cavalry might be much faster and have a stronger attack, but be weak on hit points and cost more.  A dragon might be stronger, faster and harder to kill, but the cost and upkeep would be outrageous.

For a pen and paper RPG, a CRPG or an MMORPG a fighter might have a good fast attack with his sword that does moderate damge and costs him one stamina per round to use while a mage might have a fireball that does huge area effect damage at range, but takes 3 turns to fire and costs 10 mana to cast.

These values work best if stats are kept as low as possible.  If the weakest character has 3 health and the strongest has 10 and most attacks do 2 to 4 damage, there is a good spread and all characters will be fun to play.  If the weakest player has 10 health and the strongest has 250 and attacks do anywhere from 10 to 100 points a shot then any character with low hitpoints will be perpetually one-shotted whereas the high hit point players/units/monsters will completely invalidate the use of any but the most numbercrunched weapons.

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