Tuesday, October 09, 2012

Character Fatigue - A preamble

Almost two months ago I wrote this article suggesting to wear characters out instead of making all weapons have equal damage.  I mentioned that characters should wear out during combat to represent their choice of weapon and armor.  This is proposed as an opposing force to weapon/armor min maxing.  After all if you choose a big bad ass battle axe that does terrible damage you're still got to swing it.  Swinging a big axe is more demanding than swinging a sword and more so than slashing with a dagger.  Back then I called for a mechanism that represents character fatigue and gives the little guy an edge with lighter weapons and armor.  This doesn't mean a wizard with a dagger can take down a knight in full armor because he tires slower.  It is more of a counter force to maxing on weapons and armor.  Give a clear benefit to gearing up light.

Since then I've been working on a simple way to represent this.  After all the idea is no good if it is too complicated to implement.  If it takes more math to do this and it extends combat resolution time it will be a no go.

After doing some number crunching and doing some simulations and ideas on how to represent this I've come down with a way to do this in a realistic yet simple manner.  Initially I based the mechanism on keeping tabs on fatigue points and how much an action costs (as you can see here).  Yet that is too complex a mechanism that requires too much math from round to round.  To simplify this I fell back on the idea of aerobic and anaerobic exercise.  I'll go over this so you know what angle I'm coming from.

A human has a max heart rate given by 220 minus age.  So a 30 year old has a max HR (heart rate) of 190 beats per minute.  A forty year old would have 180 beats per minute and so on.  We'll call this max value VO2max (Max volume of oxygen).  Measuring VO2max is a little more complicated and requires equipment to measure.  But for discussion sake we'll take VO2max as max heart beat beyond which the circulatory system can't provide more oxygen to the body and the muscles begin to starve.

Now I'll set different steps leading up to VO2max.  Resting or normal activity is 50% of max heart rate.  Up to 60% is warm up exercise.  Activity producing 70% is fat burning fitness exercise.  Up to 80% is cardio training (aerobic).  Up to 90% is hardcore (anaerobic) exercise and beyond that we approach VO2max and extremely demanding exercise.

A human can perform activities in the resting and warm up area almost indefinitely.   For example walking or marching.  This of course might require certain training to endure the physical demand.  For example blisters, cramps etc in parts that are not used to do such an activity.  Fitness exercise can be done for an hour or so while cardio can be maintained for less.  Hardcore anaerobic exercise can be maintained for a few minutes and much less so exercise leading up to VO2max.

The key is mapping character activities to these ranges.  Movement, encumbrance, attacks, constitution, strength all come into play to define how much a character can do in a single round of combat.  This may seem like a daunting task now, but as we'll see it can be greatly simplified if I take certain considerations.

Think of it this way VO2max is like a jet planes full military power.  Only way to go over that is kicking in the after-burner, but the engine will overheat and drink fuel like crazy.  Below full military power engines will produce a certain amount of thrust based on their design.  At 60% thrust one engine will provide more than another if it's a more powerful one.  In the same way a fit character (read constitution here) will have more output than one with less for the same given heart rate.  So it's not necessary to do complicated math, just figure out the point at which a character reaches each level of exercise.  For example at a jogging speed all characters will have the same heart rate.  Some will be able to carry more or run faster or longer, but the heart rate will be the same.

In next the article I will cover fatigue and movement to explain the basic principles.  Combat related fatigue will be covered in the third article of this series.  Stay tuned.

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