Attrition System Complete (For Now)

Attrition For Overland Travel

This system abstracts the rigors of travel by calculating an attrition value that is applied as hit point damage for characters traveling overland. The primary factor for determining attrition is climate data, namely, temperature, humidity, and wind speed. These numbers are used to derive a hit point value that roughly corresponds to the impact of weather on the human body (heat stress, core body temperature, etc).

Climate Data

Apparent Temperature is a calculated value derived from temperature, humidity, and wind speed that is used to determine attrition. The best way to get good data is to use a historical database of weather (like this one). Use a city that your party is located near and a establish a base date from which to draw the data. For example, if my game session is May 1, 1618, I would map that date to weather data from May 1, 2010. Specifically, you will need the high and the low, average humidity, and average wind speed for the day.

Generating A Value

Use the attached spreadsheet and fill in the values that are shaded light blue. The attrition value in HP is the value highlighted in yellow. Use successive lines from the spreadsheet for successive days since attrition is cumulative.

Using The System During Play

The best way to use this sheet during play is to generate a month's worth of values. Whenever your party travels, delete all the prior days in that month and start counting forward from there. For example, if you populated the entire month of May 2010 as May 1618 and then your party traveled starting May 4th, delete the lines for the 1st through the 3rd.

The Mechanics

Attrition is calculated by using the Apparent Temperature in a correlation between temperature and mortality rate inspired by this reference. Apparent Temperature is a simplified Steadman equation. Two values are calculated, one based on the low temperature for the day and the other for the high temperature. They are then averaged as the day's attrition value.

Limitations And Common Sense

This system is only designed for creating a hit point effect for overland travel. It assumes people and draft animals are taking appropriate precautions against the weather, are fed and drinking, and traveling at a normal pace.

If these assumptions are not true, I don't change these mechanics. Rather, I increase travel time. For example, a heavy rain storm would slow the travel rate down by washing out roads, causing flash flooding, or washing out bridges or fords. So the damage calculation is the same, but the party is exposed to the elements for a longer period for time. If the party were eating only half rations, reduce their rate of travel as they can't keep a good pace up with an empty stomach. If they are under the effects of an Endure Weather spell, feel free to half the damage.

In the end, this calculation provides a realistic damage for travel; it is up to each DM to use common sense in integrating this into your game world. At least you have a strong foundation for adjudication.

The Importance of (Peer) Review

Did you look closely at the previous post's system for attrition? Did you plug in some numbers to test it out? Did you find out where the system works and fails? Did you notice how incomplete it is?

The post only details hot weather effects on attrition, what about cold weather? The heat index is only valid for temperatures above 80F and humidity above 40%, if you try to use the charts' equation for cold weather, you get nonsensical results.

What type of data we we plug in? High temperature, low temperature, average temperature? Desert travel can be brutally hot during the day and freezing cold at night, how does the above system take that into account?

So there's the direction for the next post, finding what the system is incomplete and making it more robust. Always push your design, always test the fringe cases, and always strive to make them better.

Attrition: New Design Ethos, or, Why Your Design Has Been Found Lacking

I've been kicking around the concept of attrition for overland travel for a while now. Let's re-establish the current foundation for this system.

Attrition accumulates per day, according to a base value added to a temperature/humidity factor. The next day, the base value is the previous day's final value, which is then added to the current day's temp/humidity factor. Rinse, repeat. Here's another way of looking at it:

Attrition(0) = Base damage + Climate factor
Attrition(i) = Attrition(i-1) + Climate Factor

Now the whole concept has been simplified to a single factor, that is temperature and humidity. Those two variables, also called the heat index, should cover the vast majority of the effects of weather on the human body. Precipitation will be factored indirectly, namely, heavy rainfall washes out (or covers with snow) paths and roads, which lengthens travel time, allowing for more attrition to take place.

Now here we are at a crossroads, what numbers do we use? D&D was built on pulling numbers out of assholes in order to answer this question. This is where your design fails too, you do not have to guess at any of these numbers at all. Thanks to the information age, you can find peer-reviewed research on pretty much any topic you want. There is no reason to be building systems out of fairy tale numbers of useless heuristics you just made up.

Ok, so where do we find this information? A quick google search lands me at the Center for International Earth Science Information Network, and a handy research article called "Climate Effects On Human Health". Why, there is even a section of predictive equations! Who would have thought of this, there already IS a system for determining how your environment affects you. All we have to do is translate it into hit points and we are off to the races.

So stop pulling numbers out of your ass for your designs and put in the same amount of time into basic research.

Ok ok, back to this system. Let's see what we can use: TMR = cycle + 0.10e[0.2(F[1] - 90)] This looks extremely similar to what I want, a "temperature-specific mortality ratio" expressed as a base value added to a function of temperature. But I want heat index, or a value that combines temperature AND humidity. Thank you NOAA:

http://www.nws.noaa.gov/os/heat/heatindex.shtml

We have all of our pieces now. Stick our predictive equation into a spreadsheet along with inputs for temperature and humidity. Input the above chart into the spreadsheet and perform a look-up to pull a heat index value to stick into the predictive equation. Then, tune the factors around the exponential term in the equation as well as the output so it translates into usable hit point numbers (nothing too small or too big).

Once the sheet is set up, it takes less than 1 minute to generate an attrition value for the day's adventuring or travel. In the end, you have a system that gives you an answer as fast as you can open a spreadsheet and the answer is based on our shared reality and science.

Oh, need to find climate data for input? You have a few resources from which to work.

Why Saving Throws Hurt the Game, Why They Are Needed

The moments that call for a saving throw represent the pinnacle of tension in D&D. They lie at the crossroads of defeat and success, of life and death, and can be the culmination of an evening or a year's campaigning. So why are we rolling a die at this high point? Why are we leaving the resolution of our shared time to random chance, no matter how intelligently or recklessly the game has been played?

The moments that call for a saving throw represent the mundane points of D&D: a pit placed in a hallway, a random trap rolled off some table, or the effects of a harsh environment. Again, random chance takes the place of smart/careless behavior and turns these aspects into something resembling adventuring attrition.

Saving throws are overused. When I first talked about taking attrition damage during overland travel, one commenter wanted to add a save to avoid a day's damage. Like you can really avoid the effects of the environment by being bad-ass? More likely, he was calling for saves because the PCs are precious and should be afforded every opportunity to survive/thrive regardless of smart/reckless play.

Well, the real reason saves are overused is because D&D is under-designed. How many mechanics are just rolled up into a saving throw? Spells, abilities, effects, poison, traps, magic items, the list goes on and on. Just throw a save on an action to create a lazy mechanic to adjudicate its effects. It isn't even a robust and elegant mechanic that could be applied to numerous situations; it is just lazy. Maybe the original designers ran out of creative steam and then we all just kind of turned a blind eye to this gaping hole in the game's mechanics. Or maybe we are blind to the failings of tradition.

Either way, saving throws are a boring, lazy, static mechanic that form an umbrella over countless actions and opportunities in game that could have mechanics designed to add tension, flow, and enjoyment to the game.

Magic In Design

So we have magic in D&D, and we have D&D's implied setting. We have a continuum of responses on how to reconcile magic and how it affects the daily existence of our fantasy constructs:

On one end, magic doesn't alter the fundamental fabric of an implied setting. This could be accomplished in a number of ways, but at its extreme, the affect of magic on the setting is completely ignored on the macro level. Society runs like our anachronistic notions of how medieval life might have been.

One justification here could be that magic has no net affect on the history and development of a setting. For example, Alexander the Great gets a Raise Dead on 323 BC, but a weak later an assassin hits him with a Disintegrate spell, so the whole affair is a wash. Or use any other justification one desires.

The other end of the spectrum, easily enough, is a setting that is devised, designed, and developed with the affect of magic in mind. For example, continual light spells function as medieval gas or electric lights, so work can be performed at night, leading to a more advanced industrial capability, etc etc etc.

Your mileage may vary, feel free to pick any point on that continuum. I hope this is all very obvious.

This campaign leans heavily towards the "no net affect" aspect of magic. I want to play in a pseudo-historical 17th century, so why would I want to drastically alter the social and technological fabric of the world? But I also want to play D&D, so magic is definitely in. So there's your justification for why I hate science. Or magic. I can't even tell at this point.

Magic Users Don't Make For Better Scientists

A comment by Alexis got me thinking. Here's what he said:

But how is it that in a world of magic it isn't obviously possible for a few bright-thinking mages to invent the equivalence of kerosene or sterno?

Magic and magic users don't make for better scientists. Sure, by the rules, magic-users are highly intelligent, so this isn't a knock on character. The main problem with magic is that it doesn't help advance science, so I don't see how it could have a significant, sustained push on science.

Magic doesn't help with discovery. There are no spells that would allow sight deep into the cosmos compared to or better than a telescope to advance astronomy or its application for ocean bound navigation. Conversely, there are no spells for microscopic vision to advance the fields of biology or medicine. There are no spells to isolate, refine, or process elements and compounds to advance materials science. And so on and so forth.

Magic doesn't help with measurement; scientific inquiry is built on measurement.

Magic doesn't help much with generating, controlling, and applying energy. I'm thinking in the form of engines here. Well, maybe the use of a Permanency and some sort of fire spell could create a fuel-less flame. But magic wouldn't help with the invention of gears, cams, and other power transmission systems to deliver work from the heat generated.

You could look at it the other way too. How would magic have helped classical man devise a method for creating concrete? How would it have helped to create new steel and metal alloys (beyond creating higher temperature forges)?

Magic in D&D is geared towards combat, exploration, and all the fun things that go with the game. It could have just as easily been geared towards science (but what kind of game would that be?). It is not like what I am saying here is any big revelation, but it is both a common sense and convoluted answer to how we can have magic and Medieval/Renaissance technology side by side.

Note that I am making a slight distinction between technology and science. An enterprising magic user can use magic to create some wondrous things, but their magic is not advancing (or creating) science or the scientific method.

Again, I'm not saying that an inventive use of magic couldn't create effects that resemble technological advances, but said effects are not advancing science qua science.

Greek Fire

Pursuant to the comment section of the lamp oil post, I looked into Greek fire. Admittedly, I only did some cursory Google and Wikipedia research, so this is not definitive. However, it helps to illustrate a point.

Here's a diagram of a theoretical Greek Fire launcher fitted onto a Byzantize Dromon:

Wikipedia.org

Notice two important aspects of this diagram, pressure and temperature. Even Greek fire had to be heated before it was combustible. Again, like oil, it is not a weapon at room temperature and it would not ignite from a spark or existing flame. In order to employ this weapon, it had to be heated and in order to fire it had to be pressurized.

This is the key point I want to make for flame weapons: they require processing and work (in a thermodynamic/mechanical sense) before they can be employed. So anyone who wants to use incendiary weapons in this world (or any world in which you want to pay attention to such things), is going to have to set up a system more elaborate than a wick and bottle. And even heated oil/Greek fire/etc is not going to be easy to handle and use safely, thus the pressurized launcher. If the history of the boiler and steam engine is any indication, I am sure many a Dromon exploded of its own accord.

Lamp Oil Doesn't Burn

Pure fantasy: blazing walls of lit oil, bombs fashioned from bottles of oil with a lit wick, tossing oil on an enemy and setting them on fire.

None of this is even close to realistic. Lamp oil is made from vegetable oil or maybe fish oil. These oils have a flash point in the range of a two to three hundred degrees. What does this mean to the non-engineer? OIL DOESN'T BURN.

Flash point is a property of liquids; it is the temperature at which the vapors from a liquid will burn when in contact with an ignition source. When oil is underneath this temperature, it cannot be ignited. So all of these oil bombs and puddles of oil suddenly turning into a raging conflagration are all wrong.

Quick science experiment for people who do not believe me: Grab some vegetable oil from your pantry and pour it into a dish. Light a match and hold it above the oil. Does the oil burn?

No, seriously, go and do this then come back if you don't believe me. I'll wait.

Oil does burn, that is why lamps were fueled by oil. However, the oil has to be heated first before it will ignite. How do we accomplish this? With a lit wick. The wick heats the nearby oil above the flash point causing the oil to give off enough vapors to sustain a flame. That's why you start an oil lamp (or candle, same principle) by lighting the wick for a few seconds with an external fire source before the flame will catch.

[On the other hand, modern petroleum products ignite easily. The flash point of gasoline is around -44 degrees. Kids: don't play with gasoline.]

If you just had a bottle of oil and poured it on the ground, you are never going to get it to ignite with a torch. If you stick a wick into a bottle of oil and light it, the wick will burn. But if you throw that bottle and it shatters, the oil will not ignite and the flame will be snuffed out. Remember, only a tiny portion of the oil very close to the wick is hot enough to burn.

Ok, so that is a mild pet peeve off my chest. If you are bothered by basic physics, don't let your players and monsters toss around molotov cocktails made from vegetable oil. I don't.

Discussing Cavalry Charges

With the rules for cavalry charges in place, let's discuss its impact.

Charges are definitely a climactic action with this mechanic. The attackers are risking losing their mounts and suffering 1 or 2 unopposed attacks against themselves. However, they can totally break an opponent's position, and if able to pursue, rain down a number of unopposed attacks themselves.

While it seems like charges could make combat trivial to the point of first charge wins, take a look at monster Morale values. It seems like many rolls would come down to both sides succeeding, so it would only be applied in cases where the chances for success can be tilted towards one's favor. Typical values for humanoids range from 7-9, meaning that a failed rolled is not going to be common. Even so, on most bad rolls, the defenders won't be failing by a wide margin. There are a large number of monsters who have 12 morale since they are undead or otherwise non-living. Plus, a defensive line equipped with Pikes will have a morale in the range of 9-11, making them rather safe from cavalry charges.

On the other hand, this option can offer some variety in fights and turn typical encounters on their head. Mass amounts of low HD monsters (or hirelings!) are particularly susceptible to a well timed charge. Morale affects have a much more profound affect; a bless or curse spell could really change the tide of an encounter. Controlling the field of battle also plays an important role; if one side can't defend against a charge then they need to pick broken terrain that won't allow a charge to occur.

I'd love to actually see this put into play during a game session to really push the system. Ultimately, it is only a roll of a few D6s so the true test of the mechanic would be its application during normal adventuring. How often would players use this type of tactic? How often should a DM throw in some goblins on worgs who are willing to charge their enemies? Orcs on horseback? Would horses and mounts actually be worth their corresponding real world value in D&D beyond a convenient method of travel and hauling loot? Could you work in a gigantic mount, like an elephant or something even bigger, and really go on a tear?

One day, I'll get to put this rule into a game and see how often it comes up...

Adjudicating Combat Maneuvers

Design Goal: Create a unified foundation and common basis on which to adjudicate special combat maneuvers.

Pike and Cavalry in D&D Combat

Delta has a good post on a "Close Combat Trinity," explaining the relationship between swordsman, cavalry, and pikemen as "Historically: Swords best Pikes best Cavalry best Swords." In applying this to D&D, he notes that swordsman are well represented by typical D&D combat, but pikemen and cavalry are not. In particular, he notes "cavalry attack is intrinsic to the unit's own movement" and "pike attack is intrinsic to the unit's enemy's movement." This is not modeled in D&D combat where movement and attacks are modeled as distinct actions or fall into abstraction if you go by the 60 second combat round. Yet, this is a great disservice to the actual mechanics behind these two weapons and how they influenced warfare.

You Can't Go Home Again, or, Designing For Players

I spent the last two weeks visiting family and friends up north and it got me thinking about designing explicitly for an expected or actual player(s). Should a DM design world and rule settings that cater to a specific play style or type of player?