High and Low Gravity [long]

[Cheiromancer]

I've done some some thinking about the rules for high and low gravity settings. Without going into the details (which are quite long- if there is any interest I'll post them), here are my conclusions:

The basic increment for gravity is 7.1%. If gravity increases by a factor of 1.071 you experience the following:

A -1 effective penalty to the appropriate ability score when determining encumberance (Str), whether one is fatigued or exhausted (Con) or ability checks such as for Balance (Dex), Tumble (Dex) or Climb (Str).

A decrease equal to 1 / 1.071 in base speed (round to convenient values) and distance jumped, and in the range increments for missile weapons.

To stack increments, multiply or divide by 1.071. Many of the numbers will be ugly, but not all:

four increments: -4 penalty to designated ability scores; base movement rate, jumping distance and range increments diminished to 3/4 standard.

six increments: -6 penalty, movement etc. reduced to 2/3.

seven increments: -7 penalty, distances reduced to 60% standard (grid marks can stand for 6 feet instead of 10 feet).

10 increments: -10 penalty, distances reduced to 50%.

16 increments: -16 penalty, distances reduced to 1/3.

If someone's effective ability score reaches 0, they are incapacitated in some way; they cannot get up, they are permanently exhausted, their heart gives out or limbs break, etc..

Falling damage: the distance increment for falling damage is also reduced in a high gravity zone, and increased in a low gravity zone. If you are in a +7 gravity, damage is 1d6 per six feet. I think the maximum damage should still be at 20d6, though. So at a -6 gravity the damage would be 1d6 per 15 feet, also capped at 20d6.

Incidentally, I've decided that a standard DnD setting probably has a lower gravity than we experience. That is why there are so many large creatures that don't collapse under their own weight, and why so many creatures can fly despite having wings that are too small for their size. Well, it helps explain it; dragons still need magic to exist. Our own world is about a +6 gravity world if a DnD setting is +0.

In comparison, Mars is a -8 world and the moon is -20 (DnD being +0). I have a couple of ideas to determine whether a given creature can cope with being in a high gravity environment, what effect acclimation has, and so on. But lets see if anyone reads this, first.

 

[thesilentbard]

why make it complicated?

I suggest you round the 1.071 factor to 1 and the 7.1% to 10%.
I'm not sure DMs will be wanting such accurate details.


What do you dislike with the normal rules?

What's the 7.1% increment and 1.071 factor anyway? Could you please describe it a bit more? I think I understood, but I'm not sure, it's a bit vague the way it's described.

 

[Cheiromancer]

I began with geometry. If you have two cubes of equal density, one twice the size of the other, each supported by a horizontal surface, the larger exerts twice the weight per unit area on the supporting surface than the smaller one does (each supporting face has two cubes on top of it, not just one). As far as the smaller object is concerned, doubling its size is much like doubling the gravity it experiences. Similarly, tripling an object’s size is like tripling the gravity it experiences, and so on.

A Large or Medium-size creature who doubles in size increases its weight eightfold, and it’s size category increases by one (MM 5). Its carrying capacity is automatically doubled (PH 142 “Bigger and Smaller Creatures”) and its Strength increases by 8 points (MM 12). 8 points of strength triples its carrying capacity (PH 142, Table 9-1; e.g. from Str 15 to 23, or from Str 20 to 28). With a doubling of carrying capacity due to size, the net increase in carrying capacity is six fold.

Note that the Strength increase is a trifle anomalous; if a creature’s weight increases eightfold, its carrying capacity should increase proportionately. A Strength increase of +10 would make more sense, since that quadruples the carrying capacity.

The table would make more sense if a tripling of the creature’s size resulted in two size increases, since two size increases corresponds to a +16 to strength, or (from PH 142, Table 9-1) a ninefold increase in carrying capacity. If the “Bigger and Smaller Creatures” rule of PH 142 is generalized, tripling a creature’s size should automatically triple its carrying capacity. Thus a creature three times as big should carry 27 times as much. Since it also weighs 27 times as much, this is exactly as it should be.

Now remember the cube? A creature who triples in size is like a creature who experiences three times normal gravity. But a creature who triples in size must increase its strength by 16 points in order for everything to scale properly. So if 16 points of strength exactly balances a tripling in gravity, what increase of gravity balances an increase of one point of strength? Since 1.0711 is the 16th root of 3, it must be a 7.11% increase.

If doubling in size increased Strength by +10 (which it probably should), a +1 to Strength would correspond to an increase of 7.18% (1.0718 is the 10th root of 2). So either way a 7% increase in gravity needs to result in a +1 increase of Strength for the situation to remain the same.

Another way of looking at it is to say that if gravity increases by 7%, the creature’s strength effectively decreases by 1. This would be for purposes of determining encumberance and strength based checks (climb, balance, jump and tumble at least, things like Ride and Swim involve other considerations).

The relationship between encumberance and strength is a problem. Specifically, the weight of the creature doesn't figure into its own encumberance. But it should; old or overweight people often do not have sufficient strength to move their own bodies around efficiently, and so they move slowly, can't run very well, and tire more quickly. Even if they are not carrying anything, they are moderately or heavily encumbered.

Even if you were in the best of shape, suddenly adding 40% to your weight would be an encumberance. Suppose you weighed 175 lbs; your weight will suddenly increase by 70 lbs. Now, this is weight and not mass; you start, stop and turn corners as if you were your old weight, but you need more energy to remain standing.

The best way to conserve energy while moving would be to move more slowly; the way the encumberance chart shows this is by making your speed go down.

Another way of looking at the problem was to consider encumbrance. After all, if you weigh 175 pounds and the gravity suddenly doubles, you are now carrying around an extra 175 pounds. Well, not quite. Your mass hasn’t changed, so the inertia you feel when you try to turn a corner or come to a stop- that won’t change. In fact you may find it easier to turn a corner, since your increased weight means better traction between your feet and the ground; you are less likely to slip. But when you are standing still, it will feel like you have an extra 175 pounds on your shoulders.

I decided to handle this with a combination of strength reduction (for the purpose of determining encumberance) and reduction in base movement rates. This worked out quite nicely for the damage caused by falling, since if it is linear to distance it is probably linear in acceleration as well. And 2ad=v^2, so this has to do with the kinetic energy (1/2 m v^2) that a person has when they hit the ground.

I wouldn't expect DM's to use the 7.1% (adding 7.1% is the same as multiplying by 1.071); they would probably use "nice" increments as given above. 4 or 6 or 10 or something.

 

[ax0n]

Hi Cheiromancer,

Thanks for the input. We could certainly use your essay on gravity for the Netbook of Planes. Unfortunately, there is some small amount of legal stuff before we can use it, namely you have to do the following:

1) Sign the Permission Agreeement which makes sure you understand what it means when you open your work for us to use. More details can be found on the FANcc web site .

2) When you have completed and sent off your PA you should receive a contributor ID. You can then send your work along with a Statement of Authority to contribute and we can use it.

Sorry it's so lengthy, but hopefully we'll be streamlining the process pretty soon. We'd really like to use your work, and I think its worth the effort to see your name in print

 

[Cheiromancer]

I've filled out and scanned the Permission agreement. Where can I e-mail it to? (dndcommunitycouncil.org was not found by my mail server).

Regards,

 

[ax0n]

I asked the Council and they gave me an alternative address to send PAs:

creatures@cooleys.org

BTW, what did you think of the rest of the rules for Plane Descriptions?

 

[Cheiromancer]

I would probably do the high and low magic fields in a different way. The rest is good, and it suggests all kinds of special descriptors that can be applied to planes.

One thing I don't understand is the way that collaboration in this netbook is supposed to work. Wouldn't it be better if people posted their ideas in a forum, so that they could build off of and improve what everyone is thinking? These silent forums are kind of spooky.

And I see a distinct overlap with the world-building section of the Cosmonomicon. heck, "World" is even a category used in the plane descriptions document. There would be some interesting cross fertilization there, too.

Regards

 

[ax0n]

One thing I don't understand is the way that collaboration in this netbook is supposed to work. Wouldn't it be better if people posted their ideas in a forum, so that they could build off of and improve what everyone is thinking? These silent forums are kind of spooky.

At the moment most of the collaboration is going on at the Netbook of Planes mailing list. When the netbook first got started we weren't at EN World and didn't have these lovely forums. To be honest, I find the forums slighly quirky which is why we've stuck with the mailing lists and we use the forums for public announcements and interraction. If you want to get more involved (and we'd love to have someone like you get involved in our team) think about signing upto the mailing list. You don't have to receive emails to read postings so, please, think about it. I'm sure we can get you a position on the team as well if you feel like getting more involved.

BTW I have been involved with the Cosmonomicon but, until they get off the ground again and the 1st Edition of the NboPl is under our belts, there won't be much happening on that front.

 

[Cheiromancer]

Simplified high gravity rules

Just a draft...

High Gravity: Creatures in a high gravity field find it more difficult to move, and get tired more quickly. Less sturdy creatures may be incapacitated, and may even die.

High Gravity areas typically range from +1 to +10. For each "plus", do the following:

• Reduce effective Strength and Constitution by 1 when determining encumberance and fatigue/exhaustion
• add a -1 circumstance penalty to all movement based checks (Climb, Balance, Tumble, etc)
• add +1 hp per die to all falling damage
• reduce the range of all missile weapons by 5%

If someone's effective ability score reaches 0, they are incapacitated in some way; they cannot get up, they are permanently exhausted, their heart gives out or limbs break, etc..

Creatures of size large or greater receive double the indicated penalties, while creatures of size tiny or smaller halve the penalties.

 

[thesilentbard]

Wow! Respects to your hard thinking!

But I don't quite understand this:

As far as the smaller object is concerned, doubling its size is much like doubling the gravity it experiences. Similarly, tripling an object’s size is like tripling the gravity it experiences, and so on.

I thought everything on our world experienced the same gravity from our planet. Did I misunderstand some part of your reasoning?