Population Density in Traveller

Poking through Classic Traveller Book 3, I found a section that has always kind of bothered me.  In discussing world generation, under population density it says "For comparison, the following population densities are common on twentieth century Earth.  Earth on the whole has a population of about three billion (population level 9), this is approximately 5 persons per square mile, or 16 persons per square mile of land area.  Europe is populated at about 151 person per square mile, the equivalent of population level 10.  The Netherlands contain 1500 persons per square mile, or about population level 11.  Hong Kong has 10,000 persons per square mile, the equivalent of population level 12."

Now, there are several reasons this bothers me.  First, imperial measurements don't really fit well with science fiction, in my opinion, unless we're talking about Victorian sci-fi, or Flash Gordon/Buck Rogers style pulp sci-fi.  All these measurements should be in metrics.  Second, population is determined by 2D-2, with no DMs, so there is no level 11 or 12.  But perhaps most importantly, the population score is represented elsewhere in Book 3, as well as later in Book 6, as a general population value and not a population density.  Therefore, a small planet would have a higher population density than a larger one with the same population score.  Furthermore, since people live primarily on land, planets with larger oceans will have higher population densities than desert planets, houseboats, platforms, and underwater domes notwithstanding.

So, in a fit of gamer ADD, I needed to do some fiddling around in general terms.  Nothing I've done here is really ground-breaking, but this kind of thing should be taken into account by Traveller GMs, or GMs of similar games like Stars Without Number.

First and foremost, on any planet where humans can't just hang out on the surface in street clothes, none of this applies.  If there's no atmosphere, not enough atmo, or a toxic atmo, all settlements will be built like space stations, with airlocks and air processing and not a whole lot of privacy.  In these situations, the economics of building safe habitations and providing appropriate life support will ensure relatively high population densities in settled areas, and wilderness everywhere else.  Similarly, on planets with 100% of the surface covered by water, settlements will be artificial structures, and economics will tend to ensure high population density (although if a water world has a nitrogen/oxygen atmosphere, a lot of people might opt to buy their own watercraft to live on and get away from the crush).  Those planets with breathable atmospheres have more options, though...high density city living, or a lonely cabin out in the sticks.

What I've done here is calculated out the approximate land area of different sized planets with different hydrographics ratings.  Since this is just a thumbnail sketch rather than a comprehensive rule system, I just went with default planet sizes (no variations from the standard) and default hydro ratings (ten percent increments).  I also did these calculations in square kilometers (!)

	hydrographic rating
world size	0	1	2	3	4	5	6	7	8	9
S	306K	na	na	na	na	na	na	na	na	na
1	7.65M	na	na	na	na	na	na	na	na	na
2	32.13M	28.92M	25.7M	22.49M	19.28M	16.07M	12.85M	9.64M	na	na
3	71.91M	64.72M	57.53M	50.34M	43.15M	35.96M	28.76M	21.57M	14.38M	na
4	127.5M	114.75M	102M	89.25M	76.5M	63.75M	51M	38.25M	25.5M	12.75M
5	199.41M	179.47M	159.53M	139.59M	119.65M	99.71M	79.76M	59.82M	39.88M	19.94M
6	287.13M	258.42M	229.7M	200.99M	172.28M	143.57M	114.85M	86.14M	57.43M	28.71M
7	390.66M	351.59M	312.53M	273.46M	234.4M	195.33M	156.26M	117.2M	78.13M	39.07M
8	510M	459M	408M	357M	306M	255M	204M	153M	102M	51M
9	645.66M	581.09M	516.53M	451.96M	387.4M	322.83M	258.26M	193.7M	129.13M	64.57M
A	797.13M	717.42M	637.7M	557.99M	478.28M	398.57M	318.85M	239.14M	159.42M	79.71M

This next table is barely of interest.  Just a rough estimate of people per square kilometer, based on population rating and a few benchmark planetary land areas.  Because population rating is just an estimate in the first place, I didn't bother getting into a whole lot of detail, and anyone who can divide by ten can easily recreate the table.  I also didn't bother working out numbers for less than 1 per sq km...it's basically all wilderness at that point.

	population rating
surface area	0	1	2	3	4	5	6	7	8	9	A
100K	0	0	0	0	0	1	10	100	1000	10K	100K
1M	0	0	0	0	0	0	1	10	100	1000	10K
10M	0	0	0	0	0	0	0	1	10	100	1000
100M	0	0	0	0	0	0	0	0	1	10	100
1G	0	0	0	0	0	0	0	0	0	1	10

So, finally, I looked up some representative countries with these approximate population densities.  At 0 (less than 1 really) we have Greenland...essentially small settlements in the most appropriate areas (most efficient resource exploitation, most comfortable weather, most scenic areas; you have a whole planet to pick from, so why not?) with the rest of the planet as uninhabited (possibly uninhabitable) wilderness.

At about 1 per square kilometer, there's Mongolia, with some decent sized cities and widespread, low-level habitation everywhere else (basically wilderness).

At about 10 per sq km is Russia; large cities and industrialized areas but still large unexploited wilderness areas.

At about 100 is Turkey (and most industrialized modern countries for that matter).  Cities, some sprawl, but still a lot of wild areas and low density agricultural areas as well.

At about 1000 people per square kilometer, we have Bangladesh.  Densely populated cities with some very tall buildings, cities and towns tend to blend seamlessly into each other, but there are still some rural areas punctuated by smaller cities and towns.  The Hawaiian island of Oahu has about this same level of density, if you've ever been there.

At about 10,000 people, our example is Singapore.  Once you start getting up this high, rural areas really get crowded out.  Lower levels of overall density have pockets of highly dense settlement, but it's getting pretty uncomfortable now; people spread out as much as possible.

The smallest planets with the highest populations can reach up to 100,000 people per square kilometer.  There are some places on Earth now with that level of population density, but they're not well known...basically some neighborhoods in some already densely populated cities.  I can only imagine a planet-wide version of this would be the Traveller equivalent of Coruscant, with city everywhere, and the only variation being how tall the buildings are.

And now that itch of mine is scratched.  More accurate population densities in Traveller's world generation.  I've been thinking about working up some system using Zipf's Law to figure out more detailed settlement patterns for science fiction games.  Whether I come up with anything worthwhile remains to be seen.  And of course, I can't seem to stay on task for almost anything anyway.  Today's post came about when I intended to work on another Patron for DCC.  We'll see what happens I guess.

DCC Patron: The Drownded Man

So here's that Patron I've been working on seemingly forever.  There's a part of me that feels on some level that there should be a more balanced system for making Patrons, but I guess I'll get over it.  Anyway, this guy comes from a frontier fantasy setting I put together for Hero System a few years ago, set in a faux North America, with pirates and vikings on the coasts and eagle-eyed woodsmen up in the hills, with some Salem style witchery scattered around.  The Drownded Man in that document had just a couple of sentences dedicated to him (he was really just a skin for a devil template), but he seemed flavorful enough to stretch out into a full fledged Patron, especially for a Shudder Mountains game.  Yeah, I stole a lot from Wellman in that setting too.  Here's hoping Blogger doesn't ass up my OpenOffice file too bad...

The Drownded Man, as he is called even by those who should realize the grammar is wrong, appears as his name suggests. He is bluish and sopping wet, and his eyes are clouded and roll about unfocused. He holds the secrets of sunken things, and will share with those willing to trade. What he really wants is company.

Invoke Patron check results:

12-13	The Drownded Man glances the caster's way. The air becomes dense, slightly impeding movement and breathing. The caster suffers a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. The nearest enemy (within 20') suffers double these penalties. Any allies of the caster between the two are affected the same as the caster. These effects last 1d4 rounds.
14-17	The Drownded Man briefly turns his attention to the caster. The air becomes dense, slightly impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. The caster and all allies within 20' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 20' suffer double these penalties. These effects last 1d4 rounds.
18-19	The Drownded Man rests his gaze on the caster. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. The caster and all allies within 20' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 20' suffer triple these penalties. These effects last 1d6 rounds.
20-23	The Drownded Man sends some minions to feed. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. Shadowy fish-shapes swim through the air and nip at anyone in the affected area. The caster and all allies within 20' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 20' suffer triple these penalties. In addition, the caster and all affected allies take 1 damage per round; affected enemies take 1d3 damage per round. These effects last 1d8 rounds.
24-27	The Drownded Man sends many minions to feed. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. Shadowy fish-shapes swim through the air and nip at anyone in the affected area. The caster and all allies within 20' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 20' suffer triple these penalties. In addition, the caster and all affected allies take 1 damage per round; affected enemies take 1d6 damage per round. These effects last 2d6 rounds.
28-29	The Drownded Man sends a bloated corpse to aid the caster. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. Shadowy fish-shapes swim through the air and nip at anyone in the affected area. The caster and all allies within 30' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 30' suffer triple these penalties. In addition, the caster and all affected allies take 1 damage per round; affected enemies take 1d6 damage per round. These effects last 2d6 rounds. Lastly, a bloated corpse swims into existence at the edge of the area of effect from the extraplanar realm of the Drownded Man. It fights and otherwise aids the caster for 2d6 turns. Bloated Corpse: Atk +4 (dmg d4+1/d4+1 punch); AC 12; HD 4d12; MV 20'; Act 2d20; SP sopping wet and immune to fire damage, grab if both fists hit; SV Fort +3 Ref +0 Will +3; AL C. Bloated Corpse demons of the Drownded Man appear to be undead and can be turned as such. They are fat with decomposition, crawling with crayfish and mayfly larvae, and saturated with foul water. If summoned to fight, they will attempt to grapple enemies (requires a successful hit with both fist attacks) and pull them into the area of drowning created by the Invoke Patron spell if they're not already there.
30-31	The Drownded Man sends a bog mummy to aid the caster. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. Shadowy fish-shapes swim through the air and nip at anyone in the affected area. The caster and all allies within 30' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 30' suffer triple these penalties. In addition, the caster and all affected allies take 1 damage per round; affected enemies take 1d6 damage per round. These effects last 2d6 rounds. Lastly, a bog mummy swims into existence at the edge of the area of effect from the extraplanar realm of the Drownded Man. It fights and otherwise aids the caster for 2d6 turns. Bog Mummy: Atk +8 (dmg d8/d8 punch); AC 15; HD 8d12; MV 30'; Act 2d20; SP sopping wet/immune to fire damage, boneless/immune to blunt trauma, grab if both fists hit; SV Fort +4 Ref +2 Will +4; AL C. Bog Mummy demons of the Drownded Man appear to be undead and can be turned as such. They have blackened skins, bright red hair, and a disquieting bonelessness to their movements. Like Bloated Corpses, they will grab enemies outside of the area of drowning and pull them in.
32+	An avatar of the Drownded Man appears. The air becomes dense, impeding movement and breathing. Clothing, hair, and similar items will swirl around as though underwater. Debris kicked up on the battlefield will also swirl around and take time to settle; this can make seeing extremely difficult. Shadowy fish-shapes swim through the air and nip at anyone in the affected area. The caster and all allies within 30' suffer a -1 penalty to saving throws and AC, as well as any attacks depending on swinging momentum (most bashing and cutting attacks). Stabbing and biting are not affected; other attacks are left to the GM's discretion. Enemies within 30' suffer triple these penalties. In addition, the caster and all affected allies take 1 damage per round; affected enemies take 1d6 damage per round. These effects last 2d6 rounds. Lastly, an avatar of the Drownded Man swims into existence at the edge of the area of effect from the extraplanar realm of the Drownded Man. It fights and otherwise aids the caster for 2d6 turns. Drownded Man Avatar: Atk +12 (dmg d10/d10 punch); AC 17; HD 12d12; MV 30'; Act 2d20; SP sopping wet/immune to fire damage; SV Fort +8 Ref +4 Will +8; AL C.

Patron Taint: The Drownded Man

Roll Result

1 The caster is always slightly damp, as though breaking a slight sweat. The second time this result is rolled, the caster exudes enough moisture to dampen his clothes. The third time this result is rolled, the caster is always dripping, sloppy wet, with all associated drawbacks insofar as paper goods, tinderboxes, and other things that should be kept dry go.

2 The caster is always slightly damp, as though breaking a slight sweat. If both result 1 and result 2 are rolled, they don't stack; the character is just slightly damp until the second time one of these results is rolled. The second time this result is rolled, greenish algae grows in the caster's hair. The caster's skin is also somewhat slippery, creating a -1 penalty to rolls requiring a firm grip (climbing or grappling, for example). The third time this is rolled, the caster becomes so slippery that his penalty increases to -2, but he receives a +2 bonus against grappling attacks and a +2 bonus to escape from manacles, bonds, etc.

3 The caster's complexion takes on an unhealthy pale hue. The second time this result is rolled, the caster's eyes cloud over, reducing his visual acuity. Ranged attack rolls and other rolls depending on vision suffer a -2 penalty. The third time this result is rolled, the caster's complexion becomes a deathly blue, making him look entirely corpse-like.

4 The caster develops a slight cough whenever he engages in strenuous activity. The second time this result is rolled, the caster's cough is always present; he also coughs up wads of foul smelling sputum when under physical stress. The third time this result is rolled, the caster must make a DC 10 Fortitude Save whenever engaged in strenuous activity or fall into a coughing fit for 1d4 rounds.

5 Something about the caster doesn't sit well with animals. Dogs, cats, and horses will try to avoid him, and may attack if his presence is forced on them. The second time this result is rolled, the problem becomes apparent: he stinks. All Personality based rolls suffer a -2 penalty when dealing with humans or creatures with similar smell senses, unless the smell is covered with perfumes. The third time this result is rolled, perfumes aren't enough. The caster smells like rot, mud, and dead things, suffering a -1d penalty to all Personality rolls.

6 Whenever the caster casts a spell, mayfly larvae and amphipods appear in the folds of the caster's clothes and scatter across the area. The second time this result is rolled, the critters are always present, scattering when a spell is cast. Their crawling around the ticklish spots of the caster's body can be distracting, resulting in a -2 penalty to rolls requiring concentration. The third time this result is rolled, mayfly larvae, amphipods, leeches and crayfish are constantly crawling around the caster's body and falling off, leaving a fairly easily followed trail wherever he goes.

Patron Spells: The Drownded Man

1. Breathless Tranquility

2. Sunken Secrets

3. Dry Drowning

Spellburn: The Drownded Man

Roll Spellburn Result

1 A hypothermic chill comes over the caster, whether a chill of deep water or the grave. All ability damage (rather than just one point) done by this spellburn will heal the next time the caster rests, as long as he stays warm and makes a DC 15 Fortitude save.

2 Spectral leeches appear on the caster's body, draining the spellburn as stat point loss.

3 The caster must cough foul smelling water out of his lungs. He must make a DC 15 Fortitude save or spend 1d6 rounds incapacitated by the coughing; a successful save reduces this to one round. The coughing fit leaves him drained of ability points equal to the points of spellburn.

4 The Drownded Man wants company. The caster must drown an intelligent creature within the next 24 hours. If he successfully does so, the spellburn costs him no stat point losses. Failure to do so will result in the Drownded Man pulling him out of the normal flow of time for a visit; the caster will lose twice the stat points used for spellburn, drowning in the Drownded Man's realm as he sits watching, grinning, and burbling. This may happen at a very inopportune time, and the caster will be returned to the normal flow of time as soon as he left, much worse for wear.

Breathless Tranquility

Level: 1 (The Drownded Man) Range: Varies Duration: Varies Casting Time: 1 action Save: None

General: Those of the Drownded Man's realm are at peace, and beyond the cares and worries of mortals. Neither drowning nor the creatures of the water hold any terrors for them any more. This spell gives some of that peace to the living adherents of the Drownded Man for a time.

Manifestation: Roll 1d4: (1) Caster and all affected turn bluish and glassy-eyed, like drowned corpses;

(2) Caster and all affected grow gills and scales, and eyes become wide and unblinking;

(3) Caster and all affected grow heavy scales and muzzles full of fangs; (4) Area of

effect is filled with tiny fizzy bubbles

12-13	The caster can breathe underwater for 1 turn per caster level.
14-17	The caster can breathe underwater for 1 turn per caster level. In addition, during this time he is ignored by water creatures of HD 1d4 or less, including small fish, snakes, frogs, aquatic insects and swarms thereof. This includes creatures with a strong affinity for water, such as mosquitoes and dragonflies. Attacking a water creature breaks the “truce” for that creature.
18-19	The caster and up to three additional creatures can breathe underwater for 1 turn per caster level. In addition, during this time they are ignored by water creatures of HD 1d4 or less, as above.
20-23	The caster and up to three additional creatures can breathe underwater for 1 turn per caster level. In addition, during this time they are ignored by water creatures of 1 HD or less, as above.
24-27	The caster and up to six additional creatures can breathe underwater for 1 turn per caster level. In addition, during this time they are ignored by water creatures of 2 HD or less, as above.
28-29	The caster and up to six additional creatures can breathe underwater for 1 turn per caster level. In addition, during this time they are ignored by water creatures of 3 HD or less, as above.
30-31	The caster and up to ten additional creatures can breathe underwater for 1 hour per caster level. In addition, during this time they are ignored by water creatures of 5 HD or less, as above.
32+	The caster and up to ten additional creatures can breathe underwater for 1 hour per caster level. In addition, during this time they are ignored by all water creatures, as above.

Sunken Secrets

Level: 2 (The Drownded Man) Range: Varies Duration: Varies Casting Time: 1 hour Save: None

General: The Drownded Man hides secrets of many sorts under his murky waters. He is willing

to share them with certain devotees. Note that a secret could be knowledge, an item or

items, or monetary treasure, and the secret or a clue to its location must be found in or

near the water.

Manifestation: Roll 1d3: (1) A globe of will-o-wisp light leads the caster out over the water, stopping

over the area holding the secret sought for; (2) Caster turns blue and falls into a

thrashing trance for 1 or more turns, during which time he sees a vision of the secret

sought for; (3) A drowned corpse pulls itself from the water to lead the character to the

secret sought for.

14-15	The caster learns knowledge common to all the locals of the area, finds some useful herb/mineral/substance common to the area, or finds 2d6 copper coins or equivalent treasure.
16-19	The caster learns information equivalent to a true roll on a rumor table, finds some useful item uncommon (but not out of place) to the area; or finds 2d20 copper coins or equivalent treasure.
20-21	The caster learns a minor secret of a minor character (useful in some way, but not life-altering blackmail material), finds a very useful non-magic item that you wouldn't think to find in the area, or finds 2d20 silver coins or equivalent treasure.
22-25	The caster learns a major secret of a minor character (potentially life-altering blackmail material), finds a one-use magic item (potion or scroll, for instance), or finds 2d20x5 silver coins or equivalent treasure.
26-29	The caster learns a minor secret of a major character (useful in some way, but not life-altering blackmail material), finds a charge using magic item (such as a wand), or finds 2d20 gold coins or equivalent treasure.
30-31	The caster learns a major secret of a major character (potentially life-altering blackmail material), finds a permanent magic item (like a ring), or finds 2d20x10 gold coins or equivalent treasure.
32-33	The caster learns a major secret of a cosmic character (patron level of power; probably not blackmail material, but invaluable to wizardly types), finds a powerful magic item (like a sword), or finds 2d20x100 gold coins or equivalent treasure.
34+	The caster learns a major secret relating to a major plot point in the campaign or a plot hook to a major adventure, finds a legendary magic item (like the One Ring), or finds a dragon hoard level of treasure.

Dry Drowning

Level: 3 (The Drownded Man) Range: 50' + 10' per CL Duration: Varies Casting Time: 1 round Save: Will vs spell check

General: The lungs or gills of the target(s) fill with foam, at once too liquid for air-breathers and too gassy for water-breathers.

Manifestation: Roll 1d3: (1) a stream of water shoots from caster's hands hitting the target in the face

(air bubbles vs water breathers); (2) a splash of water erupts from the ground at the

target's feet (huge air bubbles vs water breathers); (3) targets turn pale and their lips turn

blue.

16-17	Coughing and gagging causes a single target to suffer a -2 penalty on attack and damage rolls, and inflicts 1d6 damage for 1d4 rounds.
18-21	Coughing and gagging causes up to three targets to suffer a -2 penalty on attack and damage rolls, and inflicts 1d6 damage for 1d4 rounds.
22-23	Coughing and gagging causes a number of targets equal to the caster's level to suffer a -2 penalty on attack and damage rolls, and inflicts 1d6 damage for 1d4+2 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for one turn.
24-26	Coughing and gagging causes a number of targets equal to (CL +1d6) to suffer a -3 penalty on attack and damage rolls, and inflicts 1d6 damage for 1d6+2 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for one turn.
27-31	Coughing and gagging causes a number of targets equal to (CL +1d12) to suffer a -3 penalty on attack and damage rolls, and inflicts 1d6 damage for 2d6 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for 1d3 turns.
32-33	Coughing and gagging causes a number of targets equal to 2x(CL +1d12) to suffer a -4 penalty on attack and damage rolls, and inflicts 1d8 damage for 2d6 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for 1d6 turns (targets of level/HD lower than CL fall unconscious with no save).
34-35	Coughing and gagging causes a number of targets equal to 3x(CL +1d12) to suffer a -4 penalty on attack and damage rolls, and inflicts 1d8 damage for 2d6+4 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for 2d4 turns (targets of level/HD lower than CL fall unconscious with no save).
36+	Coughing and gagging causes a number of targets equal to 10xCL to suffer a -5 penalty on attack and damage rolls, and inflicts 2d6 damage for 2d8+4 rounds. Additionally, affected targets must make a second saving throw or fall unconscious for 2d6 turns (targets of level/HD lower than CL fall unconscious with no save).