6 Billion™ - The Game Of The New Millennium

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BNBG - 6 Billion (A Brief Demographic History)
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BNBG - 6 Billion (Per Ardua Ad Astra)
BNBG - 6 Billion (Profile - David Coutts)
BNBG - 6 Billion (The Cassandra Prediction)

The Planets & The Asteroid Belt - Design Notes For 6 Billion™

Read the Design & Production of 6 Billion™ for an design overview of 6 Billion™. The article that follows has a different focus, concentrating on why and how I decided upon the upper population limits and free doubling limits for each of the 10 population tracks.

Note that when 6 Billion™ was designed the solar system had 9 planets. The solar system now comprises 8 planets and 5 dwarf planets (see Wikipedia article on the Solar System). However, although Pluto has been downgraded from planet status to dwarf planet status its use in the game is unchanged. Similarly, Ceres was previously considered an asteroid but has been promoted to dwarf planet status with no real impact on the game (it still orbits within the Asteroid Belt). In addition 2 Kuiper Belt Objects (Makemake and Haumea) and one scattered disk object (Eris, which is larger than Pluto) have been re-classified as dwarf planets. No doubt further re-classifications will occur in the future.

First, some facts, sourced mainly from the 1997 edition of Philip's Atlas Of The Universe by Patrick Moore :

Planet /
Dwarf Planet / Asteroid Belt
Mean distance
from Sun
(millions km)
(Earth =1)
Other Notes
Mercury - Roman Messenger of The Gods


57.9 4878 0.38 +427 No atmosphere.

Densest planet.

Heavily cratered

Ice at Northern pole

Venus - Roman Goddess of Love


108.2 12,104 0.90 +480 90 x Earth's
atmosphere, rich in Sulphuric Acid

No surface water

Highly volcanic



149.6 12,756 1.00 +22 Lovely

The Moon,
diameter 3,476km

Population = 6 billion

Mars - Roman God of War


227.9 6794 0.38 -23 Polar caps

Olympus Mons, highest (extinct) volcano.

2 tiny moons

The Asteroid Belt - the future home of humanity

Asteroid Belt

Various Largest 3:
(55% total mass)

(dwarf  planet)



Micro ? Orbital paths of 5,000 are known.

There may be as many as 500,000 NEA bodies over 100 meters!!!

So, how many in the main Belt?

Carbonaceous, siliceous & metal-rich.
825 quintillion tons of iron alone!

Jupiter - Roman Chief of the Gods, Ruler of Heaven.


778 143,884 2.64 -150
Gas giant.

Atmosphere 95% Hydrogen / Helium, 1000km deep.

Produces strong
radio waves.

Great Red Spot

Central core
30,000 C

Small ring system

16 moons with Io, Europa, Ganymede & Callisto all over 3,000km in diameter.

Saturn - Roman God of Agriculture.


1427 120,536 1.16 -180 Gas giant.

Atmosphere of 90%
Hydrogen / Helium.

Magnetic field
1,000 x Earth's.

Central core
15,000 C

Large ring system

18 moons with Titan by far the biggest. Tethys, Dione, Rhea & Iapetus all over 1,000km in diameter.

Uranus - Greek God of the Sky


2870 51,118 1.17 -214 Ice giant.

Liquid water / water-ice ocean. Atmosphere of Ammonia & Methane, with Hydrogen / Helium above that.

No internal heat.

Small ring system

Axial tilt at 90%

15 moons with Ariel, Umbriel, Titania & Oberon all over 1,000km in diameter.

Neptune - Roman God of the Sea.


4497 50,538 1.20 -220 Ice giant.

Planetary ices, such as water-ice. Atmosphere of Hydrogen / Helium / Methane. White clouds, very windy.

Strong internal heat.

Tiny ring system

8 moons, with Triton (2,705km diameter) much the largest.

Numerous Kuiper Belt Objects identified between Neptune & Pluto.

Pluto - Greek God of The Underworld


5900 2324 0.06 -230 Dwarf planet.

Eccentric orbit,
inclined 17 degrees.

1 large moon, Charon,  with diameter of 1,270km, only 20,000km from Pluto.

Bear in mind that 6 Billion™ uses the exponential series 1, 2, 4, 8 etc to reflect population doubling, and I'd decided that no planet was going to be excluded from having a population. Hence, all population tracks use numbers in this series. And here are the figures from 6 Billion™ :

Planet /
Dwarf Planet / Asteroid Belt
Upper Limit
Free Doubling
Limit (billions)
Notes - why live there?

6 Billion™ assumes space habitats and surface dome habitats become a reality, with all the required technologies to make that happen.

Mercury 8 1 Orbiting space habitats unlikely - too close to Sun. Just ask Icarus...

Surface domes unlikely - too close to Sun. A tan in 5 seconds...

Underground mining colony only? Penal colony? Tax Haven? Base for Solar Energy collection.

Most likely site for anti-matter production thanks to abundant sunlight and vacuum.

A tough place to live, even in space... hence the X2 qualifier in the holding box   and the low free doubling limit.

Venus 128 16 Popular for orbiting habitats, good Solar energy.

Long-term terraforming might allow surface colony and restoration of oceans...

Close to the Earth, always an advantage...

Earth 1024 128 Most likely location for orbiting space habitats, good Solar energy. The Moon is large, and suitable for surface domes and mining activity.

If we could live in space, many would choose a view of Earth...

Mars 256 32
After Earth (including the Moon), the next most likely surface colony. Polar caps provide water. Very popular choice for terraforming ideas.

A good candidate for a Space Elevator.

Orbiting space habitats and Phobos & Deimos.

Close to the Earth, always an advantage..

Asteroid Belt 1024 No limit
Staggering abundance of resources (hence no free doubling limit), including ice, rock and metals. Micro gravity an advantage to mining / trade activities. Still close enough to Sun for useable Solar energy.

Countless hollowed-out asteroids as space habitats, hence the high upper limit.

Includes Ceres, now re-classified as a dwarf planet.

Jupiter 128 16 Surface colonies on several satellites and Trojan asteroids.

Space habitats.

Highly varied moons, large beautiful planet.

Downside - a long way from Earth...

Saturn 128 16 Surface colonies on several satellites; Titan even has a thick atmosphere.

Stunning ring system.

Space habitats.

Downside - a long way from Earth...

Uranus 64 8 Surface colonies on several satellites.

Space habitats for Helium-3 atmosphere mining. 

Downside - even further away from Earth...

Neptune 64 8 Surface colonies on several satellites.

Space habitats for Helium-3 atmosphere mining.

Many Kuiper Belt Objects (KBOs) including Trans-Neptunian Objects (TNOs) "factored into" Neptune. The moon Triton is believed to be a captured KBO.

Downside - even further away from Earth...

Pluto /
32 4 Surface colony on Pluto, plus surface colony on Charon. 

Plenty of useful ice. Collection of solar energy much more difficult (but still not impossible).

Staging post before leaving Solar System. Outpost for Oort Cloud mining operations. Tax-haven? Penal Colony? Otherwise, who'd want to live there? Hence the X2 qualifier in the holding box. That, and the harsh conditions so far from the Sun and Earth.

Pluto is the largest body in the Kuiper Belt, but was recently downgraded from planet status to dwarf planet status. Refer Wikipedia - Definition of a planet

Pluto / Charon are already represented in 6 Billion™. Ceres is easily reflected in the vastness of the population track for the Asteroid Belt. The easiest way to accommodate the additional dwarf planets (Haumea, Makemake and Eris) in games terms is to ignore them, and simply assume that they are generically reflected in the Neptune and Pluto population tracks.

Dwarf Planets (except Pluto):

However, if players wish to create their own population tracks for our newly classified dwarf planets then try the following suggestions:

Dwarf Planet Population
Upper Limit
Free Doubling
Limit (billions)
Additional rules and notes


Ceres 32 4 Use 4-2-1 victory point rules

Same distance as Asteroid Belt

See Wikipedia article - Ceres

Haumea 8 1 Use 4-2-1 victory point rules

Distance 3 from Pluto

X2 colonisation rules apply

Kuiper Belt Object

See Wikipedia article - Haumea

Makemake 8 1 Use 4-2-1 victory point rules

Distance 3 from Pluto

X2 colonisation rules apply

Kuiper Belt Object

See Wikipedia article - Makemake

Eris 16 2 Use 4-2-1 victory point rules

Distance 6 from Pluto

X2 colonisation rules apply

Bigger than Pluto, but much more remote.

Scattered disc object.

See Wikipedia article - Eris

There are no Discovery Cards for these dwarf planets, so victory points cannot be doubled. Colonisation of these population tracks is not required to trigger game end. In other words, the end game is still triggered if all 10 original population tracks are colonised (or a token reaches a 1,024 space).

Kuiper Belt Objects

The Kuiper Belt includes many icy objects in addition to the dwarf planets classified so far. A Kuiper Belt variant for 6 Billion™ is available. See Wikipedia article on Kuiper Belt.

Further reading:

The Planets (based on the BBC series) - David McNab and James Younger
The Snows Of Mons Olympus - Arthur C. Clarke
Visions Of Space - David A. Hardy
The Case For Mars - Robert Zubrin
Islands In The Sky (Bold New Ideas for Colonising Space) - Edited by Stanley Schmidt and Robert Zubrin
The Millennial Project (Colonising The Galaxy In Eight Easy Steps) - Marshall T. Savage
Mining The Sky (Untold Riches from the Asteroids, Comets and Planets) - John S. Lewis
Pale Blue Dot (A Vision Of The Human Future In Space) - Carl Sagan
The Giant Leap (Mankind Heads For The Stars) - Adrian Berry
The High Frontier (Human Colonies In Space) - Gerard K. O'Neill
Our Cosmic Future (Humanity's fate in the Universe) - Nikos Prantzos
The Road To The Stars - Iain Nicolson
Journey To The Stars (Space Exploration - Tomorrow And Beyond) - Robert Jastrow
The Universe In Space And Time - Prof. Van Den Bergh
In The Centre Of Immensities - Bernard Lovell

Meet The Planets - Time Magazine 31st October, 2005 - article by Michael D. Lemonick

The Singularity by Vernor Vinge

Konstanin Tsiolkovsky, who said "Humanity will not remain on the Earth forever, but in the pursuit of light and space will at first timidly penetrate beyond the limits of the atmosphere, and then will conquer all the space around the Sun." (August 12,1911)

The World, the Flesh & the Devil (An Enquiry into the Future of the Three Enemies of the Rational Soul) by J D Bernal (written in 1929)

Wikipedia  - article on Kuiper Belt

Wikipedia - Definition of a planet

For an idea of travel times within the Solar System, read this Crude Guide To Travel Times in The Solar System. For a list of articles by me, see the Articles page.

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Copyright © 1999 Board Not Bored Games Pty Ltd.
Last modified: August 07, 1999