I was worried when I got an e-mail from David telling me that he had designed a game based on the fact that the human population is growing at an exponential rate, with the doubling time already worryingly short. As a theme, this seemed straight out of Greg Aleknevicus's article on topics that are better left untouched in a game context. Fortunately, while that may have been the initial inspiration, the reality as it has emerged in the game has no connection with realities of the scientific sort. Here the premises are

• The Earth can support a population over 100 times its present size. This growth can be achieved without any worries about land degradation, conflict over resources, and so on.
• All the other planets in the solar system are suitable for human habitation and every bit as bountiful and elastic-sided as this imaginary Earth.
• Some planets are further away than others.

But you don't need good believable science, or even good believable anything, to provide a framework for an interesting game. All a game needs are rules that fit nicely together to produce an entertaining and competitive situation and David's bits of science fantasy do that. When playing, you just have to imagine that you are in the scientific world of Jules Verne, H.G. Wells, or even Kansas.

In essence, 6 Billion is a game about competing for position in a set of rankings. There are ten population tracks: one for each of the nine planets in the solar system and one for the asteroid belt. Markers representing the population of each player and non-player faction move forwards, and sometimes backwards, along these tracks. When the game ends, points are awarded to the first three markers on each track. The winner is the player with the highest total.

At the start of the game, the player factions, together with one or two neutrals, will each have one population marker on the board and it will be sitting on the 'one billion' mark on Earth. From this base each faction will seek to increase its numbers both on Earth and by colonizing the other planets. Population increases occur automatically as long as the total population on the planet is not too large; thereafter it is down to card play. And it is card play that is at the heart of the system, giving players opportunities to increase their populations, to travel to other planets and to irritate their opponents.

At the start of the game, each player has a hand of six cards, one of which will be a "hidden agenda". This nominates either Earth, Mars or the Asteroid Belt as the player's planet of special interest. Come game-end any victory points they score here will be doubled. It is a neat little device to break up the symmetry and to introduce an element of uncertainty into any calculations you may be making about who is doing how well. On your turn you play one or two of these cards and then make your hand back up to six by drawing either from the face-down deck or from the pool of three face-up cards displayed by the side of the board.

Basic cards are 'double', 'new colony' and 'migrants' and each comes in three flavours: those you play on yourself, those you play on an opponent and those you play on a neutral. A 'double' card enables you to nominate a token and move it one space further along its track, thereby doubling that faction's population on that planet. The point of doing this to one of your own tokens is clear. Doing it to someone else's sounds, at first, to be needlessly altruistic, but it's not. In the first place you get victory points for doing it and in the second, while you may be helping faction B, you can often arrange it so that this will be at the expense of faction C, who seems to you to be doing too well. For example, C might currently be in first place on Mars, with B one space behind. By moving B up level with him, you are boosting B's potential score but reducing C's.

The 'new colony' and 'migrants' cards are similar, differing only in that 'migrants' can only go to a planet which is already inhabited, and again they come in the three flavours--you, an opponent or a neutral--with victory points on offer in the latter two cases. What happens here is that part of the population on one planet heads off to a new one, with the card telling you how far they can travel to reach their new home. If the faction's population on the planet they are leaving is large, this will have no effect on the position of the factions's token; if it isn't, the local population loss will be discernable and the token moves back one. So here again there is scope for malice. You and I might be in joint first place on Saturn, neither of us being too far along the track. I play a new colony card, move your Saturn token back one and send the people concerned off to some planet I don't care about. I am now in sole first place on Saturn. Plus, I have collected three victory points for doing you a favour. Very satisfying.

In addition to these core cards, there is a whole raft of others taking us into "take that, you fiend" territory. For example, I play a double card on myself for a planet where you have an interest; you don't want my token moving forward on this track and play a 'famine' card, cancelling my double; I then play a 'power politics' card, which cancels your famine and restores my double. Another card in this section enables you to double your victory points from a specified non 'hidden agenda' planet. There is also one that you can use to stop a faction that is trying to establish itself on a planet from doing so. And so on.

The game ends when either all the planets are inhabited or when someone's marker reaches the end of the track on either Earth or the Asteroid Belt.

A set of optional rules brings in three extra, non-planetary tracks where players can also jostle for position and score victory points. These don't complicate or lengthen the game unduly but do have the good effect of providing each card with an alternative use, thereby increasing your tactical options. They also provide a means whereby players can manipulate the (at times very important) turn order.

6 Billion is a very well crafted game. The mechanics flow logically from the premises of the theme and they work smoothly, giving the impression of a game that has been carefully polished and thought about over a long period. It also strikes a good balance between constructive play, aimed at improving your own position, and destructive, intended to thwart your opponents. Added to that it has a fair number of original ideas and decent components--especially when you take into account the very competitive price and the fact that it has been published by a small company. I also enjoyed playing it and will happily play it again should someone else suggest it. That said, it is not going to be a game that I am likely to push forward when the choice of what to play lies with me. This is not for any objective reasons, but because of the theme, which, as you will have gathered from my opening remarks, is not one I am in sympathy with. As a topic for a game, the human race's ability to outbreed the hamster was never going to catch my imagination in the way that trains, elections or horse racing can. However, that is a purely personal reaction and the fact that I go round wearing a "Malthus was right" t-shirt is no reason why you should do the same.

I was worried when I got an e-mail from David telling me that he had designed a game based on the fact that the human population is growing at an exponential rate, with the doubling time already worryingly short. As a theme, this seemed straight out of Greg Aleknevicus's article on topics that are better left untouched in a game context. Fortunately, while that may have been the initial inspiration, the reality as it has emerged in the game has no connection with realities of the scientific sort. Here the premises are

• The Earth can support a population over 100 times its present size. This growth can be achieved without any worries about land degradation, conflict over resources, and so on.
• All the other planets in the solar system are suitable for human habitation and every bit as bountiful and elastic-sided as this imaginary Earth.
• Some planets are further away than others.

But you don't need good believable science, or even good believable anything, to provide a framework for an interesting game. All a game needs are rules that fit nicely together to produce an entertaining and competitive situation and David's bits of science fantasy do that. When playing, you just have to imagine that you are in the scientific world of Jules Verne, H.G. Wells, or even Kansas.

In essence, 6 Billion is a game about competing for position in a set of rankings. There are ten population tracks: one for each of the nine planets in the solar system and one for the asteroid belt. Markers representing the population of each player and non-player faction move forwards, and sometimes backwards, along these tracks. When the game ends, points are awarded to the first three markers on each track. The winner is the player with the highest total.

At the start of the game, the player factions, together with one or two neutrals, will each have one population marker on the board and it will be sitting on the 'one billion' mark on Earth. From this base each faction will seek to increase its numbers both on Earth and by colonizing the other planets. Population increases occur automatically as long as the total population on the planet is not too large; thereafter it is down to card play. And it is card play that is at the heart of the system, giving players opportunities to increase their populations, to travel to other planets and to irritate their opponents.

At the start of the game, each player has a hand of six cards, one of which will be a "hidden agenda". This nominates either Earth, Mars or the Asteroid Belt as the player's planet of special interest. Come game-end any victory points they score here will be doubled. It is a neat little device to break up the symmetry and to introduce an element of uncertainty into any calculations you may be making about who is doing how well. On your turn you play one or two of these cards and then make your hand back up to six by drawing either from the face-down deck or from the pool of three face-up cards displayed by the side of the board.

Basic cards are 'double', 'new colony' and 'migrants' and each comes in three flavours: those you play on yourself, those you play on an opponent and those you play on a neutral. A 'double' card enables you to nominate a token and move it one space further along its track, thereby doubling that faction's population on that planet. The point of doing this to one of your own tokens is clear. Doing it to someone else's sounds, at first, to be needlessly altruistic, but it's not. In the first place you get victory points for doing it and in the second, while you may be helping faction B, you can often arrange it so that this will be at the expense of faction C, who seems to you to be doing too well. For example, C might currently be in first place on Mars, with B one space behind. By moving B up level with him, you are boosting B's potential score but reducing C's.

The 'new colony' and 'migrants' cards are similar, differing only in that 'migrants' can only go to a planet which is already inhabited, and again they come in the three flavours--you, an opponent or a neutral--with victory points on offer in the latter two cases. What happens here is that part of the population on one planet heads off to a new one, with the card telling you how far they can travel to reach their new home. If the faction's population on the planet they are leaving is large, this will have no effect on the position of the factions's token; if it isn't, the local population loss will be discernable and the token moves back one. So here again there is scope for malice. You and I might be in joint first place on Saturn, neither of us being too far along the track. I play a new colony card, move your Saturn token back one and send the people concerned off to some planet I don't care about. I am now in sole first place on Saturn. Plus, I have collected three victory points for doing you a favour. Very satisfying.

In addition to these core cards, there is a whole raft of others taking us into "take that, you fiend" territory. For example, I play a double card on myself for a planet where you have an interest; you don't want my token moving forward on this track and play a 'famine' card, cancelling my double; I then play a 'power politics' card, which cancels your famine and restores my double. Another card in this section enables you to double your victory points from a specified non 'hidden agenda' planet. There is also one that you can use to stop a faction that is trying to establish itself on a planet from doing so. And so on.

The game ends when either all the planets are inhabited or when someone's marker reaches the end of the track on either Earth or the Asteroid Belt.

A set of optional rules brings in three extra, non-planetary tracks where players can also jostle for position and score victory points. These don't complicate or lengthen the game unduly but do have the good effect of providing each card with an alternative use, thereby increasing your tactical options. They also provide a means whereby players can manipulate the (at times very important) turn order.

6 Billion is a very well crafted game. The mechanics flow logically from the premises of the theme and they work smoothly, giving the impression of a game that has been carefully polished and thought about over a long period. It also strikes a good balance between constructive play, aimed at improving your own position, and destructive, intended to thwart your opponents. Added to that it has a fair number of original ideas and decent components--especially when you take into account the very competitive price and the fact that it has been published by a small company. I also enjoyed playing it and will happily play it again should someone else suggest it. That said, it is not going to be a game that I am likely to push forward when the choice of what to play lies with me. This is not for any objective reasons, but because of the theme, which, as you will have gathered from my opening remarks, is not one I am in sympathy with. As a topic for a game, the human race's ability to outbreed the hamster was never going to catch my imagination in the way that trains, elections or horse racing can. However, that is a purely personal reaction and the fact that I go round wearing a "Malthus was right" t-shirt is no reason why you should do the same.

Earth's population is growing at an exponential rate. How to make room for all the people? Let's colonize the solar system! Everyone starts as a faction on Earth; there are also one or two neutral factions. Players use their cards to advance along the population tracks of the planets and Asteroid Belt, colonize and migrate to them, and thwart rivals who are attempting to do the same. Those who have the first, second, and third most populous colonies score points. Helping the neutral faction scores a few altruism points and is a fine tactic for confounding opponents. The game ends when someone reaches the end of the Earth's or Asteroid Belt's population track, or when all planets plus the Asteroid Belt are colonized. The play may seem sedate at first, but culminates in a mad scramble for position that makes outer space seem more like the Wild West than the Final Frontier.

This is the best game I've played in the past year. I play with 2 other players so we have to play a 3-player game. Many games for 2-6 players don't work well with just 2 or 3 players. 6 Billion works fine for 3 players and is an excellent 2-player game. Many games we play get tedious especially near the end when there may not be much left to do. In 6 Billion, each action is extremely important and these actions become crucial as you approach the end of the game. In fact 6 Billion is a game which may end too abruptly. The only player happy to see the game end is the one with the most victory points. But you don't really know who wins until you add up the victory points.

My first game was a 3-player game with just the basic rules. This first game went very smoothly which is unusual. The card play is very important, but was not difficult, even in our first game, because of the information printed on the cards. You can do at most 2 actions where an action means playing an action card. Some of these actions are really neat. For example you can play a card which helps an opponent! You get 3 victory points for helping an opponent. Now what you have to do is try to help an opponent in such a way that it doesn't have a negative affect on you. Another neat thing is that there are 1 or 2 neutral players usually controlled by the person who is behind. If you control a neutral player, you control who gets migrated and where.

My second game was a 2 player game with the advanced rules. This was a very enjoyable game. I would recommend using the advanced rules because you have more options and the game is not any more complicated once you understand how to use the 3 additional tracks. The best thing about the advanced rules is that many cards can be used in 2 completely different ways.

The components are quite good. To be more precise, they are excellent where they need to be excellent, like the large deck of cards, and are cheap where it doesn't matter, like the colored chips. The cards are the most important and most difficult part of the game. What is really nice is that there is helpful information on the cards. This makes the game much easier to understand and play. I don't know why this isn't done more often. For example, a card can be an action, cancel, or response card. You don't have to memorize what each card is (action, response, or cancel) because each card has a letter on it, either an 'a', 'c', or 'r'. If a card has some unusual feature, like it's removed from the game after played, this is stated on the card.

Despite the fact that there are at least 10 tracks, the game is in no way tedious. All you have to do each turn is move 3 or 4 tokens from one space to another. The only arithmetic you have to do is add a few fractions like 1/2 +1/2, or 1/2 +1/4 +1/4. You have to check if fractions add up to 1. If you don't like doing this then use 50% for 1/2 and 25% for 1/4.

The board could be a little larger, but it works fine. The only problem is the holding boxes are too small. But the population and victory point tracks are fine. There is an optional board pictured on the 6 Billion Web page. You can make up a large version of this board yourself. It's a more functional board (but not as pretty) because all the population tracks go in a straight line and have percentages 25%, 50% and 100% printed on the appropriate spaces. At the end of each track are large holding squares for migrants and colonists.

This game is a great buy. In addition there is a 6 Billion web site which has scenarios, an expanded and updated version of the rules, examples of play, and many other things. I could spend hours going through the fascinating material on this web page.

I highly recommend this game.

This game has been out for a few years, but I've only just discovered it. Hard to get in the USA.

The game is about the colonization of the solar system, and seems to work well with 2, 4 or 5. 3 players if ok if you dump one of the neutral factions and just play with 1 neutral.

I love it as it's easy to learn, and even my girl friend will play it!

I think that is a very well balanced game with interesting options. It is not boring and quite quick. The players with the lowest score are never out of the game, because they can grow quicker than the others.

Some cards are useless at the beginning of the game but are essential going on.

Un sideback: the population chart printed on the board sometimes is not very clear (due to the colors of the board under the numbers of the chart).