Food Chain Rules (v2)

These are the rules for Food Chain, a play-by-email simulation of evolution in action.

Food Chain Server Summary: runs 4 different jungles: -- one cycle every day -- one cycle every 6 hours -- novice jungle. one cycle every day -- experimental jungle. we'll test changes here.

There are all the commands that the server understands:

RULES or HELP -- sends this message
SUMMARY -- sends you just the summary of the jungle
END -- marks the end of your input -- keeps the server from thinking your .signature file is bad commands

MUTATE | Game commands.
NAME   | See below for details


Food Chain is an open-ended simulation game about evolution. Each player designs a new species of animal, and adds 50 individuals of that species to the current "jungle", where they will compete with other players' species for food, which is also other players' species. The animals under your control are both predator and prey, and your job is to strategically mutate them where possible to maximize their numbers and spread their genes. There are no registration procedures or deadlines. Simply add your custom creatures to the jungle, then sit back and watch while they fight for survival, intervening only when mutations are possible and desirable. A report on the status of the jungle may be obtained at any time.

The most successful players are the ones who own the most species - the Top 20 players are listed each report, along with the number of species they own.

The Turn Cycle

Every six hours (or at whatever frequency the GM decides), one turn is automatically processed, and the status of the jungle is updated. In that turn, each individual animal gets a chance to die of starvation, and to hunt for prey. The order in which individuals are processed is random, and an individual that gets eaten before its turn arrives misses the turn.

Getting Started

To create a new species and add it to the jungle, send mail to the Food Chain server containing a line that looks something like this -


This is an order to start a new species with the type and characteristics given. The server will record the email address which you sent the orders from, and future orders from the same address will be acknowledged as being from the same player.

Whenever you start a new species with this order, any old species currently under your control in the same game are eliminated. You could cheat here by sending in your START order using a different email account. Please don't. You may give any positive, whole-number values to the characteristics, but you may not create a species whose Body, Min and Max factors (see "Factors" below) are all the same as those of an existing species.

The types that you can give to an animal are herbivore (H) or carnivore (C). Herbivores only eat plants, while carnivores will only eat other animals.

The characteristics (also called "part-levels") that you can set are Nose(N), Eyes(Y), Ears(R), Mouth(M), Paws(P), Tail(T), Legs(L) and Brain(B). The letters in brackets are the codes to use in orders. In the example above, a new species is to be started with a Nose level of 2, a Mouth level of 2, an Eyes level of 1, and all other characteristics at level zero. Note that this does not mean that the species has no brain, but simply that it is not developed above a basic level. Fifty individuals of this species will be added to the jungle.

** Note that while you can re-start at any time, you will lose all your existing species if you do!

Monitoring Your Species

Whenever you send any mail to the Food Chain server, it sends back a report on the current status of the jungle. The report will look something like this:

Posn Species                           Player
---- -------                           ------
  1  3,12,37                 
  2  7,8,15                  
  3  23,29                             tom@yet.another.fake.address

Species                Num  Hun  Gro  Cap  Stv  Bod  Preys-On
-------                ---  ---  ---  ---  ---  ---  --------
Plant(1)               502  3.4  200  336    0    5       ---
Vole(2)               1252  3.6  237    0  330    4       5-5 [H]
Squirrel(3)             87  0.1   43    0    6    6       4-5 [H]
The first table shows the top 20 players, ranked according to the number of mutatable species they control (you can own more than one species because populations split off new species when you mutate them). Where players control the same number of mutatable (population >= 100) species, the one that controls the most individual animals is ranked higher. The "Species" column shows the ID numbers of the species under each player's control.

The second table lists every species in the jungle. The "Species" column shows the name and ID number of each species. The other columns are as follows -

Num: The total number of members of the species alive in the jungle.
Hun: The average number of turns since members successfully hunted.
Gro: The number of new members "born" last turn.
Cap: The number of members that were eaten by predators last turn.
Stv: The number of members that died of starvation last turn.
Bod: The species' Body factor (see "Factors" below).
Preys-On: The species' Min and Max factors (see below). The [H] after some species indicate that they are herbivores.

At the bottom of the report is a summary of your species' offense and defense during the cycle. This summary is difficult to read, but should make sense after you have understood all the rules.

Controlling your reports

You can ask the Food Chain server to send you regular reports automatically by sending an order that looks like this -


After this order, the server would send you a report every 4 cycles. To turn off regular reporting, specify zero(0) in the REPORT order.

You can ask for reports even if you don't currently have any species. This makes you a "spectator".


Any species that grows in number to a size of 100 individuals or more is eligible for mutation. To mutate a species you control, send an order like this to the Food Chain server -


The number ("26" in this example) is the ID number of the species that you control and wish to mutate. The "C" indicates that the new species created will be a carnivore. The other items are new values for some characteristics. Fifty individuals will be taken from the parent species and made into a new species under your control. Its characteristics will be the same as those of the parent species, with the exceptions of the ones you change.

You can change a maximum of two characteristics by any amount, but the total of all characteristics of the parent species may not differ from the characteristic total of the new species by more than two(2). As before, you may not create a species with exactly the same Body, Min and Max as an existing species.

Species Names

New species start life with the name "New Species", but you can change that as soon as you find out its ID number. Simply send an order to the Food Chain server that looks like this -

NAME 12 Sabre-Tooth Tiger

The name of the species that you control with ID 12 will be changed accordingly. Alternatively, you can name the species most recently created in the same email with the order -

NAME Fieldmouse


The characteristic values that you choose determine the values of some basic statistics called "factors". The table below shows the relationship -

       Letter    Hunt Chase Evade Power Body Min Max Res
Nose     N         1    -     -     -     1   1   1   1 
Eyes     Y         -    2     -     -     -   1   -   1 
Ears     R         -    -     1     -     1   -   1   1 
Mouth    M         -    -     -     1     1   1   2   1 
Paws     P         1    -     -     1     1   1   -   - 
Tail     T         -    2     3     -     2   1   1   1 
Legs     L         1    1     2     -     2   1   1   - 
Brain    B         -    -     -     -     -   -   2  -1
The values are cumulative so, for example, a species with Eyes of 3 and a Legs of one would have Chase factor of 7, assuming Tail was zero. These factors are used to determine who gets caught and eaten during the hunt for prey.

Important: All species start with a body factor of 3. Any body factors added from the table above are in addition to these initial 3 points.

Testing Factors

In the discussion below, reference is made to the testing of factors against each other. For example, a predator's Chase factor is tested against its prey's Evade factor to determine whether the former can catch the latter. The test will be successful for one factor or the other. If, in the example above, the test is successful for the Chase factor, then the prey will be caught. If the Evade factor is successful, the prey escapes.

When two factors (A and B) are tested, A is successful when a random number between 0 and 1 is less than (A/(A+B))^2, (where "/" denotes division and ^2 is squaring). The test for starvation, only, does not include the square.

For example, if my Chase is 2 and I am hunting a species with an Evade of 1, I have a 4/9 chance of catching it. If I have a Chase of 1 and my target has an Evade of 2, I have a 1/9 chance of catching it.

If A=B=0, then there is a 50% chance of success. If A or B is less than zero, it is set equal to zero for the purposes of this test.

Resilience And Starvation

In the factor table above, the "Res" column shows the contribution of a characteristic to the species' resilience (resistance to starvation). At its turn to hunt, an individual is first checked to see whether it has died of starvation by testing the average hunger of its population against its resilience. If the hunger is successful, then the individual dies before hunting. When the average hunger of a population is not a whole number, some proportion of the population is deemed to have a different hunger to the remainder. For example, if a population's average hunger was 2.3, then 70% of its members are deemed to be unfed for 2 turns, while the remaining 30% are deemed to be unfed for 3 turns.

For example, if the animal above had a Resistance factor of 2, then 70% of the members would have a 50% chance of starving, and the remaining 30% would have a 60% chance of starving.

The Hunt For Prey

To successfully feed, the animal must first catch its prey, then defeat it in combat. In its turn, each individual may hunt a number of times related to its hunt factor. The first 4 factors of hunt grant 1/2 an attempt each; the next 5 grant 1/3 of a hunt each; the next 10 grant 1/4 of a hunt each, and any remaining hunt factors grant 1/5 of a hunt each.

For example, an animal with a hunt factor of 3 will hunt 1.5 times. An animal with a hunt factor of 10 will hunt 3.91 times.

However, a species may only hunt if prey is available. A species may only hunt prey with a Body factor between the Min and Max of the predator. Each animal may be hunted only once, and the number of animals in a species which may be hunted is limited to 1/2 the animals in the species plus all of the net growth from the previous cycle.

For example, a species with 100 members had 50 new animals born in the previous cycle, 30 animals eaten, and 5 starved. This cycle, as many as 57 of these animals could be hunted.

Each hunt, an individual is chosen at random from the prey pool, which consists of all species (other than the predator) whose Body factor is no less than the predator's Min factor and no greater than the predator's Max factor. Plants are the only eligible prey of herbivores, but are never included in the prey pool of a carnivore. The Min and Max factors of every species in the jungle are displayed in the "Preys-On" column of each report.

To determine whether the prey can be caught, its evade factor is tested against the predator's chase factor. If the chase factor is successful, the prey is caught. To determine whether the predator can overcome its prey in combat, its power factor is tested against the prey's power factor. If the predator is successful, it eats its prey.

Whenever prey is eaten, its Body factor (minus a 5% waste factor) is added to a total for the predator's population. After all hunting is completed for the turn, each population's size grows by a number of individuals equal to this food total divided by the population's Body factor.

For example, if a species with body 20 eats 10 individuals with body 8, the body 20 species will gain 4 new members.


The species with ID=1 is special. This species has zero characteristics and factors with the exception of its body factor, which is 5. Since its hunt factor is zero, it cannot collect food so its population growth is handled differently. Each turn, 50 plant individuals is added to this population for every species in the jungle (including itself). The number of plants is limited to 9999, however, so once there are 100 or more species in the jungle, the supply of plants will stop growing.

Note: the growth rate of plants will never decrease due to a decrease in the number of species. This limitation prevents the population of the jungle from "crashing". Also note that if you make a herbivore with a Chase factor of 0, it will only have a 50% chance of successfully hunting a plant. The same goes for power. This is a frequent mistake of new players.

Hints For Newcomers

If your email address changes, you won't be able to give orders to your species any longer. In that case, write the GM,, and request an address change.

Don't expect to succeed immediately. The jungle is very much a platform for experimentation, so if your dual-carburetor, overhead camshaft mountain cat is dying off, don't be afraid to use the START order to scrap them and try something else.

Remember, though, that stability and growth are the key to success in the long run. If you can get a species to 100 population, then mutate to something better, you may be better off than starting again (at least you will have two species then, instead of one!)

When you create a new species, be sure that there is something in the jungle that it can eat. In other words, make sure that there is an abundant species whose Body factor lies between the Min and Max factors (inclusive) of your new creation.

Beware of being too successful, however. If the aforementioned mountain cat is chomping through its prey faster than they can recover, then your cats are doomed to extinction by starvation shortly after the prey have disappeared.

Use the min factor to your advantage. By excluding species with small body factors, you can ensure that your large animals won't waste their time and energy chasing small morsels.

Changes for Version 2


Food chain was originally written by Steve Andrewartha, It was subsequently fixed up quite a bit by Martin Gregory, Greg Lindahl,, is the GM of the jungles, and rewrote the mail interface to (hopefully) make it a bit more robust.

Webbed by: Greg Lindahl (