In the first simulation, it starts simple. On a meadow, there are sitting some rabbits, running around and eating grass. From time to time, they reproduce. If they do not have enough to eat, they starve.

Above the two sliders at the top, the growth rate and the maximum length of the grass (in inches) can be adjusted. The longer the grass is, the more intensly green it is shown. With the next three sliders, the characteristics of the rabbits can be set, namely :
- How much grass does the rabbit need per day ?
- How much grass fits into their stomach?
- How fast do they multiply ?

The rabbit eats as much grass as fits in his stomach, yet only as much as is still there. The grass on the field becomes shorter by the same amount of "inches".

Let's make it a little more difficult for the rabbit and set out a couple of foxes into the meadow. They will eat a rabbit if by coincidence both of them get onto the same field .

With the sliders, you can set how many days the fox can keep up without eating a rabbit, as well as his reproduction rate.

For carrying it to the extreme, we add some eagles now. Their favourite food is foxes, but they don't like rabbits.

Published by A. K. Dewdney in 1984, Wator (WAter TORus) is the classic among this kind of computer simulations.

In the wide sea, there are sharks (grey) and fishes (blue) swimmmig around. The direction of their movements is determined by random. If a shark enters a field occupied by a fish, it will eat it up. Obviously, food is never a problem for the fish. Through the sliders, you can decide about the number of days until their reproduction as well as about the number of days for a shark to survive without food

If you click on the box "Sharks smell fish", the dynamics of the game will change : The sharks will no longer move randomly, but move preferentially to the neighbouring cases occupied by a fish.

This is the same thing with a little variation: There are two types of sharks, green and brown ones. In the beginnig, there is no difference between the two shark species. If you set, however, different parameters for them, the populations will evolve differently, up to the replacement of one species by the other.

Has Man exterminated the mammoth ?

And what about some other big mammals, such as the woolly rhinoceros, the cave bear, the large-horned deer, the Neanderthal Man, the aurochs, the primeval horse,...? In this game, it depends. On what? You can select it yourself:

First, there is the grass of the ice-age prairie. Depending on the climate, it can grow faster or slower.

Via the corresponding button, you can put "new mammoths" into the game. Where they feast, no grass will need some time to recover. You can determine how fast they increase and how long they survive without food.

Now you can release, via the appropriate button, some Cro Magnon hunters on the mammoths. Their success depends both on their propagation speed and their endurance against hunger. .

What did humans live on after the mammoth had vanished? They did not starve to death - like the sharks in Wator - but invented agriculture. With the help of the button "new fields", you can plant acres in the prairie. For the hunters, they are as good a source of food as a mammoth, except that these don't disappear after consumption. For a mammoth, however, a corn field is the same as a grass area - it will all graze away.