Ecosystem

Grass regrows, herbivores graze and flock, predators hunt. Speed, vision and size are inherited with mutation, so selection happens in front of you.

Sim speed

Presets

Brush size Colour agents by

Grass regrowth Herbivore reproduction cost Predator reproduction cost Mutation rate Initial herbivores Initial predators

Initial counts apply on Reset.

Use the Inspect tool and click an animal.

How it works

Herbivores flee predators, seek the best grass in view, and flock (separation, alignment, cohesion). Herds also dilute attacks.
Predators chase the nearest prey but tire: stamina drains while sprinting, so fast prey escape.
Faster, sharper-sighted or bigger bodies cost more energy every second. Selection balances these costs against survival.
Offspring inherit parent traits multiplied by a random mutation. Watch the trait histograms and mean trend lines drift.
The phase plane draws the Lotka–Volterra cycle: herbivores on x, predators on y, spiralling or orbiting.

Spatial hashing keeps neighbour queries cheap, so a thousand agents run at full frame rate. Grass regrows on a fertility map; water blocks movement.