Evolution Simulator

Each creature has five genes: size, speed, vision, metabolism and color. It moves toward food it can see, moves away from predators it can see, burns energy every second, and splits in two when it has stored enough. The copy's genes change a little at random. Creatures die of hunger, old age, crowding or predators. Nothing else is scripted: any change in the average traits comes only from which creatures survive long enough to split.

It is a simplified model for exploring the idea of natural selection: heritable variation plus different survival leads to changing traits. Real organisms have far more genes, sexual reproduction, development and ecology. Treat the results as a demonstration, not a prediction about real species.

Size stores more energy, is harder for predators to catch and loses less heat in the cold, but costs more upkeep. Speed reaches food and escapes sooner but costs energy to move. Vision sees food and predators from further away for a small cost. Metabolism sets the pace of life: faster movement and earlier splitting, but higher energy use and a shorter life. Color does nothing by itself; it only matters when predators are hunting.

At 5× to 10× speed the presets show a clear change within one to two minutes, after a few dozen generations. The graph in the settings panel shows the average and the spread of each trait over time.

Yes. It is free with no sign-up and no watermark, and it runs in your browser. Nothing is uploaded.

Save the world as a JSON file and load it later to continue exactly where you stopped, with every creature and the graphs. A seed number also recreates the same starting world with the same settings.

Yes. Choose 9:16, 1:1 or 16:9, a length and frame rate, and the simulator plays the world forward from the current moment into an MP4 (or WebM).

Yes. The world turns to fill a tall screen, tap a creature to inspect it, and the settings and graphs slide up from the bottom.