Natural Selection (2D)

This flattened companion to the 3D Natural Selection simulator keeps the same genuinely genetic mechanics on a plain 2D canvas: a population of creatures with heritable speed and camouflage-hue traits forages for food, evades predators, and reproduces with mutation once it accumulates enough energy. Speed helps a creature reach food faster but drains energy quadratically with velocity; camouflage hue determines how visible a creature is to predators relative to the current environment color. Because both traits are inherited with small random mutations at each birth, and because creatures that fail either the energy budget or predation risk simply die without reproducing, the population's trait distribution measurably drifts generation over generation toward whatever balance the current predator pressure, food supply and environment color actually reward — watch the histograms and trend line update live as that happens.