Lenia is a continuous cellular automaton created by Bert Wang-Chak Chan in 2018. It is a relative of Conway's Game of Life, but its cells are not just alive or dead: each one holds a value between 0 and 1, and the world changes in small steps. Many of the patterns it produces look and behave like microscopic creatures.

In every step, each cell looks at its neighborhood, a ring around it with a radius of R cells. A weighted average of the values in the ring (the kernel) is passed to the growth function: when the average is close to the growth center μ, the cell grows, and when it is further away than about the growth width σ, the cell shrinks. Each step changes the cells by only a fraction 1/T of the growth, so a larger T makes the time flow more smoothly. The world wraps around at its edges.

Each creature here lives only with its own rule parameters. Change μ or σ a little to see it adapt, change them more to see it explode or fade away, then use Restore the creature's values or Start again. You can also draw: choose Add cells or Erase cells under Draw and drag over the world with the mouse or a finger.

The creatures come from the catalog of the original Lenia project, by Bert Wang-Chak Chan, github.com/Chakazul/Lenia (MIT License). To learn more, read the paper Lenia: Biology of Artificial Life (Complex Systems, 2019).