"Evolution" simulates evolution of life forms.

Depending on the "Speed" parameter, every x frame the next evolutionary stage is computed and only the top n life forms stay alive. Each life form also has a life of its own and after some iteration dies. At every new stage random mutations occur, depending on the "Variation probability" parameter.

Life forms fit within their peers only if they're similar to at least some of them, this percentage is the "Fit ratio".

Each life form has seven features: three for position and size, three for color in HSL space, and one for tolerance. Tolerance means how much a life form tolerates a life form different from itself. The more a circle is transparent, the more tolerant it is.