Sagan 4

Possibly the biggest exobiology project in history, Sagan 4 is the joint creation of many users. Anyone can add another species by picking a previously existing species (alive in the current generation) and “evolving” it into something new. This has led to an explosion of biodiversity on the planet. As of 2021, there were 41 kingdoms. Learn more at Sagan4.org and forum.Sagan4.org

A selection of drawings from Sagan 4 can also be seen here: disgustedorite

Or, as informed by the commenter below, here: hydromancerx