Vestigium is a worldbuilding project I've been working on for several years. The basic and essential premise is that humans used to live on what we now know as Venus and have since left, leaving artifacts behind that small creatures known as Catechumen try to understand.
The catechumen themselves are a broad category of several species of small mammals including humbunnies, mice, stoats and others who have the same physiological capacity for speech... essentially, a catechumen is any creature that can produce the same phonemes.
Vestigium as a worldbuilding project follows the history of the setting from when the first sun rises on the giant disk that is the solar system, to the changing of the world and humans arriving on Earth. The story of Vestigium, however, follows a small team of archaeologists uncovering the hidden secrets of the human species.