This is a game idea from around 1999, created while finishing school, using the Quake1 engine repeatedly for the Jugend forscht contests and playing on (sometimes large) self-organized LAN parties.

Description:
The player is a scientist inside a biosphere lab and tries to create the most succesful creature in this sanbox game. He can paralyze creatures roaming the map and modify their “genes” within some limits. This includes type-selction of body-parts like hind-legs, front legs, head, torso and tail, selection of the skin texture, modification of the neural network brain, modification of stats. All settings interact and are limited to small changes.
When free, creatures roam using a standard low-level AI combined with the neural net brain, sensory simulation and physical influences. Basic actions are moving, sensing and eating. Movement and sensing costs energy, eating restores energy. Food sources are plants and other creatures. Similar creatures can mate and produce mixed offspring.
The game is intended be left running for a long time an watch what is happening.

Inspirations:
Creatures, Robofight, Quake1, AI-toolkits, venetic algorithms,Valentin Braitenberg style neural nets, Jurassic Park, …