The details of norns, grendels, ettins and geats in games in the Creatures series - such as their brains, biochemistry and appearance - are to a great degree dictated by virtual genetics using a simulated genome; often called Digital DNA.
Things which are defined in genomes include:
- brain information (lobes, and the dendrites and neurons they contain)
- chemical reactions and half-lives (norns can become immortal and such things when these mutate)
- concentrations of chemicals in the bloodstream at birth
- biochemistry workings (receptors, emitters, and 'neuro emitters' which link with the brain systems)
- creature appearance; pose, pigments and gait, among other things
Each individual 'gene' of a genome can mutate in various ways and lead to interesting new behaviours which the original designers never thought of.
There are editors available which let you manipulate the genetics directly and birth new creatures with them, such as the Genetics Kit.
As of Creatures 2, creatures had around 800 genes, half of which were used for behavioural patterns and physical appearance, while the other half determined the biochemistry and the nervous system.
Did You Know? Steve Grand completely rewrote the code of Creatures when he included genetics!