A phenotype is a description of body type for part-based creatures (including player characters), allowing for greater diversity in character looks. Examples of phenotypes include "normal", "large", "slight", and "tall". As a side-effect of implementation, each phenotype needs its own set of animations (since different body types will move slightly differently), and some phenotypes have been developed not to change body type, but to replace one animation set with another.
Prior to version 1.69, the standard game defined only two phenotypes — "normal" and "large", and these remain the only two options at character creation. The introduction of horse riding entailed tripling the number of phenotypes, with a "riding" and "jousting" variant for each of the original phenotypes. These variants do not change a character's body type, but replace the animations so that a character appears to be riding instead of walking.