In this paper, we describe the design and development of a social game called Familiars. Inspired by the daemons in Pullman’s “Dark Material” trilogy, Familiars are animal companions that sit on your Facebook profile and change into different animal forms based on your social activity within the social network of Facebook. Familiars takes advantage of the powerful capabilities of the developers platform of Facebook to build a multi-dimensional picture of a player’s state based on social activity, facial expression analysis on photographs and suggestions from friends. This rich information is then distilled and presented to the player in the form of animal that the familiar chooses to take. We show how the types of animals and personalities were associated in a cross-cultural user study, and present quantitative results from the social behaviours of the players within the game in addition to qualitative data gathered from questionnaire responses. Categories and Subject Descript...