For humans, collaboration is a natural and beneficial medium with which to carry tasks, negotiate and achieve goals. In computer games, human players have worked together to achieve their objectives and many computer games today foster the need of being cooperative. Non-human entities in computer games are used predominantly as props, plot devices and adversaries. The motivation of this thesis however, is to explore and examine virtual beings engaging as equal partners with humans in collaborative computer games, resulting in richer, realistic emergent game play. To address this, the following research questions have been identified:

1. Can human and virtual beings, being heterogeneous agents, interact cooperatively in the context of computer games and what are the desirable attributes required for them to perform this collaboration as functionally equal partners?
2. What computer game framework would be required to facilitate collaboration amongst functionally equal partners?
3. How could such a collaborative computer game be designed and implemented in order to support human and virtual players engage collaboratively? To answer these questions, a number of concepts were developed to create a framework for collaborative human and virtual beings. This was then expanded upon by the design, development and implementation of a collaborative computer game called TeamMATE that supports human and virtual beings as functionally equal partners. By addressing these questions the thesis demonstrates that it is possible to design engaging computer games for entertainment, education and business where virtual beings are active participants resulting in richer computer game experiences. The TeamMATE computer game was implemented using the framework established by this work. Utilising these concepts and desirable attributes, four case studies were developed to determine whether human and virtual beings could indeed interact cooperatively in the context of computer games.