Architectural studies of games engines — The quake series

The move of commercial companies to "open-source" their products presents challenges for both the proposing company and the wider open source (OS) communities. The former has to align their source code to the OS practices, while the latter has to cope with large amounts of closely-developed code. This paper aims to present relevant data and results from the analysis performed on the Quake family of OSS game engines, including findings and an initial interpretation of the data. This forms the basis for the architectural understanding necessary to design and develop improvements and new features to the studied game engines. The presented approach constitutes a useful resource for games developers who wish to contribute to the further evolution of these games engines; and it provides insights into how the Quake engine architecture has evolved in practice since it was released as an open source project.