0 A.D./Open Source Release
In July 2009, the project switched from a closed development process to open source, making the code available as GPL and the art content available as CC-BY-SA, and encouraging external contributions. The team wished to attract new talent to 0 A.D., share some ideas, tools and code with the game development community, and simplify a number of issues with distribution and debugging.
Shortly afterwards, Philip (“Ykkrosh”) Taylor, a PhD student from Cambridge, made large changes to the codebase sorely requiring redesign and reimplementation, making it easier for new contributors to join.
The game has attracted many contributors in all fields of development and they have picked up the pace considerably. Shortly after the OS release, they began releasing pre-alpha and alpha versions of 0 A.D. every two to three months, each with new features, and drawing the project closer to finish step by step.