After months of collaborative research and game design, a unified game design document was finalized in the summer of 2003. The chief game designers for 0 A.D. were Bishop along with Ken “TheRealDeal” Wood, a retiree in his 60's from Arizona, and Stuart “Acumen” Walpole, a programmer in his 20's from the UK.
Development continued until 2009 as a closed-source, proprietary freeware initiative, meaning it was supposed to be offered at no charge, and it was always meant to be easily moddable, yet the source code was closed for team members only. Team membership was rather open compared to most closed-source games at the time, and to join the team all one had to do was file an application and pass an interview, though.
Throughout 2003 to 2009, the game developed at a varying pace, mostly in the art area, with a large number of units and textures designed from scratch, mostly for the Celtic and Hellenic factions. Progress on the programming side was achieved on issues like gameplay logic, random map generation, water rendering, and multiplayer networking. Two topics in the programming side served programmers as projects for undergraduate degrees in Computer Science: The water rendering by Matei Zaharia and the file ordering and caching system by Jan “janwas” Wassenberg. (Both would go on to graduate school in computer science.) Art development kept going strong under the sustained leadership of Michael D. Hafer (“Mythos_Ruler”), a contributor in his late 20's from Indiana.
Wood sadly passed away in 2006 after a long fight with cancer. Bishop stepped down as project lead in 2008 due to family obligations, with Erik “feneur” Johansson succeeding him.
Although contributions to 0 A.D. continued more or less steadily over these years, interest in TLA waned over time. As of September 2012, development of The Last Alliance has been officially discontinued. All the existing contributions to that project have been archived as study and discussion of Tolkien's works, and as inspiration for those interested in fantasy mods and games.
Over time, programmers for 0 A.D. were becoming hard to find as well, stalling development of the game. Over 2009, the team re-evaluated the development system, and looked seriously into an open source model. Finally they went for it.